WILLIAM Q. HULL Associate Editor in eollnboration with
HARVEY KEEL
AND
JOHN KENNEY, JR.
BERNARD W. GAMSON
Dicalite D i d i o n , Great h k e s Carbon Corp., Los Angel-, Cdif.
D
IATOMACEOUS earth is being used in an ever-increasing number of chemical proceming and other industries. This versatile material is keyed to virtually all facets of the modern industrial economy. The major u e s in filter aids, insulation, and fillers have grown to over 200 and range from the prodnotion of edible products, such aa sugar, to the refining of petroleum. U. 8. production during the laat decade has doubled and this year ia expected ta exceed 300,ooOtons (Table I). Diatomaceas, sometimes known aa Bacillerieae, are the micrcscopic plants related to the algae whose remains make up d i a t e maceow 4. Theae diatoms have existed for geologic ages and are still abundant in both salt and fresh watei where they serve aa fmd for living organism and, after decomposition, for other plants. Fossils of dead diatoms, a8 well as living diatom, are too small to he Been individually without high magnification. In a living maaa they are easily visible aa the brown gmwth on the surface of stegnant water, mud, rocka, and seaweed and other
Great h k e s Carbon Corp., Morton Gmw, 111.
wet surfaces where light and water have been present long enough for the growth to accumulate. The diatoms are singlecelled planta conaisting of two parts which fit together in the same manner aa the two halves of a pillbox. The frustules are fashioned in countleas shapes, rather eimilar to the complex beauty of snowhkes. There are some 10,ooO varieties of diatoms of which Wolle, as early aa 1894, had sketched over 2300 that had been identilied in North America (9). Reprodnotion is frequently by mbdiviaion, and the rate of propagation may be extremely rapid, one frustule becoming a billion diatom in a under favorable conditions. . Derid In many ~ r e over a ~ the world, in regions which at one time or another were under water, are found large deposits formed during the Miocene and Pleistocene ages aa diatoms died and settled to oeean or lake bottoms. Many countries had diatomaceousearth industries a6 early 88 1922 (4). In the United S t a h , the largest and purest deposits are located in the Weat although at
256
one time deposits in Connecticut, Maryland, New Hampshire, New York, and Virginia were commercially operated. Deposits of great size and high purity are located in California in the Lompoc area approximately 50 miles northwest of Santa Barbara. These deposits have been exploited since 1893. All present-day plants of commercial significance are located in the western states. While there are several other processors, there are two major producers of diatomaceous earth products, namely, Great Lakes Carbon Corp., and. Johns-Manville Go., the latter having operated a plant a t Lompoc since it purchased the existing plant a t that site in the latter part of 1928. Great Lakes Carbon Corp.'s plants at Lompoc and other locations are described here.
TABLE I. DIATOMACEOUS EARTH SALES" Industry Sales, Tons Year 95,500b 1929 95,000 1930 85,000 1931 71,000 1932 73,000 1933 82,000 1934 89 ,000 1935 95 ,000 1936 98 000 1937 88 :000 1938 102,000 1939 111,000 1940 148,000 1941 167,000 1942 179,000 1943 179 ,000 1944 190,000 1945 221,000 1946 227 ,000 1947 237,000 1948 231,000 1949 254 000 1960 292:OOO (estimated) 1951 a Calculated from data presented t o U. S. Bureau of Mines. b Average for years of 1927,1928. and 1929.
x
In its natural form, diatomaceous earth is an amorphous mineral consisting chiefly of silica (Table 11). All deposits contain physically absorbed water, ranging in content from 20 to SO'%. The density of the naturally occurring formation is approximately 25 t o 45 pounds per cubic foot. Partial air drying and bulking of the material during mining reduces the density to about 20 to 30 pounds per cubic foot. Processing reduces the apparent dry density to approximately 8 to 12 pounds per cubic foot in powdered condition. The material's unique structure and chemical inertness essentially account for the many applications of diatomaceous earth.
TABLE 11. TYPICAL CHEMICAL AXALYSIS O F DICALITE PRODTCTS (DRY BASIS) Iiatural,
72
Si02
AlzOs Fez03 CaO MgO Ignition loss Cndetermined
251
INDUSTRIAL AND ENGINEERING CHEMISTRY
February 1953
86.8 4.1 1.6 1.7 0.4 4.6 0.8
Calcined,
White,
91.0 4.6 1.9 1.4 0.4 0.3 0.4
87.9 5.9 1.1
%
%
1.1
0.3 0.1 3.6
Diatomaceous Earth .Materials Are Used for Filter Aids, Fillers, and Thermal Insulation One of the earliest recorded uses of diatomaceous earth was in construction. The architects of the Cathedral of St. Sophia in Constantinople, around 532 A.D., lightened the construction of a 107-foot dome through the use of brick made from diatomaceous earth ( 3 ) . Inasmuch as such brick has very low strength, its use for simple structural purposes has not survived. Alfred
Nobel used diatomaceous earth as a n absorbant for liquid nitroglycerin t o make dynamite, but this use has become minor. It was considered as the base for a bromine-containing disinfectant and, in the form of asphalt-dipped, waterproof blocks, for cold storage insulation. Many other temporary uses have been discarded in the interest of newer and more practical developments. Major, present-day uses of diatomaceous earth are as filter aids, fillers, and for thermal insulation (Table 111). The first big scale application, described as early as 1899, was in the filtering of raw cane sugar solutions. This use is important today and has made possible increased production of high quality sugar ( 1 , 6 , 8 ,14, 19, a i ) . Successful use in cane sugar production led to utilization of diatomaceous earth in beet sugar refineries and many other industries. It has largely replaced paper pulp, compressed cotton, and asbestos-cellulose pads formerly used in brewing and winemaking to produce a brilliantly clear product (17, 18, 66). I n modern breweries, diatomaceous earth filter aids are used for filtering the wort and fermented beer as well as for final polish ( 7 , 60). I t s use as both filter aid and filler :n the production of paints, lacquers, and varnishes has been described ( 1 1 ) . It is commonly used as a filler in newsprint, boxboard, and other paper products. It finds a major outlet as a filter aid in controlling stream pollution and conserving water by the treatment of paper mill waters and other industrial effluents (IO, 16, IS). More recent uses include treatment of municipal water supplies, mobile military water purification units, and the production of penicillin and streptomycin. Insulation products made from diatomaceous earth include cut and formed bricks, molded blocks, pipe coverings, loose-fill products, and concrete aggregates. I t s stability at high temperatures has resulted in diatomaceous earth becoming one of the most widely used high temperature insulation materials.
TABLE111.
