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concentrated. One mill has been erected at Gainesville, Fla., which is probably capable of handling all the fruit that will be produced in that area for some years to come. The plant represents an investment of about $15,000.00 and has a capacity of 50 gallons of oil per hour. The rate of intake is approximately 3000 pounds of fruit per hour, which is sufficient to supply an additional oil-pressing unit of the same capacity as that in operation at this plant. The entire operation is automatic from the delivery of the whole fruit to the decorticating machine to the production of the oil. The husks are of little value, although they may possibly be used for adding humus to the soil. The press cake contains very little oil and has some value as a fertilizer. YIELDSOF OIL. Some individual trees, after seven years of growth, have given yields of up to 2 gallons or more, which would indicate 200 gallons per acre. This, however, is unusual and could not be expected as an average figure for a whole grove. It is probable that a yield of 50 gallons per acre from groves ten years of age would be sufficient to justify the planting of such groves in a large way. However, under fortunate climatic conditions and with good soil and drainage
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it is probable that considerably larger yields will be shown, but none of these figures will apply unless proper soil and drainage are supplied. ACKNOWLEDGMENT The writer wishes to express his appreciation for the cooperation given by C. C. Concannon, chief of the Chemical Division, Bureau of Foreign and Domestic Commerce, United States Department of Commerce, in furnishing during the last eight years monthly cable reports on the exports of tung oil from China, and in other ways. Julean Arnold, United States Commercial Attach6 at Shanghai, China, has also been of service. The Department of Commerce now has in preparation a publication on tung oil which should be of great value in stimulating the development df this new industry which promises to be an important activity for the Gulf Coast region of the United States. RECEIVED March 8, 1932. Presented before the Division of Paint and Varnish Chemistry at the 83rd Meeting of the American Chemical Society, New Orleane, La., March 28 to April 1, 1932.
The. Tennessee Copper Basin EMERSON P. POSTE,P. 0. Box 51, North Chattanooga Station, Chattanooga, Tenn.
R
EFERENCE to a map of the territory formerly occupied by the Cherokee Indian reveals the fact that many present geographical names are of Indian origin, often honoring some prominent chief of the early days. One of these worthies by the name of Duck is commemorated in the name “Ducktown” which refers not only to a village but to the surrounding district which has long since become well known as a copper-producing area. I n more recent years the manufacture of sulfuric acid and other by-products has been developed to such an extent as to make this territory a center of chemical as well as metallurgical interest. GEOLOGICAL FEATURES The Copper Basin is located in the extreme southeastern corner of Tennessee, bounded east and west by two ranges of mountains approximately five miles apart. To the north is a lateral ridge, five miles south of which the Ocoee River cuts across the district. I n the Basin the formation is metamorphosed sedimentary material of Lower Cambrian origin, with some small igneous bodies. The ore deposits are enclosed in the sedimentary rocks as calcareous replacements, the source of the mineralizing solutions being unknown. They lie at an average angle of about 30” from the vertical. The lodes contain three distinct zones of ore. The outcrops are typical gossans with hydrated iron compounds predominating to depths of 100 feet. Below this zone is a layer of secondary enrichment high in chalcocite, locally termed “black copper,” containing from 20 to 40 per cent copper. Some free metahc copper is also found in this portion. Below this is a body of “yellow” sulfide primary ore extending beyond depths of exploration. The copper content of this material ranges from 1 to 2.5 per cent.
