Stump Puller Extracting Stump from Earthy Matrix; Circle Shows Nutcracker T y p e of Extractor
1. W. Humphrey HERCULES POWDER COMPANY, WILMINGTON, DEL.
That modern sector of the industry known as wood naval stores was born a t the turn of this century, without benefit of much engineering or chemical technology. Today wood flows naval stores contribute more than one third of this country’s dead stump. The oleoresinousproducts of the pine can boast rosin and turpentine by processing stumps from the southern an ancient lineage extending back to those days when the pine belt. In addition, all of our pine oil is supplied by the Phoenician sailors of the first great comniercial nation wood naval stores industry, given by Mother Nature to man caulked tbeir rude ships with the pitch of the pine. Devas a bonus for his ingenuity in applying chemurgy to the cutotees of the pine tree assert that Noah “pitched his ark over pine lands. within and without” by means of pine pitch, but it must be During the first decade of this century, the experts propheadmitted that this ancient mariner may have used a natural sied that the gum naval stores industry would wither and asphalt. A report submitted to Sir Walter b l e i g h over shrivel because of the gradual depletion of the virgin pine three and a half centuries ago stressed the value of the great forests. But this calamity was averted by the self-seeding pine forests of the Carolinas (68). Our first commercial of the rapidly growing slash pine in the cut-over pine lands, shipment of industrial products carried naval stores comits well as by improved methods for procuring gum oleoresin. prising tar, pitch, rosin, and turpentine from the Virginia In the meantime, adventurous spirits hastened to forestall shores in 1608. the threatened shortage by processing some of the milIions The name “naval stores”, however, arose from the highly of pine stumps in the southland. Ventures that were able valued use of pine tar and pitch for caulking leaky ships and only to steam the milled wood for turpentine and pine oil preserving their rigging. Today this use has almost vanished, proved economically unsound. Subsequent solvent exyet the primary oleoresinous products of the pine treetraction of the wood to recover its approximately 20 per cent rosin and turpentine-are still called “naval stores”; the rosin content was also necessary. term usually includes some of its other products such as pine The first successful commercialoperation (66,68),known as oil, pine tar, and pitch, or more loosely covers the multitude the steam and solvent process, was pioneered by Homer T. of resinous and terpene derivatives procured by tapping or Yaryan a t Cadillac, Mich., in 1909. His plant a t Gulfport, extracting the pine tree. 1062 all of the rosin given by the pine tree is ESSENTLALLY classified either as gum or wood rosin; the former from the living tree, the latter is extracted from its
oatober, 1943
INDUSTRIAL A N D E N G I N E E R I N G C H E M I S T R Y
Mi.,produced 14,300round barrels of rosin in the 1910-11 season,along with considerable turpentine and pine oil. Another plant, still in operation, was soon opened, so that mood rosin totaled almost 100,000 barrels in the 1912-13 season, representing about 4 per cent of the total rosin production. The wood naval stores industry throughout much of the decade and a half following its inception was placed in a precarious position on account of certain defects in the quality of the products of those days, by inadequate development of processing methods, as well as by occasional drastic price declines. Accordingly, competition with the long established gum industry was feeble. But today about half of our rosin is produced by wood naval stores plants. Refined wood rosin now competes SucceaSfuIIy with gum rosin in a wide range of applications. GUM ROSIN PROCESINO
There is a sharp contrast between the simpIicity of harvesting gum rosin and the complexity of procuring refined wood .osin. Gum rosin is produced a t approximately B thousand small stills throughout the pine belt which extends over a thousand miles along the south Atlantic and Gulf Coastal plains. Shallow, V-shaped incisions are cut on the pine tree, usually the long leaf or slash species. Additional hackings are made duringse vera1 gum-flowing seasons. The oleoresin or gum which oozes down the face of the tree is collected, then heated in a small copper still to drive off spirits of turpentine. The molten rosin is filtered and barreled, its color depending largely on the period over which the tree has been bled, as well as on the care exercised in collecting and processing its oleoresin. The small-scale gum rosin producer has been handicapped by lack of technical control. Modern technology, however, is now coming to his aid, chiefly in the form of large, central, modern processing units, fostered by federal agencies. WOOD ROSIN PROCESSING