PROBABLE
END USE
OF PRODUCTS
E n d Use Filtration Fillers Insulation Others
DIATOMACEOUS EARTH Use, 70
70 20 5 5
The processing of crude diatomaceous earth into filter aids can be briefly summarized. Natural grades are made by drying the crushed ore, milling, and air-separating the dispersed particles into definite particle-size fractions. Calcined products are given the same preliminary processing, but the calcination at high temperatures results in a change in the surface of the diatom and a n increase in the particle size due to agglomeration. White or process calcined products are fluxed with soda ash or other fluxing material for increased effect on particle size and surface characteristics (Table IV). Diatomaceous Earth Is a n Ideal Adjunct to Industrial Filtration Filtration is a universally used operation in the chemical industries. It is interesting, therefore, that its basic principles are not always considered and that, as a chemical process, it has not developed along engineering lines to a degree comparable with other chemical engineering unit operations. Essentially, filtration is a straining operation. The main object in industrial filtration is to separate solids from liquids. Practically, a compromise is reached between speed of separation and its efficiency. I n the process industries, several types of equipment are used, and there are many modifications of the individual types. Basi-
258
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 45, No. 2
the solid matter is removed. This, in effect, opens up a fresh diatomaceous earth surface on each revolution of the filter drum permitting large volume throughput on a uniform quality control basis. Filters operating on this principle are capable of handling as much as several thousand gallons of liquor. per hour. Dicalite Division of Great Lakes Carbon Corp. Processes Diatomaceous Earth in a Modern Outdoor Plant at Lompoc, Calif. Originally a partnership established in May 1919, Great Lakes Carbon Corp. wa.s incorporated in April 1923. Until 1932 the company was engaged principally in the distribution of coal at a wholesale level and in acting as sales agent for a number of important producers of coal. Diversification began Soda -4sh Is Added as Fluxing Agent to Some Diatomaceous Earth Products in the late twenties when the comSoda ash storage tank at right and underneath i t , the soda ash pulverizer pany became interested in petroleum coke. One after another, new products became available under the GLC cally, however, filters can be classified as gravitj filters, piesiure brand until today there are six divisions of the company with filters, and vacuum filters. products as indicated: The speed and efficiency of filtration can be affected by (1) frequent cleaning of filtering surface; (2) variation in pressure Carbon Division Petroleum coke and calcined petroleum used to force the liquid through the filtering surface and its coatcoke Electrode Division Graphite and amorphous carbon elecing of solids; (3) increasing the filtering surface area, (4)use of trodes; graphite anodes, graphit,e filter aids; and (5) temperature which affects the viscosity of the molds, graphite casting beds, and carliquid being filtered. bon and graphite specialties The properties of diatomaceous earth make it a n ideal filter aid, Oil. and Gas DiviCrude petroleum and natural gas sion and the use of filter aids made from this material has perhaps been Dicalite Division Diatomaceous silica for filter aids, fillers, the primary factor in making industrial filtration possible In and insulating uses milling, the individual diatoms are separated from each other, Perlite Division Perlibe ore and expanded perlite products but, each tiny fossil retains its original shape. I n use, the irreguMissouri Coke and Premium foundry and industry coke; lar but rigid shapes form a bulky filter cake or precoat which Chemical Divicoke coproducts including coal t,ar, consists of lOy0solids and 90% voids. I n many cases, the opension ammonium sulfate, nitrat,ion and inings between the individual diatoms through which the liquor dustrial pure grades of benzene, toluene, xylene, and crude light and must pass are so small that even bacteria are strained from an heavy solvent impure liquid. I n most industrial filtrations, diatomaceous silica filter aid Great Lakes Carbon entered the diatomaceous earth products is added to the unfiltered liquor Filtration removes both the industry in 1944 when i t acquired The Dicalite Co., a h-evada filter aid added and the foreign solids present in the liquor. The filter cake formed is porous, rigid, and substantially incomprescorporation, with diatomaceous earth operations at Kalteria and Lompoc, Calif., and Terrebonne, Ore. Later, additional crud(, sible. Because of the bulky nature of diatomaceous silica, the reserves a t Basalt, Nev., mere acquired. Today plants are operamount used is only about 0.5yoof the weight of the liquor being filtered, although the actual amount used varies considerably ated at Lompoc, Walteria, Basalt, and Terrebonne. The plant a t Terrebonne is the only major one in existence that produces between different applications. Consideration must also be given to the form and manner in filter aids from remains of fresh-water diatoms. The company rapidly became one of the two major U. S. producers of diatowhich the filter aid is added. A batch addition, either dry or as a slurry, is satisfactory for batch processes and dry addition is maceous earth products. The Dicalite plant a t Lompoc, Calif., is the latest addition to more common. Slurry addition by proportioning equipment is Great Lakes Carbon’s operating units and is the most modern common in continuous operations. Adequate mixing must be provided in all cases. diatomaceous earth processing plant in the United States. The One of the unique properties of diatomaceous earth filter aids process design and specifications were prepared b y Great Lakes is the ability to form a cohesive precoat of filter cake on a conCarbon Corp. I n early 1951, KaiPer Engineers, Division of Henry tinuous rotary filter. It is this property which, more than anyJ. Kaiser Co., was retained t o engineer and construct the plant. thing else, has permitted the development of rotary vacuum Initial construction began in June 1951, and the first commercial filters, capable of handling quantities of liquor which would be product was shipped from the plant in April 1952. The plant impossible in a n y other type of filter on an economical scale. is of the outdoor type with only bagging, warehousing, and I n a typical precoat operation, the clean drum is precoated b y centralized control in enclosed buildings. Outstanding features means of a slurry of filter aid to a thickness of 1 to 2 inches uniinclude an automatic centralized control system, highly mechaformly around the entire periphery. The suspended solids are nized material handling equipment, and an elaborate system for deposited during the filtration portion of the cycle and, after dust control. A comprehensive flow sheet of the Lompoc plant drying, a very narrow cut of the precoat diatomaceous earth and is shown in Figure 1. ,
Febmaxy 1953
INDUSTRIAL A N D ENGINEERING CHEMISTRY
2 59
CRWE UNUIAMNG HOPPE
URALPROOUCTS
’
CLEAN UP EXHAUSTER
BAGHOUSE EXHAUSTER MAIN PRODUCT PACKER
PACKERS+
uu
Figure 1. Flow Sheet for the Processing of Diatomaceous Earth a t Great Lakes Carbon Cnm.. Lomme. Calif.
INDUSTRIAL AND ENGINEERING CHEMISTRY
260
TABLEI v .