HISTORY OF DEVELOPMENT Based on Indian relics discovered near the Ocoee River in
1880,it is reported that the red men may have carried on some
early metallurgical operations, for with their pottery and other items, pieces of copper ore and slag and a slab of metallic copper were found. But the presence of copper ores does not seem to have been known to the white settlers until the late forties. There was quite general prospecting for gold throughout this territory in the early days, and, while panning a t what is known as the Burra Burra lode, one of the searchers found copper minerals which attracted attention. No systematic exploration was made, however, until 1847 when about 15 tons of ore were shipped to a refinery in Boston, yielding about 25 per cent copper. The same year an effort was made to use ore from another gossan in the manufacture of iron, but the quality of the product did not prove encouraging. Definite mining did not begin until 1850. The ore was hauled out by wagon to Dalton, Ga., a distance of 60 miles, and shipped to northern smelters. I n 1853 a road was constructed along the Ocoee River bed to Cleveland, Tenn. (a distance of 40 miles), affording favorable railroad connections, and by the latter part of 1855 the industry had taken on considerable proportions. During these early years several companies had been working, and many small mines and five local smelters had been constructed. The rich black ores produced a matte which found a ready market at the northern refmeries. I n 1858 a combination of the small companies took place, and a refinery was built in Cleveland. This was, in time, followed by a rolling mill and wire works, and a good volume of copper products resulted. Records vary as to the Civil War period. Some indicate that operations were suspended until 1866; others state that the district “supplied nearly all the copper used in the Southern States from 1861 to 1865.” It is evident that important reorganizations and rapid developments took place during the period 1866-77. New smelters were constructed; narrowgage tracks took the place of less adequate means of haulage; equipment in general was greatly improved. But the rich black ores were becoming exhausted. The poorer ores could
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not be worked profitably in the face of declining copper prices. Financial difficulties and legal litigations combined to effect idleness from 1879 until 1890. Renewed activities followed the construction of a railroad into the Basin and the improved metallurgical methods by which the poorer ores could be more profitably worked. Developments of this period led up to the organization of the two companies now operating in the Ducktown district. I n 1890 the Ducktown Sulphur, Copper and Iron Company began working the deposit a t Mary mine and developed methods for producing sulfur, copper, and iron. A Herreshoff furnace was put in operation at the Isabella plant. Meanwhile the limonite ore of the Isabella gossan was distributed to southern furnaces. I n 1894 two Herreshoff units were treating about 200 tons of copper ore a day. Large roasting sheds were constructed and by 1901production reached 3,000,000 pounds per year. Later it became necessary to discontinue open roasting. Larger furnaces were built and a plant constructed to produce sulfuric acid from the fumes. During the period 1897-99 developments leading to the formation of the Tennessee Copper Company took place. A new smelter was constructed at Copperhill to handle ores from the Burra Burra and London lodes, and extensive roasting sheds were operated. Large-scale production made possible the economic use of the lower-grade ores, and in 1903 over 10,000,000 pounds of copper were marketed. I n 1904 heap-roasting was discontinued, and later a sulfuric FLOWSHEETFOR PROCESS OF TENNESSEE COPPER COMPANY acid plant was installed. It is estimated that through 1920 a total of nearly 400,000,000pounds of copper had been produced in the Duck- Tennessee Copper Company operates the Burra Burra and town district. The mining of gossan ore was discontinued in Eureka mines, and the Ducktown Chemical and Iron Corn1907, approximately 1,500,000 tons averaging 43 per cent iron pany is producing from the Isabella mine. A separate having been shipped. Though the ores contain values shaft, known as McPherson, is a second entrance to the Burra in gold and silver, these values were lost prior to the use of Burra lode. electrolytic refining. There are considerable amounts of zinc The largest producer is Burra Burra mine from which the present, but until very recently they were lost. The principal normal daily output is 1400tons. This mine is a t the northern by-product has been end of the d i s t r i c t . s u l f u r i c a c i d , and I n the M c P h e r s o n methods which have shaft, w o r k i n g s are been worked out for being carried on a t u t i l i z i n g low-grade the 2000-foot level, eulfurous fumes are a the d e e p e s t in t h e definite contribution Basin. to c h e m i c a l t e c h E u r e k a a n d Isanology. bella m i n e s are in The present operathe same d e p o s i t , tors in the Basin are on either side of the the Ducktown Chemiextensive l i m o n i t e ca1,and I r o n Como p e r a t i o n s of the pany with office and o riginal gossan. works at I s a b e l l a , These mines are relanear Ducktown, and tively shallow, being the Tennessee Copper worked a t a maxiCompany with plant m u m d e p t h of 400 headquarters a t Copfeet. perhill. DUCKTOWN CEIEMICAL AND IRON COMPANY
