EXTRACTION of POTASSIUM CARBONATE from WYOMINGITE %nlcy
J. Green and Chrrles E. McCarthy
U. S. WREAU OF MIMES, COLLEOE PARK,
MD.
Kinetics of Base-Exchange Reaction b b b In conjunction with the d y of a proce# for the production d pearl ash and soda ash hom Wyomingite rr.d trona, the kinetics d the brrn-exchange n r d i o n between wyomingik and sodium urbonrtc have h e n investigated both in 1- and in 1 0 y d o n rutochves. The effect of concentration of reactrnb, time, and temperature on the rate of extraction of p o t d u r n from wyomingite i s determined, and an equation nlrting thm variables i s derived. The range of temperature, rrtio of sodium urbonrtc to Wyomingite, and time are, rrcprctively, 185*toP10°C., 0.303 to 0.550, 0 to 5 houn. Microscopic examination of the Wyomingite before md rher reaction shorn that the only potmiurn-bearing m i n d rttrcked is leucite, an indication that the Lemberg reaction i s the only one occurring. A t conrtrnt temperrture the relation between exbaction d potrssium oxide, time, and initial rrtio of sodium crbonate to Wyomingite un be expressed by the equation:
log1
- (Z/C.)
=act
HE wyomingite deposits of the Leucite Hib of Wyoming are an immense potential source of potsah. Estimates by Schultz and Crow ( 4 ) indicate a deposit of a t least a billion tons. A number of attempts have been made to extract the potash from this mineral, but to date none has pmved feasible (6). In 1933 Pike described experiments in which a base exrhange was effected by means of Green River brine and a sodium chloride solution (3). Recently, however, a large d e p i t of practically pure trona was discovered about 18 miles west of Green River, Wyo. (6). The fortuitous proximity of the two d e w i t s suggested a process whreby the rrona could be calcined (tu crude soda arb), dissolved in water, and reacted with the wyomingite to produce a solution o f potassium and sodium carbonates. By auitable treatment ( 1 ) this solution would yield refined potsssium and Bodium cartm na tes. 111 1876 Ikniberg first showed that the mineral leucite w8~1converted to analcite by autoclaving with sodium chloride solution af 18o0 7 0 195" c. for 18 hours (2). He dso found that potrrsriiiini carbonate solution reacted with the analcite quantitatively ant1 restored the leucite, an indication of the reversibility of the reaction. The equation for this baseexchange reaction is:
T
i
with Sodium Carbonate The mineral coniposition of Wyomingite ici 50% leucite, 15% phlogopite, 12% diopside, 15% kataphorite, and 8% glass and apatite, the potash-bearing minerals being leucite and phlogopite (3). Microscopic examination of the Wyomingite before and after renctioii ahowed that only leucite was altered, an indicatinn that the potash is extracted only from the leucite. METHODS.The experimental extractions were carried out both in a 1-gallon laboratory autoclave and a 100-gallon pilotplant autoclnve. The operetirig conditions are presented in Table 11. For each ciondition of initial sodium carbonate:wyomingite rrrtici and temperature, the reaction time at the selected ternperature was varied from 0 to 5 hours. The filtered solutions were analyzed for sodium carbonate potassium carbonate, sulfate (SO1), and silica, and occasionally for other impurities. The extractions per 100 pounds of Wyomingite were then determined by the following calculations: 1. The ratios of sodium carbonate, sulfate, and silica to potassium carbonate. 2. The potassium oxide extraction per 100 pounds of wyominkto by usc of the equation:
-
The derivation of this equation is bawd on the assumption that there is a stoichiometric base exchange between potassium carbonate and sodium carbonate, the wodium oxide replacing thc po-ium oxide in Wyomingite, mole for mole. The uw of this equation eliminated the need for closely controlling the water losag, particukrrly in the pilot-phnt filtering step, in ordrr to rmke yield calculationa, since roncentrations do not onter into the equation. Tht*validity of this method way periodicatly ('OII-
Table 1.
+ 2K
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