PROPERTIES O F Satural
DICALITC DIATOMACEOUS EA4RTH PRODUCTP Filter Aids Calcined
White
iXatura1
Fillers Calcined
White
Relative filtration rates, based o n natural with flow rate of unit value Wet cake density, lb./cu. it.
1 15-22
1-3 15-23
3-20 16-2 1
lil28
15130
15-40
sedimentation particle size Distribution, % +40 microns 20-40 microns 10-20 microns 6-10 microns 2-6 microns -2 microns
2-4 8-12 12-16 12-18 35-40 10-20
5-12 5-12 10-15 15-20 15-45 8-12
5-24 7-34 20-30 8-33 4-30 1-3
0-4 0-10 0-14 1-32 33-40 14-68
5-12 5-12 10-15 15-20 15-45 8-12
0-4 1-7 10-25 15-35 30-60 3-20
6.0 2.00 6.0-8.0 1.46
0.5 2.25 6.0-8.0 1.46
0.5 2.33 8.0-10.0 1.46
6.0 2.00 6.0-8.0 1.46
0.5 2.25 6.0-8.0 1.46
0.5 2,33 8 0-10.0 1.46
Moisture, max., 70 Specific gravity %%active index Gardner-Coleman oil absorption A.S.T.M. rubout oil absorption Retained on 325-mesh screen, Surface area b y nitrogen sdsorption, sq. meters/grain
...
...
0-12 12-40
...
...
0-12 2-5
... 12& 1-3
Vol. 45, No. 2
area and is then ahlc to loud material of the clcsired quality. The quarry supplies approximately 280 tons of ivet ore daily for processing into approximately 170 tons of 5iiikht:d product (Table i-). Crude Ore Contains 30 to 50970 Moisture; Density Approximates 22 Pounds per Cubic Foot
The crude ore facilitic- in the plant include equipment for unloading, crushing, stor130-170 130-160 93-160 ing, and feeding the diatoma130-160 130-160 130-160 ceous earth ore to the proc0-12 0-12 0-35 ess. Ore from the quarry is 12-40 2-5 1-3 delivered to the plant in twin, h o p p e r - bottomed trucktrailers, each bin containing 700 cubic feet or about 23,000 pounds per load (423). The material is usually 9570 through a l-inch mesh, but, occasionally there are lumps up to 12 inches in size. Moisture content ranges from 30 to 5070, and dry density is approximately 22 pounds per cubic foot. From the trailers the ore is dropped through a 10-inch grating to one of two 900-cubic feet underground V-bottomed unloading hoppers. A pan feeder 36 inches wide with a capacity of 750 to I500 cubic feet per hour carries the ore from the bottom of the hopper to a sloping troughed rubber conveyor (30 inches wide) which transfers the material to the crude ore crusher. This is a hammer mill with hopper opening of 24 X 28 inches which operates a t 900 r.p.m. and which delivers a product 100% through 2I/*-inch mesh, 99% through 1-inch, and 90% through 1/2-inch at a rate of approximately 50 tons of wet ore per hour ( 5 E ) . The discharge from the crusher is moved by a rubber conveyor belt, 20 inches wide, to the crude storage silo which is 20 feet in inside diameter and 18 feet high; its live volume is 10,000 cubic feet or about 260 wet tons. The sides of the lower part of the silo slope 60" to the horizontal and a t the bottom is a rectangular opening 20 feet long, 2 feet 8 inches wide, and 9 inches high fit,ted with a gate which is adjusted' manually to control feed. Four heavy duty vibrators are installed equally spaced around the sloped section and 6 feet from the discharge to prevent the crushed ore from bridging across and stopping flow (17E). The amplitude of vibration can be varied to provide for changes in moisture content. The silo feeds to a 36-inch pan feeder which has pans 9 inches vide and I inch deep (14E'). This feeder conveys the crude diatomaceous earth t'o a n 18-inch inclined rubber belt conveyor which terminates a t the discharge side of the first stage drying unit (KO. 1 furnace). A magnet removes :tnj- iron particles present. All convcyors in the crude ore handling tight enclosures. d l 1 electrical equipment is electricall?- interlocked.
I
Specifically, the entire air flow throughout the process was designed so that a negative pressure exists at all places where material is entrained for conveying. Although this fact resulted in the probability of increasing air leakage into the system with the resulting increased horsepower requirements, i t was deemed necessary, since a positive pressure would cause dust to be emitted in the air. I n addition, an installation is provided whereby a continuous change of air in the bagging area takes place so that fresh air is always present around the operators of the bagging machines. This installation was designed to draw approximately 40,000 cubic fcet per minute away from the bagging machine operator and, in addition, introduce a supply of air which is heated to 70" E'. T o enable good housekeeping in the warehouse area, a vacuum pickup system has been provided. The operation of this unit is similar t o a domestic vacuum cleaner. Dicalite Quarry Supplies 280 Tons of Wet Ore per Day Diatomaceous earth was at one time removed from the ground by undergound mining. I n most areas this has been replaced wibh open-pit mining or quarrying. Hand quarrying was common a few years ago but power equipment is chiefly used today. The Dicalite quarry is located a t Oak Tree Ridge, approsimat,ely 7 miles east of the Lompoc plant. Total holdings cover approximately 750 acres. The quarry has been in operation for 5 years and supplied ore to the company's plant at Walteria (165 miles south) before construction of the unit a t Lonipoc. The deposits are laminated in zones parallel to the plane of the major strat,um, which is inclined approximately 35" to the horizontal. Commercial ore is present in a 1 t o 3 ratio to ouerburden. The mining is done by power carry-alls with a lO'/a-foot blade that scrapes up the ore into a 25-cubic yard bin (9 tons) ( I E ) . Wet ore is piled a t the quarrj- and loaded as needed into trailers by a slusher which consists of a loading bucket and attached dragline operated by power driven drums (6.73). The loader locat,es the bucket on the desired section of the storage
Drying and Wet-End Processing 4re Accomplished in a Series of Heaters, Cyclones, and Separators
As late as 20 years ago, open-air d r j irig of the ore in fields as PRODUCTION OF PROCESSED CALCINEDPRODUCTS common in both the U. S. and foreign countries. Slabs aveiaging PER TONOF ORE 7 inches thick and l * / z X 2 feet across the face mere stacked in Raw Materials Pounds Products a n d Loss Pounds parallel walls in open, windy fields and dried by exposure for Diato'maoeous earth ore Sludge 35 3 to 8 weelis (6). The disadvantages of this means of drying (dry basis) 2000 Wet end waste 160 100 Finish end waste 150 are obvious. Centrifuging, humidified air dryers, tunnel dryers, Soda ash 3 l n i n nroduct and indirect heating by hot air have been used or considered by some producers.