PRESENT MIhTNC OPEFZATIONS Although more than fifteen mines are on record, only three are now i n active production. The
FLOWSHEETFOR PROCESS OF DUCKTOWN CHEMICAL AND IRONCOMPANY
All of t h e o r e s treated are reduced b y t w o s t a g e s of c r u s h i n g to a size
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Aoid Plant No. 2
Smelters
Power House
Add Plant
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THE
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In further preparation for the contact plant, gases pass of 0.5 inch and under, followed by wet-grinding in liardinge mills to under 60 mesh. Fineness is controlled by a ttirough coolers to remove excess humidity, followed by treatDorr classifier. The pulp containing 35 per cent solids ment in scrubbers tlirough which 45” acid is circulated. To passes through alkaline flotation cells, supplied with pine oil, remove the “mist,” the gas is drawn through another Cottrell creosote, and xanthate, for the separation of rougher copper separator, and then through a drying tower operating on 93 concentrate containing from 6 to 8 per cent copper. This per cent sulfuric acid. Then follows the blower which delivers material is further ground in rod mills and passed through the gas to the contact plant. The contact units are three Selden heat interchanger another alkaline flotation circuit to produce find copper concentrates (mainly chalcopyrite) containing from 15 to 17 converters installed by the Chemical Construction Company. per cent copper. The tailings from the rough copper separa- Counterflow of incoming and outgoing gases effects thermal tion go through an acid flotation system for the recovery of efficiency. Each converter contains 7500 pounds of contact iron concentrates (mainly pyrrhotite). The tailings from m a s s 4 per cent vanadium pentoxide. Absorption is this operation pass a magnetic separator for the recovery of effected in 20 per cent oleum to which pure water is added to magnetite which, with the pyrite tailings from the final copper produce 98 per cent acid. The waste gases going to the flotation cells, is filtered to proiuce combined iron concen- atmosphere are free of sulfur trioxide. The rated capacity of the plant is 120 tons of 100 per cent acid per day, and the trates for roasting. The copper concentrates are filtered out, sintered, and put conversion efficiency is between 97.5 and somewliat over 98 through a blast furnace producing a 35 per cent matte. This per cent. An elaborate system of control centers in a panel board on is reduced to blister copper in converters and sold to which are mounted Bron-n recorders and indicators for electrolytic refineries. The iron concentrates are treated in Herreslioff roasters, temperature at various points in tlie converters, Englehard and the calcines are burned to iron sinter known as arti- recorders for percentage of sulfur dioxide in gas entering the ficial iron ore, which finds a ready market a t iron blast fur- system, and Leeds and Korthrnp recorder for the strength of the finished acid which is held between 98.0 and 98.5 per cent. naces. Sulfur gases from the copper sintering and blast furnaces I t is possible to operate the plant at high efficiencya t 50 to 150 and from the Herreshoff roasters go to the sulfuric acid per cent of the rated capacity. The contact mass has been in steady use since January 1, plants. The gas contains from 6 to 7 per cent sulfur dioxide 1931, and shows no loss of efficiency. It is particularly free and from 13 to 12 per cent oxygen. Upon entering the acid plant, the gas passes through from the effect of any “puisons.” Much of the pumping Cottrell precipitators operating at a voltage of 90,000 to system is served wit11 Meehanite equipment. This metal has 150,000. The recovered flue dust Roes to the iron sintering heen in steady use in pumps for 98 per cent acid for 11months, furnace. A portion of the purified gas stream is conducted to conditions fatal to cast iron in from 1 to 2 weeks. On 105 the chamber plant, and the balance is firrther treated for the per cent acid, parts show no serious effect after use for 9 months. contact proccss. The products of tlie acid plants include the following grades The chamber plant consists essentially of one 24 X 24 foot Glover tower, 40 feet high, chambers totaling 1,000,000 of acid: 40 per cent oleum, chiefly used in explosives; 20 per cubic feet in volume, and six Gay-Lussac towers. Nitrogen cent oleum, under 0.002 per cent iron content; 98.5 per cent oxide gases are obtained by the oxidation of ammonia by one textile acid, largely used in oil refining and other chemical of two Chemical Construction Company units. Air is draw-n industries; 66’textilc acid, made by cutting 98 per cent; and through ammonia liquor, picking up the ammonia. The gas 60” chamber acid (under 0.004 per cent iron), for fertilizers, is then dried and heated by passing through a heat inter- pickling, and other commercial uses. Both chamber and changer in going to the catalyst. The capacity of the chamber contact acids are free from arsenic. The finished acid storage tanks total 60,000 tons capacity. plant is 350 tons per day.