The wood rosin producer carries on after the gum rosin farmer and lumberman have passed by, leaving their legacy
1063
contrast to the colorful art practised by the gum naval stores industry since colonial days. After the stump has remained in the ground ten years or so, its bark and sapwood have sloughed off, leaving the rosin concentrated in the rich heartwood. The pine stump analyzes approximately 18 per cent water, 5 per cent terpene oils, 22 per cent rosin, and about 4 per cent of a gasoliieinsoluble resin, leaving about 51 per cent of cellulosic- and ligneous-type materials (28). Methods of extracting the stump from its earthy matrix vary with the terrain. Dynamite is often used, as well as various forms of tractors and stump pullers (629. One type has a nutcracker which, dropping on the stump, firmly grips and pulls it from its footing along with its anchoring tap root, simulating a gigantic dental operation. After some splitting and trimming, the stumpwood, along with roots and any other rich resinous wood which happens to be available, is loaded on gondolas. It has been estimated that the wood naval stores industry is responsible for annually clkaring approximately 200,000 acres of cut-over pine lands, releasing them for agricultural use. When the harvested wood arrives a t the naval stores plant, it is either stored in the stock pile or conveyed directly to the mill rooms. There it is devoured by a mechanical hog provided with a rotary disk chipper, then shredded by hammer mills to splinter-type chips suitable for extraction. The extraction procedure has long been known as the steam and solvent process since both are employed in removing the volatile oils and rosin. The milled mood is placed in a series of vertical towers about 24 feet high, each holding about 13 tons of chips, After steaming for turpentine and part of the pine oil, the wood is countercurrently solvent-extracted by flooding with a petroleum naphtha cut. In a recent modification of the proces.s, the steaming step is omitted, the turpentine, pine oil, and rosin being extracted from the wood by a suitable volatile solvent. Solvent, turpentine, intermediate terpene cuts (chiefly dipentene, terpinene, and tarpinolene), and finally pine oil are fractionally separated, leaving as residue crude wood rosin. Around 12 gallons of volatile oils are obtained per ton of wood.
The gum rosin from the oleoresin of the living pine tree formerly was the only source of rosin. In recent years 40-50 per cent of our total rosin production has been obtained by extracting wood rosin from the stumps of the cut-over pine lands of the southern states. The refining of crude wood rosin sufficiently to render it competitive to gum rosin proved a difficult problem. Its com= mercial solution was first achieved by treatment with furfurd using a dual, immiscible solvent procedure. Furfural selectively extracts the dark resin fraction, leaving the refined rosin in the petroleum naphtha layer. Other types of solvents for rosin color bodies are discussed as well as the selective solvent refining of the rosin derivatives.
L of countless pine stumps. But wood oleoresin will not gush forth from the old pine stump merely by hacking its weatherbeaten face. Drastic and intricate operations are necessary to separate and refine its rosin. The cost of a large, modern, wood naval stores plant runs into millions of dollars, as cornpared to thousands for the usual small gum rosin plant. There are about twelve wood naval stores plants in this country. Production of wood naval stores is a science, in
WOOD ROSIN REflNlNG
When wood rosin was first produced about thirty-five years ago, it enjoyed only a limited market. The manufacturer could boast both of its uniformity and cleanliness as compared to the variable quality of the gum rosin produced by hundreds of farmers; but the single grade of wood rosin of that era had several defects when measured by the accepted standards for gum rosin.