TABLEV.
February 1953
INDUSTRIAL AND ENGINEERING CHEMISTRY
26 1
I h s t - T i g h t ( h n v c j o r s arc C s e d throughout Plant
Oier-all \ i e w of Grctli Lakes’ Plallt at Lonipoc, Calif.
\lain product storage bins, rarh w i t h a vnpncitt of 80
Final Separation and Classification Cyclones Dried earth from kiln is cooled in pneumatic cooler as i t is conveyed to finish-end cyclonest waste hopper is shown at right
totifi,
are
at
left
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Vol. 4% No. 2
~~
Figure 2.
Crude Diatomaceous E a r t h I s Purified in t h e Wet-End Trapping System
uicaiim cries me cruae ore in a cwo-stage Bssh drying system and removes foreign matter prior to calcination and fiiahing. Equipment in the wet-end seoticn includes cyclones and nepari+ torn, funuuza and air heatera, and a wet collector for removal of d u d before discharge to the atmonphere. Hent for the first stage of the drying circuit is provided by the No. 1 furnace, a directlired air heater (28E). T b is a cylindrical heater 16 feet long and 8 feet in inside diameta which tapera to a 00niOal end with a %foot discharge; it haa a capwity of lO,OOO,OOO B.t.u. per hour. The heater has a double lining consieting of 4'/2 inchen of insulating brick and 9 inches of firebriek. This furnace, as well as furnacea and air heaters further in the proceaeing line, are equipped with dual-fuel burners (ZOE) for oil or gas and 5 m e protective apparatua (81s). The duct for handlii combustion ga6ea from the heater is lined with 4'/, inches of 6rat-grade firebrick, up to the point where diatomaceous earth is intmdud. The combustion gases from the furnace, combind with hot gas discharged from the No. 2 cyclone (the function of which will be described), remove approximately 50% of the total moisture in the wet diatomaceoua earth. Primary air to the henter ranges from 200 to 4ooo cubic feet per minute at Bo" F. and secondary air, approximately 3600 cubic feet at 60- F. Dincharge temperature ranges from 500° to
vious as clay and decreaaea the rate of liltration of liquid through it. The centrifugal blower usad is denigned to handle 10 to 15 tons per hour (wet basis) or 25,000 to 3 5 . Wcubic feet of ore and &ases at 250' to 400' F. and in operated by a lOO-hp., 1203r.p.m., W v o l t motor (ZdE). The blower has s* mild steel bladae (% inch thick) welded to a 2530 carbon ateel spider attgohed to a shaft 3"/~6 inches in diameter. The blades are subject to 6evere erosion. The aiden of the blower (fabricated from %4nch mild steel) are lined with 1-inch A.R. steel WW plates and the %inch roundabout is cast from chrome molybdenum alloy to limit emmion of these parts. A door on the side of the casing is provided for periodic inepection and balancing of blower blades. Inasmuch as the blower (as well as blowers further in processing) in located after the furnace, a nafety device is provided to admit cold air in the event temperaturen exceed €& F. lo Fmm the blower, the hot gases and partially milled diatomacebus earth (85% through a25 mesh screen) pass through a %inch inaide diameter fluid-aolid heat transfer duct. Passage through thie duct provides sufficient time and turbulence to complete heat and mann transfer between solids and gases from the blower to the 6rst cyclone. Inlet temperature to the duct is 350' to 500' F.and exhauat temperature ranges from 135* to
1200" F.
l W F.
The ore from the d o in fed into the hot air stream and passes through the wet-end or No. 1 blower. While thia blower furniahes air for moving the diatomaceous earth through the system, it haa an even greater function of milling the material. It is to separate the individual foeails from each other without d& actually powdering them inasmuch as e x d v e milling, such as would occur in a ball mill, renders a product almost as imper-
Wet-End Trapping and Separating Systems Remove Fodign M a t t e r f r o m the Crude Ore The partially dried diatomaceous earth passes to the wetend trapping and separating sptema where foreign matter, consisting of stone and clay present in the crude ore, is removed by a system
'
February 1953
*+
-, >
INDUSTRIAL A N D ENGINEERING CHEMISTRY
263
of cycloncs and separators. No. 1 cyclone is 9 feet in outaide diameter tapering to a 24-inch discharge. Over-all height is k22 feet. The erosion of the cylindrical section has been miniby the u ~ of e '/,-inch Type 304 stainless steel; the conical m h o n 18 made from ' / h c h mild carbon steel. The cyclone is de&& for efficient operation with 2 to 4% of feed being exhausted and 96 to 98% being discharged. All cyclones are quipped with rotary seal discharge valves. All seal valves in the plant are designed with outboard bearings rather than with bearings located immediately adjacent to the valve bowing (ME). A seal is installed next to the housing, and considerably less wear and maintenance have been experienced as a result. The very fine exhawtA particles pass with combustion gasea to a wet-end collector. This effluent is corrosive because of pmducts of combustion (pH range from 7 to 3.5). The Winch duct between the cyclone and collector is fabricated of Type 304
stainless steel. The Dicalite Division has done a considerable amount of work to reduce the amount of dust discharged to the atmosphere. All dust-oollecting equipment is designed to keep the amount of discharge within the limits established by the Loa Angelce Air Pollution Control District. Although the plant is not under the jurisdiction of thin d e , Dicalite feels that these pollution control regulations could eventually be adopted in the plant area. Maximum permissible discharge of dust from the entire plant to the atmosphere is approximately 15 pounds per hour (under the La8 Angeles code). The company is attempting to keep total disoharge to 10 pounds per hour. Various standard collectors were teated for use in collecting dust from the exhaust of the No. 1 cyclone. The final installation is B modilication of the equipment used in the company's plant in Walteria, Calif. Two exhaustam, rated at 25,000 to 30,000 cubic feet per minute at 160° F. and operated by 25O-hp., 72h.p.m. motors, move the dusUaden stream to the dust collector. Ahead of the first fan, water is added a t a rate of 70 gallons per minute. This water wets the fan blades which offer a large impingement area, and water is also dispersed into very
fine droplets which further remove dust particles in the collector. The collector itaelf is a redwood tank, 10 feet in diameter and 28 feet high, which containe four-pass eliminator bafsee. Water is intrcdnced at the top of the tower, and clean air is discharged to atmosphere. The system removes approximately 0.15 ton per hour or 3 to 4 tons per day, which in conveyed to a sludge settling pond. The discharge from No. 1 cyclone stiil contains approximately 50% of its orb$nal moisture. Heat for removal of this water is provided by the No. 2 furnace, a directAred air furnace similar to the one previously described. This unit ia 10 feet in diameter by 20 feet long, and insulation is the m e as in the No. 1 furnace. Maximum operating temperature is 1700" F., and capacity is 20,000,000 B.t.u. per hour. The hot gases from the rotmy kiln (further in the processing system) are added to the combustion gases from the furnace and theae together evaporate the residual moisture in the earth. The combined gaace with the discharge from No. 1 cyclone pass through the No. 2 blower where the product is further milled. This centrifugal blower is o similar construction to the one pre viously described and bas a capacit: of 25,000 to 35,000 cubic feet per min ute at 400' to 700' F., and 10 to I! tons of wet product per hour. Thm hot earth then passes through a 27 inch diameter fluidalid heat transfer duct. The No. 2 cyclone collects the dr: diatomaceous earth for subsequent p m easing in the w e k n d separators. T b
I
unit is of the m e design and approximately the m e dimenMona .B the No. 1 cyclone but is constructed of '/rinch mild mrbon steel throughout. Approximately 2 to 3% of original feed is s*bausted and recycled through the No. 1 cyclone. The
cubic feet per minute. Each unit operatee as an inefficient cyclone with 95 to 98% of its dry feed e ~ h a ~ ~ t eThe d . waste is discharged through a seal valve to a l'/,-oubic foot hopper. The No. 3 cyclone collects the purified diatomaceous earth for subsequent proceasing in the kiln and tinish end. The cyclone is of the m e &e as those previously described and is constructed of l/rinch mild carbon steel. The purified, collected earth from this unit is approximately 90% through a 325-mesh screen. At this point, the material has an aerated density of 6 to 10 pounds per cubic foot as compared with approximately 22 pounds per cubic foot when it entered the fvst milling blower. It pasees thmugh a 24-inch seal valve at 250' to 400' F. to a hopper from which it can he fed to the kiln or to the kiln by-paas in the making of uncalcined products.