I N D U S TI< I A L A N D 1': N G I N E E It I N G C €1 E M I S T K Y
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Laboratory SEE COPPER COMPANY
Bere used in the construction. The two Glover towers are each 50 feet high and 30 feet in diameter. The gas flue from The major portion of the ores from the Tennessee Copper the Glovers to the cooling chambers is 10 X 20 feet, and is Company's mines is separated by flotation, while a lesser 120 feet long. There are six cooling chambers, averaging amount is smelted by the direct or semi-pyritic process. 40 x 10 X 68 feet. The combined fan capacity is 150,000 Following the required crushing and grinding, the ores cubic feet per minute. The subsequent chambers are as treated by flotation are processed in an alkaline pulp for the follows: twelve chambers are 50 X 50 X 70 feet; six chambers separation of copper suEdes, the tailings from which are are 50 X 50 X 75 feet; and eight chambers are 23 X 50 X 80 further separated by flotation to produce zinc and iron con- feet-a total volume of 4,000,000 cubic feet. There are ten centrates. The zinc values are sold, while the copper and iron Gay-Lussac towers: four are octagonal, 19 feet in diameter, concentrates are further processed locally. and 70 feet high; four are round, 36 feet in diameter, and 65 The smelting process is carried out in two stages. In the feet high; one is round, 20 feet in diameter, and 50 feet high; initial charge, silica and coke are included with the ore which is and one is q u a r e (22 X 22 feet) and 64 feet high. The smelted in blast furnaces to make amatte containingabout 14 capacity of this plant is 930 tons per day. per cent copper. The melt is run into settlers from which the The smaller plant 2 involve8 one Glover tower, 30 feet in slag overflows, and the matte is drawn into ladles and, with diameter and 50 feet high; four horizontal chambers (236 X the addition of silica, is ready for treatment in the converters. 59 feet), 40 fcet high; and three Gay-Lussac towers in one The matte from the blast furnaces and the copper con- block, equivalent to total dimensions of 64 X 72 feet and centrates from the flotation plant are proceased in basic lined 44 feet high. The total chamber winme is over 2,000,000 converters, and the resulting blister copper (99.4 per cent cubic feet, and the capacity 470 tons per day. pure) is cast into pigs and shipped to refinezies in the north. Both plants are supplied with nitrogen oxide gases from an The total output approximates 2,000,OoOpounds per month. anhydrous ammonia oxidation installation of the Parsons type Some shot copper for the making of copper sulfate is also furnished by the du Pont Company. produced. By means of a system of controlling the sulfur dioxide ratio The iron concentrate is treated in Wedge roasting furnaces, between the chambers (devised by A. M. Fairlie), the plants and the resulting oxidized iron calcine is sintered in a are operated under varying conditions so as to maintain a Greensult machine to form a 64 per cent iron sinter which is constant sulfur dioxide percentage of 0.1 per cent in the gases sold to blast furnaces. This material is low in sulfur and entering the Gay-Lussac towers, a conversion efficiency of 98.6 phosphorus and, owing to its mechanical structure, is a very per cent. desirable raw material for the manufacture of pig iron. In addition to the chamber plants there are two large tower The slag from the copper blast furnaces is crushed or concentrators and one drum concentrator, heated by fuel oil. granulated and marketed for ballast, road dressing, and The water vapor and mist from the concentrators are passed concrete filler. through a scrubber for the removal of the former, following Gares from the blast furnaces and converters go direct to which the mist is removed by means of a Cottrell system the acid plant, while those from the roasters are cleaned by operafmg a t 75,000 volts. The capacity of the concentrators means of Sirrocco centrifugal separators. The sulfur dioxide is 180 tous per day. Two grades of concentrated acid are content of the gas is about 7.5 per cent. produced-a 66" commercial acid and a 66" textile clear There are two separate acid plants with a combmed output product. The finisbed acid storage tanks have a total of 1400 tons of chamber acid per day. The total chamber capacity of 30,000 tons. Four grades of acid are marketed: GO" chamber, chiefly to volume is well over 6,000,000 cubic feet, constituting the the fertilizer trade; 66" commercial concentrated, to oil largest single sulfuric acid operation in the world. Acid plant 1 was built in 190&10 and plant 2 in 1916; refineries .and other heavy chemical industries; 66' textile; the former is the larger. Nearly 8,0oO,wO pounds of lead and battery acids ranging from 1.225 to 1.835 in gravity. TEXNEBSEE COPPER
COMPANY
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ACKNOWLEDWENT I n the preparation Of this paper free has been made of United States Geological Survey Professional Paper 139, “Geology and Ore Deposits of the Ducktown Mining District,
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Tennessee.” The majority - - of the information has been obtained from the management of the two copper companies whose cordial coaperation is gratefully acknowledged. R~~~~~~~ February 25, 1932.
Cellulose in Industry HERVEY J. SKINNER,Skinner and Sherman, Inc., Boston, Mass.