INDUSTRIAL AND ENGINEERING CHEMISTRY
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Wood rosin possessed il little lower iiielting point and &J poorer solubility in petroleum ligrlroeari~anst,hm gum rosin. The wood msin plant >vas frequently infested by a n unknown species of "uemlin" rrliich ilelighte~lin mysteri. ously transforming the otlirrn-ise olt'iir :mil iiniforin urirefinrci d
wood rosin into :s snaarlike.
semicFystalIini
Vol. 35, No. 10
tritering rvetlge for the attack of drastic chemical reagents. Acr:orriinply, a physical rather than 5 chemical treatment w:m indiented. Prior to ihe era of chemical treatments directed toward the drcolorizing o i wood rosin, it m s found (19) that distillation of the darker erades of eum Y
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rosin under mass, una(:reduced preseeptable to any sure improved consu m e r . t h e i r color. Fortunately Investigation ' 'Chemlin showed that dtielicus" fell reduced presunder the spell sure distillaof chemical tion of wood technology and rosin by modiaccordingly fied proceceased crystald u r e (16, 47) lizing w o o d also yielded rosin. pale grades; The unforb u t some givable sin of of its latent unrefined wood or potential rosin, howver, color bodies wsa its characof a phenolic teristic, dark t y p e were red color, difcwried over, fering notably producing deep from the conyellow tobrown ventional c o l o r s when yellow t o the d i s t i l l a t e brown color was contacted g r a d e s of with a l k a l i . Figure 1. Lister Resin Refinins Tower orthodox sum fiactionaf disrosin. Furthert i l l a t i o n (89) more, color difor condenferences between gum rosin and t,Iw anpurified wood rosin of .;;ition (41, 66) were helpful but the last trace of these that day were magnified on contacting them with air and su~ii,-discoloring components stubbornly resisted eviction alkali. The wood rosin soap lapidly acquired ttn objectionfrom distilled wood rosin. Wood rosin still remained an outable, deep brown color with exterior discolor&tiun m n e ~ cast. lacking eye appeal, and unwelcomed by the soap, varforming in the suep bar. Rolstively little cbnge occurred nish, and much of the paper sizing industries. But today in gum rosin soap, and t.herefore wood rosin wis effectively the improved and desirable characteristics of refined wood barred from entering the swap, aster gum, and varnish fields rosin arc recognized throughout the rosin consuming in88 well as from much of the paper sieing business. Until dustries. properly bleached, it was doonred to remain in tlie lowerBy virtue of the irsolubility of nmny of the wood rosin priced rosin market, with outlets chiefly in linoleum, cure color bodies in petroleum fractions, they could be almost oil., and the darker sized grades of papers. eliininated on refrigeration of the rosin in butane solution Many were the attempts tu refine it to a pier grade before (88). Iioivever, the smdl fration which remained proved a process %.as finally developed which could be commersufficient to prohibit industrial usage of this type of refined cialized. Yaryan found that treatment with sulfuric acid wood rosin. ( 6 7 improved its color greatly, but the process could not be FURFURAL REFINING economically developed. Other chemical reagents, including amphoteric metallic chloride8 ( S I , 62), boric acid ( S ) , hexaThe two eoniniercially successful processes eventually methylenetetramine or formnldehyde (%), alkali (@), etc., developed for refining aoud rosin depend upon the physical effected considerable improvement, especially if followed by removal of color bodieseither by an adsorbent (67,69,64)such distillation under reduced presaun:. Yet tile lierformrrnw of ns fuller's earth or bv the selective solvent furfural. Comnone of these early refined types of wood rosin on testing in soaps aid rarnishes w1t8 such as to warrant, plant-scale production. The reactive nature of tlie rosin hcids is not auspicious to the removal of a substnntial proportion of assorted color bodies from wood rosin on a technical scale. The two unsaturated linkages and tertiary carboxyl group of the abietic and pimaric type rosin acids afford nn I
October, 1943
INDUSTRIAL AND ENGINEERING CHEMISTRY