bslsnce is d i a o k g d through a rotary seal valve. Following the No. 2' cyclone, the dry diatomaceous earth in impure form pasees to the wet end trapping syatam. The purpase of this aection of the plant is to remove clay, mots, and sand which is indigenous to crude diatomaceous earth deposits. Their removal is mandatory prior to further p m & n g since, otherwise, high loases of diatomaceous earth result during caloining, h u e of fusion with the impurities, aa well 88 an exceasive consumption of soda aah and other purifying agents. This section essentially consiats of two separators equipped with ep&dly designed backwash air pots which are arranged in a c l o d circuit air system. These separators claesify the feed into a coarse waste and a fine product. Dry diatomaceous earth from the No. 2 cyclone is resuspended in an air stream maintained at temperatures from 250' to 450' F. This Stream then enters the primary separator. The hulk of the suspended material falls into a baoknash pot which permits the coarse material to paas into a collection chamber by resuspanding the fine material in the air ~tr- 80 that it pasaes through in the separator exhaust. The &e distribution in the exhaust as well as the discharge from the separator pot is controlled by the volume of the air introduced into the backwash chamber. A final separation is not obtained in this unit, and the exhaust stream from the first separator is reworked in the second unit. A relatively pure stream of airsuspended diatomaceous carth 18 obtained for feed to the No. 3 cyclone. The two m t e streams are combined and sent to a waste collection system. In order to control the temperature in this entire system, heat is provided by the No. 1air heater. This is a d i r e c & W unit similar to the furnaces previously described, but s d l e r in she. The nominal dimensions are 6 feet in diameter hy 13feet long with a gas discharge temperature of 2600- F. The maximum capacity of the unit is 3,500,000 B.t.u. per hour. The dry diatomaceow earth is picked up by this hot air stream and proceaeed through a 2Sinch line at approximately 7 to 10 tans per hour. Air is provided by a recycle gas blower through which p a s the hot gases from No. 1 air heater and the exhaust gases from No. 3 cyclone. A t this stage, the diatomaceous earth has been processed sufficiently to give it properties app m h i n g that of a fluid as far aa flow is concerned. A typical materisl balance aa well as the detail p r o m flow and operating conditions are shown in Figure 2. The unique separators are 51 inches in outside dinmeter and 137 inches in over-all height. A conical seation on the bottom tappers to a l%inch diecharge. The capacity of each unit is approximately l0,oOO standard
Calcination C h a n m the Filtration PmpEarth Pmduota
erties of Diatomacenus
Natural or uncalcined products, calcined products, and procesecalcined products are made a t Dicalite's Lompoc plant. However, approximately 90% of production is calcined or proceaa calcined. In the production of calcined products, materials from the No. 3 cyclone paas to the kiln by a 16inch, I&foot long ecrew conveyor at a rate of 9 to 10 tons per hour. The rotating kiln is 11 feet in inside diameter by 100 feet long and is similar to those used in the calcination of portlaad cement (29E). Shell thickneaa is inch, and kiln slope is inch per foot. The %inch lining is made of first quality Colorado refractory brick (7E). The kiln rotates at 1/2 to 2 r.p.m. and material flow is countercurrent to gas flow. Feed temperature is 300" to 100' F.; m i m n r n temperature of discharge is 2200" F. The kiln burner ($E)u8es either fuel oil (PS-300, rated at 148,000 B.t.u. per gaJlon) or natural gas (at 15 pounds per square inch gage and containing 1097 B.t.u. per cubic foot). Combustion air is introduced at 3900 to 5900 standard cubic feet per minute a t 60' F. Calcination results in a change in the filtration properties of diatomaceous earth products. Impurities which are not removed in the wet-end trapping circuit are converted to fused slam, such as aluminum silicate. These impurities are subsequently removed in the finish end trapping system. In addition, organic matter, which is frequently found associated with diatomaceous earth deposits, is removed by combustion. In 8Ome products, the effectiveness of calcination is further i n c d through the addition of a fusible, alkali salt a t a rate of 3 to 10% of the feed to the diatomaceous earth before calcining. This reduces the surface area per unit volume of the product. Caustic soda and sodium chlotide have been used .Bfluxing agents
264
4
Fi-
Euth
4. M
Photomicrographs Show Changes That Occur i n Diatomacenus t h r o u g h Racsssing S t ~ p (All Photos 2QOX)
It Pm-
separator. The function nf thia unit is to q l i t off part of the m s e material, c h i d y that picked up in the kiln, from the fritted particles formed during caloination. The separator, constructed of I/&nch mild steel plate, is 15 feat in over-all height and has a maximum diameter of 51/r feet. Approximately 60 to 70% of the feed is exhausted to the amndary separator. Thin unit further separates foreign matter, with 8 to 13% of original feed being removed. The mame discharge from the two separators is pioked up by another milling blower and fed to the tertiary separator. This unit is considerably smaller than the other separators (30inch inside diameter X 78 inchen high) and has a capacity of 31M) standard cubic feet per minute. This separator divides the remilled product into u clean diatomaceous earth stream, which is recycled to the secondary separator, and a c a a m stream (6 to 10% of feed of which 10 to 20% is minus 150 mesh) which is discarded as waste. After passing thmugh the secondary separator a second time, the diatomaceous earth ia classified into two product streamsa fine material, subsequently collected in dust-armting equip ment and a comer material, which is used chiefly in filter aids. This is accomplished in a product elasailier, a cyclone similar in siee and construction to the No. 3 cyclone. The exhaust (15 to 25% of the original feed) is made up of particles 90% of which are -10 microns in size and are used for fillers. The discharge drops to a screw conveyor which feeds to an elevator that empties into one of two galvanized steel bins each of which has a capacity of ahout 80 tons. The diatomaceous earth in the fineparticle stream is removed from air in a thrmection baghouse with a total filter capacity of 80,000 to 90,000 cubic feet per minute at BOo F. (13E). Finish End .Willing and Claasifyiag Each of the sections is 45 feet long, 10 feet wide, and lSL/rfeet Yields Final Filter-Aid Grade Material high, below which is a hopper 6'/* feet in height. Each section contains 900 Orlon stockings which collect the d i d material After dry in^ and/or calcining the diatomaceous earth io further (.$ E.) . O D e r a t i n a. p-aed in the finpreasurc is -2 to -3 ish end milling and inches of water, and c W y i n g section of a safety device PIP theplunt. A blower, venta the negative similar to those in the pre~surefrom buildwet end, with a c&ing up beyond 10 pacity of 22,000 to inches of water. Tem28,000 cubic feet per perature ranges from minute at 100' F., is 200"to250°F. The used to further mill baghouse is equipped the dry material at with automatic shskt h i s &age. ing equipment. A 9Thediwharee - from inch screw conveyor the milling blower a Is Centered in a Central Control Room carries the collected P . 4 mlltdm m-stie . u . M tm U . Pmce-dns qd-t pnsaes to the primary