C
ELLULOSE is one of our most important raw materials and one which enters, by way of its many ramifications, into the daily life and routine of every individual. Cellulose is the essential constituent of all vegetable tissues and fibers. It is the chief raw material of the textile and paper industries and more recently has become the raw material from which a wide variety of new products are made. The sources of cellulose are legion and may be classified in a number of ways. A classification according to the part of the plant from which it is derived will perhaps be first in order so as to present a proper picture of the many varieties of cellulose : First, there are the seed fibers which are borne on the seeds or on the inner walls of the fruit or capsule. Cotton is the principal and by far the most important member of this class which also includes kapok and other flqsses or silk-cottons. Second, there is the cellulose in the fihers of which the inner bark or bast tissue of the plant stems is composed. As these fibers appear in commerce, they are not individual cells like the cotton fiber, but are aggregations of numerous small elongated cells, the so-called ultimate fibers. In this clam we find flax, hemp, jute, ramie, and other grasses, such as the cereal straws, cornstalks, sugar cane, and esparto. Third, there are the fibers which are ot&ned from the leave3 of the plant and which are similar in ch:u.acter and closely related to the bast fibers of the preceding clars. This class includes Manila hemp, Sunn hemp, Slsal hem and related fibers. Fourth, we have the woody fiber oftrees which consists of the various elements of which tbe fibrovascular tissue of the wood is composed.
A classification in accordance with the industrial uses of cellulose may be simpler and more logical. Four groups come within such a classification: 1. Fibers used in the textile industry. 2. Paper-making fibers. 3. The purified celluloses which form the raw materials for the preparation of the cellulose derivatives. 4. A miscellaneous group consisting of the fibcrs used in corda e, as stuffing materials for upholstering, ria brush and mat €item, and for a number of minor uses.
A fifth class might be added-the cellulosic materials of the lumber industry-but these will not be discussed in this paper except in their bearing as sources of cellulose. TEXTILE FIBERS
COTTON. The purest form of cellulose which occurs in mature is cotton, which contains more than 95 per cent of cellulose. It consists of the unicellular hairs which are attached to the seed of the cotton plant. It is indigenous to nearly all subtropical countries but appears to be best capable of cultivation in warm humid climates where the soil is .sandy. The principal centers of cultivation are the southern part of the United States, India, and Egypt. Cotton is also raised in various other parts of the world-notably China,
Russia, South America, the east and west coasts of Africa, and the West India Islands- but these sections are relatively unimportant as compared with the United States, India, and Egypt, which together produce approximately 85 per cent of the world’s cotton crop. New and large areas in Russia recently opened up for cotton cultivation may make that country an important factor in the world market. The cotton belt of the South, embracing the thirteen states situated in the coastal plain extending from Virginia and North Carolina to Texas, is the most important cotton-producing center in the world. The area devoted to the raising of cotton in this cotton belt is approximately 45,000,000 acres, or over 98 per cent of the total United States cotton acreage. The 1930 cotton crop from this section amounted to 13,700,000 bales or 6,863,000,000pounds. Slightly over half of this amount is exported, the balance being consumed in the United States. The manufacture of cotton textiles in the United States is centered in two areas-the northeastern section (around New England) and the South. While Beverly, Mass., is credited with the distinction of building the first cotton mill in the United States in 1787, historical records show that during the same year a mill was erected near Charleston, S. C. At any rate, the South began the manufacture of cotton goods at a very early date. It was discouraged, however, by many of the leading citizens of the South. Thomas Jefferson was opposed to it, believing that the people would be happier and more virtuous and prosperous in the pursuit of agriculture than they could be with the vices and evils of manufacturing towns in their midst. The tariff laws a t that time intensified the opposition to this branch of industry, and John Randolph in a speech in the House of Representatives in 1824 declared that if there were no other obstacles, the climate was against it. Notwithstanding this early opposition, the industry grew gradually until toward the end of the nineteenth century, when spindles and looms began to appear in greater numbers in the South. Up to about 1913, the industry grew in the North and South a t about the same rate, but since that time the South has forged ahead of the northern section, so that in 1930 the South produced 67 per cent of all the domestic cotton goods manufactured, and consumed 73 per cent of all the cotton used in American mills and 20 per cent of the entire world’s cotton consumption. The length and the character of the cotton fiber or staple are the most important factors that determine the value of cotton. Commercially, cotton is divided into two classes: short staple of 11/18 inches and under in length; and long-staple cotton of 11/8 inches and over in length of fiber. The length and strength of fiber produced in any locality depends on the variety planted, the soil, climatic conditions, and cultural methods. The processes through which the raw cotton passes are entirely mechanical. The lint or fiber is separated from the seed in the cotton gin, after which the cotton is baled and