106s
preferentially dissolves its TABLXI I, CHARACTERISTICS OF COMMERCIAL W O O D ROSINS AM) EXTRACTED RESINS color-bearing components and leaves the purified rosin in Sa oniUnRefracthe other liquid phase. Approx. fcasaponi- Meth- Gasoline- HerRing tive Lovibond Acid tion fiable, oxyl, Insol., oulea & Index Densit In some detail a solution Grade Color' No. No. % % % drop ball (ZOO C.) ( Z O O d) of wood rosin in a petroleum Wood Rosins naphtha cut is agitated with Crude. 80A-l- l9OR 150 170 8.5 1.7 25 86 74 1.56 1.10 a relatively small proportion ktehned Ii 40A 4-8R of furfural and then allowed 162 169 7.5 0.05 81 72-5 1.5470 1,069 I 40A + 4 . 6 R 163 171 7.5 0:io Trace 82 72-5 1.069 to separate into two layers. K 40A 4- 2 . 6 R 164 171 7.0 0.45 Trace 82 72-6 1:5463 1.069 M 40A 4- 0.75R 165 171 0.35 Trace 82 72-5 .. .. 1.067 7.0 The higher-specific-gravity h39A 165 172 6.0 0.30 Trace 83 73-8 1.067 WG 27A 166 172 furfural layer contains sub6.0 0.20 83 73-8 1:&b3 1.067 Xb 128 171 174 7.0 .. Trace 1.065 Nil 82 73-8 1.6450 stantially all of the colored Extracted Resins components of the rosin Priniary Too dark 90 150 8.0 5.6 95 114 102 1.58 1.21 along with a small proporSecondary Too dark 119 150 12.0 3.5 64 83 73 1.68 1.15 tion of its rosin acids. 4 = amber R red {'(e-inph standard ouhe). By reduced &xsure distillation of I grade. Evaporation of the furfural for recycling leaves a resin of dark color. From the gasoline phase is recovered the refined rosin, its improvement in color dqending, solubility of the crude rosin components by virtue of physicxl with certain limitations, upon the refining conditions imcharacteristics less conspicuous than that of color. posed (83, 48). Some degree of analogy exists between the furfural reThe essential step of effectively contacting rosin with fining of the polycyclic components of wood rosin and the furfural may be performed by one of several methods. Thus, separation of lubricating stocks into two fractions by means unrefined rosin, petroleum naphtha, and furfural may be of furfural. For simplicity, the latter system may be conheated sufficiently to form a single phase, separation into two sidered to include three major components: furfural, cyclic layers occurring on cooling to room temperature. Also, hydrocarbons paraffinic in character from bearing long chains, rosin-naphtha solution at room temperature may be washed and polycyclics having a few relatively short chains (81). once batchwise or countercurrently by several small portions The latter tend to dissolve preferentially in the furfural as the of furfural. Refrigeration may be included to separate reextract phase. fined rosin more completely from its color bodies. On the other hand, the crude wood rosin system comprises Wood rosin is purified commercially on a continuous scale four major components: furfural, petroleum naphtha, by washing with furfural in the Lister rosin refining tower hydroaromatic or unsaturated rosin acids, and the less (60),shown in Figure 1. This tower may be approximately acidic, more complex, naphtha-insoluble and furfural30 feet high and 6 inches in diameter, but in present plant soluble resin fraction which is more aromatic and more practice is about 40 feet high and 3 feet in diameter. It is highly oxygenated than the rosin acids. The naphthadivided into chambers A, perhaps 8 inches high, by means of soluble rosin acids generally carry an isopropyl group and plates B formed of fine mesh screening. Approximately 15 twp methyl side chains. It should be noted, however, per cent crude rosin in petroleum naphtha solution, C, which that the rosin acids are also furfural soluble. may pass through a cooler, D, moves up the tower through the screens as it is washed by the descending furfural, F , collected in pools. The latter are retained on the screens TABLE 11. METALCONTENTOF COMMJJRCIAL WOODROSINS and overflow into the tops of the downpipes, E, provided AND EXTRACTED REaINS with side outlets G near the bottom. Refined rosin solution Metal Content, P. P. M. H is drawn off from the top of the tower and spent furfural Grade Fe AI cu Mn solution I from the bottom. Refined Rosins Prior to the foregoing treatment, the rosin solution is H 1 2