in m n e plants. Dicalite adds soda ash, which is lower in cost and more convenient to handle, in making these pmducte. The material used is 99.18% pure, has a specific gravity of 2.48, and is prepared for une in the soda ash plant. Covered t N C h drop the soda ash to an undergmund hopper which feeds ta,a screw that discharges to a bucket elevator going ta the IOQ-tan soda ash ntarage silo. From the do, the soda ash drops to a 1 X 4'/r foot d p e r , with 2 X 2 inch holes, which removes oversieed lumps. Material passing through the scalper d r o p to an %inch e n c l d belt feeder that discharges to the soda ash mill. This a hammer mill with capacity of 1400 pounds per hour of soda ash with density nf 55 pounds per cubic foot ( I I E ) . Discharge ia 98% tamugh a 15omenh screen. The pulverized material drops onto the wet diatomaceous feed and then enters the drying circuit (3 to 1Oyoby weight). W o n of the fine particles near the center line of the %ilnresulta in the formation of l u m p up to I foot in diameter. These are broken up by a lump breaker consisting of I-foot hammers made of mangaoese steel mounted on a %foot diameter drum (Figure 3). Thew arm, rotating at 63 r.p.m., eatend into the kiln discharge chute and break up the lumps in order that they m y be aireonveyed through the rest of the syBtem. The discharge passes through B 27-inch inside diametor m l e r duct where vacpum is 2 inches of water. Thr product is now ready for further milling and c l d f y i n g . A kiln by-pass line ia provided for making undcined producte. A Becond air heater (5'/, feet outside diameter and IO feet long) with a capacity of 4,760,000B.1.u. per hour furnishes heat when the kiln is not used in p r o r b n g .
c
265
.
266
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 45, No. 2
line. Two oil storage tanks provide a total capacity of 52,000 gallons. Electricity is purchased at 12,000 volts which is stepped down through a 2000-kv.a. substation to 480 volts for plant distribution. A steam generating station is rated a t 2760 pounds of steam per hour a t 140 pounds per square inch gage. Services required per ton of product are shown in Table 1-1. Control and Instrumentation Are Centralized
Finished Product Is Sacked in 50-Pound Multiwall Paper Bags material to the baghouse product storage bin (2000 cubic feet capacity). The interior of this bin is coated with a 0,005-inch layer of pure zinc to prevent contamination of product. Two exhausters, with rated capacities of 53,000 and 33,000 cubic feet per minute, discharge the rlean air and gases t o the atmosphere.
Processing steps are controlled from a central control room. Here one operator controls all the drive motors for the flash drying, separating, calcining, finish end milling, and classifying equipment. Equipment in the crude ore, soda ash, and blending and bagging departments are essentially controlled a t an operators' station in the respective areas. Complete interlocking is provided for all the motors in the latter three groups. Positive sequence interlocking is provided o n the conveyor system feeding ore and soda ash to the process. Kiln feed conveyors, waste conveyors, and product conveyors all have sequence interloclcing. The control scheme is made up of a start-stop push button for the last conveying equipment motor in each group (dOE). Instrumentation is provided for full process control, and an instrument alarm panel is located in the main control room to warn if a n y processing variables exceed the minimum or maximum permitted. A siren is automatically activated when a n y piece of equipment fails or is overloaded. Control instruments (823)and alarms are listed in Table 1-11, Modern Winemalcing Requires Filter Aids in Each Processing Step
Through proper selection of ore and control of processing variables, nine principal grades of Dicalite filter aids are produced; these cover a wide range of industrial filtration requirements. The flow rate of each product, which is indicative of its specified performance qualities, is shown in Figure 5 . I n addition, other filter-aid grades are produced for special functions in specific TABLE VI. UTILITIESREQIJIRE~IESTS PER To;v O F PRODUCT industries. A typical example of these is Dicalite 211, specially Electricity,,kx .-hr. 223 processed for removal of small quantities of lubricating oils Water, gal. 1050 Gas, cu. f t . 690 from steam condensates. Another is Dicalite 7, used in the cleanOil, gal.' 49 ing industry, in which a n additive renders the solvent conductive a For cooling a n d wet collecting only. and prevents build-up of static electricity charges which cause Oil used only during winter months or n h e n gas supply is curtailed. attraction between garments being cleaned and particks of dirt being removed. Table VI11 lists typical industrial filter-aid uses, grade of A pictorial iepresentation of the process is shown in Figure 4. I t illubtrates the changes in physical structure which have occurred during processing of the dlatomaceoue silica. From the storage hopper, also zinc coated, flow is controlled through seal valves to one of three bagging machines, each of which has a capacity of 4 to 5 tons per hour (15E). Finished product is filled into 50-pound paper bags. A separate set of three similar bagging machines packs materials from main product storage bins. Filled bags are cleaned by air from a row of high velocity air jets and conveyed to a bag stacking and palletizing press (923). This consists of a n enclosure, 40 X 54 inches, sized to hold a full pallet of 27 to 42 bags, three on each layer, with the retaining walls shaping the pallet evenly as i t is stacked. A hydraulic ram with 111/2-foot travel and operating at 4 pounds per square inch compresses the full pallet, which is then moved to the warehouse by fork lift trucks. All water used in the plant is from company-owned wells, A storage tank of 100,000 gallons capacity is provided. Gas is supplied by a public utility company through a 6-inch supply
'
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
Febrtlary 1953
. 1
-.
F
267
product recommended for the wecific application, and average amount of filter aid added. The actual amount added v h e s i n m u c h as the filterability of liquidn varies with the amount and character of BUS pended solids to be removed. A "Nk of the thumb" guide is to add to the mother liquor an amount of filter aid equal to the weight of solids present to be removed. UEUally laboratory and pilot tests are Bufficient to detennioe proper lilter aid for each application. The test methcda developed by Great Lakes Carbon are demribed in the Instruction Manus1 for Bomb Filter Filtration Testa (9). Three schematic p m e s s diagrams Filter Schematic Arrangement of P-at are down in Figure 6 illustrating widely di5erent Xdustriw employing diatomaceous earth 88 a filter aid. keyed to the use of this type of filtration in virtually each step In each instance, the uee of diatomaceous earth is indigenous to in the processing of the fermented juice. This juice is filtered the production of B quality product under present maas prodncto remove insoluble tartrates, yeast cells, and coloring matter. tion techniques. The entire modem winemaking industry is The first filtration step is followed by blending various motha liquors and refrigeration d t i n g in the precipitation of tartrates and other mluble d t a which would be objectionable TABLE VII. INSTRUMENT CONTBOMIN CENTBALCONWL in the finished wine. Accordingly, a Becond diatomaceous earth ROOM liltration is made. The wine is then pasteurized to remove Typs Iwtrumant Function an excess of alburpinoids and proteins and to kill wine yeast and Temperstue recording cootrollem bacteria. A third diatomaceous earth filtration is used to remove (wteotiometu typo) these materials. During aging, additional precipitation mmeNo. I furluros controla tamperatura of Grst e t q e O f milling and dryinp cimuit: also adlusts fueltimes occur8 which may cause cloudiness, and thia is removed by air ratio No. 2 furme Controla h p e r a t of second ats e of a final filtration. milling and buing aircult: alao &uta A major application for D M i t e filter aids is in the filtration of washed ~ugarsirup prior to char decolorization. Solids removed in this step tend to plug the char bed and reduce ita decolorization efficiency. In most refineries this step removes defecation agents such BB lime and phosphoric acid. Dicalite filtration also playa an important part in the purification of affination sirups in refineries that produce table sirups and mft sugars. Dicalite is widely used in the pharmaceutical field, and a typieal . example is the production of penicillin. The Dicalite filter aid typodampear - E%homesD-ursPrev.ntas=-vanegstisspraauminbs is employed following the fermentation of the penicillium notatum h o w thou h operation of a aolenoi!: o p e d coli air inlet mold. The liltration step removes the mold and results in a clear Temperature indiuting contro era filtrate from which the penicillin is extracted. Dicalite filter (wtantiomater type) No. I blower %"en& exo-w tampratby openaids are again used in the purification of the extracted penicillin. ing oold air b l e d at inlet No. 2 blower
No. 1 furnace refrso-
tow
Temperature rocorders (Potaptiomstar tupe) Dew point Multiwint recorder
Preventa si-ive temperatby opening cold air b l e d a t inlet PIevante exceadve rsfrsctpry tamwaratura by activating visible and audible alarm
Recorda dew mint at diacharaa of No. 1 FYOlone temperatUP to ".many as !2 pom9 throughout profar specral studlea
Alarm 8mmm Electronic
s r a h o w discharge ataok
hter Rsssvrr b v e l indioatora B..houao Temperature suholum
Millin. blowem
A o t i ~ t c aalarm when dust exow& Eoncantration alarm ininairD ( l s ~
fired
ia oltin.
aviahed
~~etivates rlprm when madmum level in aoeded biM and M exActivate alarm when there is deuarture from norms1 nezpativa operating prew
e-
& ,,, 250' F.
temwrat-
an;oeds
Alarm -tinted when tamwratum em& 800- F.
Research a n d Development Activities Continue to Provide New Applications for Diatomaceous Matarids Diatomaceous silica products have become accepted processing and construction materials in widely diversified xypes of industrial olanta. With few exceotions. a n annlication of diatomaceous materkds once developed into major proportions has never dedined appreciably. One factor that cannot be evaluated or charted in the growth trend is the accelerating inEuence exerted by the research and development activities of the major producers in seeking new applications for their praducts. Great Lakes Carbon maintains a divisional research laboratory a t Walteria, Calif., as well 88 ita central research and development division at Morton Grove, Ill. Both laboratories carry on extensive research and development activities related ta diatomaceons earth, filter aids, fillers, and related products. In addition, Great Lakes Carbon cooperates with the development laboratories of industrial m. Filter aids account for the major portion of diatomwmus earth
..
268
INDUSTRIAL AND ENGINEERING CHEMISTRY
-.gun6. Diatom.eco&sEarth FilL. -.ds
production. They have dominate$ industrial filtration for many yearn, and although other types are used to varying extent, none appaan to be in a challenging position in the foreweable future. It ia in the ~Wdeof filtration and insulation that the outlook in most pmrniaing for future applications. h o major filtration fields showing pro& are in the PICd d o n of antibiotics and in water purification. The latter diem a large potential market for diatomaceous earth filter aide. It includen filtration for reclmtion and recycling of water used in m y industrial processee, for prevention of pollution in dispmal of waste water, and for purification of domaetic and induatrial water supplies. Tonnage of filter aide ,ye4 for t h i s purpoee has grown rapidly in the last 6 years. Two apecilic casea are filtration of white water in papezmiUaforrecycling, largely reducing water 'consumption and stream pollution, and filtration of slop oils in petroleum refineries to remver oil and to prevent stream pollution. There are- a number of divendfied applications of Did t e pmducts as industrial 6Uers. In addition to more commonly known uw, such as pigmen&fillers in many paper pmducte; extender and Batting agent in paints, varnishes, enamels, and hquera; and the aolid filler for gas cylinders; there are newer developments . such as cstalyst carriers and as I
~
Are Used
.- ..'id+
Vol. 45, No. 2
Diversified Industriea
anticaking agents in chemical fertilizers. Application of diatomaceous materials has become extensive in the latter field with the most rapid growth in the last 4 or 5 years (16, IS). A still more recent development is the use of diatomaceous earth as a component in latex-glaas fiber separators for storage batteries. These separators contribute greatly to i n c d battery life and are expected to become the most widely used type of separator. A type of Dicdite material which might be called a "specialty" is Demoiat, a desiccant. It was orig?.nally developed for the purpose of rust prevention in ahipmenta of war machinery and equipment during World War I1 and now is sold nationally by
Weipht %
Uad
0.24.8 0.5-1.5 0.14.2 0.2-2.0 0.2-2.0 O.MW.2 0.14.2 0.14.16
O.Oa4.M 0.24.4
0.1-0.8 8.0-5.0
0.w14.1
o.ozw.1 0.01-0.6
0.0084.2 I/JlW lb.
.
wm(mr.ta
"*S 0.1-2.0 0.1-2.0
February 1953
INDUSTRIAL AND ENGINEERING CHEMISTRY
ratail outlets to leduce dampness in home basements and closets. Demoist also has various industrial applications related to its high moisture-absorption capacity. Although extensive deposits of good quality crude diatomite are known to exist in other countries, processing of diatomaceous materials is neither as evtensive nor as advanced abroad as i t is in the Unit6.d States. As a result, there is considerable export of products made in the Gnited States. The potential foreign market is considerably greater than that indicated by export sales, however. The principal reason for this is t h a t the domestic demand for diatomaceous materials has increased phenomenally in the last decade a n d the products have been in short supply three times during that peiiod. World War I1 started a significant upsurge of demand. The current international situation, requiring production of foods and other goods at a high level to meet defense as well as home needs, has made the latest shortage serious during the last 2 years. Increased current production, however, should permit more extensive development of the foreign market. Acknowledgment The authors gratefully acknowledge the aid given during the preparation of this manuscript by T. E. Burns, R. L. Douglas, and P. W. Leppla of the staff of Great Lakes Carbon Corp. I n addition, the cooperation of George Havas, general manager, bnd L. H. Oppenheim, assistant general manager, and technical etaff of the Kaiser Engineers, Oakland, Calif., is appreciated. Literature Cited (1) Boyd, R., and Schmidt, R. W.,IND.ENG. CHEM.,34, 744-8 (1942). (2) Calvert, R., “Diatomaceous Earth,” p. 18, American Chemical Society Monograph, New York, The Chemical Catalog Co., Inc., 1930. (3) Ibid., pp. 23-8. (4) Ibid., pp. 28-33. (5) Ibid., pp. 76-80. (6) Ibtd., PP. 108-34. (7) Finnell, J. E., Harrison, M~ A., and Schmidt, R. W., M o d e r n Brewery A g e , 23, No. 3, 89-94 (1940). (8) Frankenhoff, C. A., IND. ENG.CHEM.,34, 742-4 (1942). (9) Great Lakes Carbon Corp., Dicalite Division, “Bomb Filter Filtration Tests,” Instiuction Manual. (10) Haffnei, L. C., and Kobe, K. A., PaczJic P u l p & Poper I n d . , 19, NO. 1. 49-52 (1945). (11) Hall, H. W., Paint, O i l , a n d Chern. Rea., 100, No. 8, 16-20 (1938).
269
(12) Halvorsen, 0. G., P a p e r T r a d e J., 125, 37-40 (Oct. 30, 1947). (13) Halvorsen, G. G., T a p p i , 35, No. 4,114A (1952). (14) Halvorsen, G. G., and Bollaert, A. R., IND.ENG. CHEM.,38, 385-9 (1946). (15) Hardesty, J. O., and Kumagai, Rikio, Agr. Chemico,Zs, 7, No. 2, 38-9, 117-19 (1952). (16) Ibid., NO. 3, 55, 125-9. (17) Kenney, J., W i n e s a n d V i n e s , 21, No. 9, 20-2 (1940). (18) Ibid., NO. 10, 20-2. (19) Kent, R. D., S u g a r , 36, 25-30 (May 1941). (20) Kern, E. A., and Kern, H., M o d e r n Brewerg Age (April 1946). (21) Schmidt, R., and Harrison, M. il., Facts A b o u t S u g a r , 33, 559 (1938). (22) Schmidt, R. W., and Konney, J., W i n e Rev., 9, No. 3, 36 (1941). Processing Equipment Caterpillar Tractor Co., Peoria, Ill., DW-20 tractor with No. 20 scraper. Coen Co., San Francisco, Calif., special 12-inch combination gas and oil kiln burner assembly: Du Pont de Nemours & Co., Inc., E. I., Wilmington, Del., Freon type 417. Fruehauf Tractor Co., Detroit, Mich., hopper-dump trailers. Gruendler Crusher and Pulverizer Co., St. Louis, Mo., crusher 3XC. Joy Manufacturing Co., Los Angeles, Calif., Model CF-312 Sullivan Joy 3 drum scraper hauler. Laclede-Christy Co., St. Louis, Mo., Cal Brand refractory bricks. Minneapolis-Honeywell Regulator Co., Minneapolis, Minn., recording controllers. Moody, Sweasy, and Rowe, Oakland, Calif., pallet press. North American Mfg. Co., Cleveland, Ohio, oil-gas dual feed burners. Pulverizing Machinery Co., Summit, N. J., No. 3TH Mikropulverizer. Rees Blow Pipe Mfg. Co., San Francisco, Calif., special centrifugal blowers. Ibid., compartment type dust arrestor. Stephens-Adamson Mfg. Co., Aurora, Ill., Style E apron feeder. St. Regis Sales Corp., San Francisco, Calif., Type 105VF vertical shaft type packers. Sutor-Bilt Co., Los Angeles, Calif., seal valves. Syntron Co., Homer City, Pa., Syntron vibrator Model v200. Thorpe, J: T., Inc., Los Angeles, Calif., direct-fired air heater. Traylor Engineering and Mfg. Co., Allentown, Pa., rotary kiln. Westinghouse Electric Corp., Los Angeles, Calif., electrical control centers and push button panels. Wheelco Instrument Co., Div. Baber Colman Co., Rockford, Ill., Wheelco Flame-o-Trol No. 1301.
Research and Development Division, Great Lakes Carbon Corp., Morton Grove, Ill.
