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'United States Patented May 6, 1924. - 1,492,921} ‘UNITED STATES PpATENTy OFFICE. HAROLD P. KNIGHT,‘ OF BOROSOLVAY}, THOMAS M. CRAMER, 0F OAKLAND, AND GEORGE A. OONNELL, OF‘ALAMEDA, CALIFORNIA, ASSIGNORS 'ro .racr'rrc COAST BORAX CQM'PANY, A CORPORATION OF _ PROCESS or Pnonucme SODIUM‘ commas. No Drawing. Applit ?on ?led May 25, 1922. serial'li'o. 563,669. To all whom it may concern .' . _ VWe make use of this reaction to obtain Be it known that vwe, HAROLD P. KNIGHT, liquors and natural brines more concentrat of Borosolvay, San Bernardino County, edwith respect to B203, through the con THOMAS M. CRAMER, of Oakland, Alameda version of the less soluble tetraborate to the 5 County, and GEORGE A. OoNNnLL, of Ala: more soluble metaborate. This can be made meda, Alameda County, all in theState of to take place, for example, in solar ponds California, and all citizens of the United Where evaporation is effected at the natural States, have invented a certain new and use temperatures prevailing, as at Owens Lake ful Process of Producing Sodium Borates, of and Searles Lake in Caifornia. 10 which the following. is a specification, With, a solution containing the compm 60 The invention relates to a- process of pro nents of the reaction represented above, we ducing sodium borates such as" sodium tetra? have found that the addition of carbon di- - borate or borax. _ '_ . o _ oxide under certain conditions willresult in An object of the invention is to provide 'the conversion of monoborate present in so 715 a process of obtaining sodium borate from lution to borax, and some of this borax will ‘ liquors obtained from the decomposition of react with, the s6dium carbonate present to borate ores or salines containing borax or form sodium sesquicarbonate. An equi metaborate. ’ ' librium is established that results in the for Another object of the invention is to pro mation and crystallization of borax and so 20 vide a process of obtaining sodium borate dium sesquicarbonate together. We have 70 from such-liquors without the use of the ma found that this crystallization occurs favor terials now customarily 'used, such as tron-a, ably under temperature conditions ranging ' sodium bicarbonate or carbon dioxide. 'from 25° C. to 40° (3., but we do notdesire to The invention possesses other advanta limitjourselves to such‘ temperature, range geous features, some of which, with the fore since the mixture maybe crystallized out 75 going, will be set forth at length in the fol at other temperatures. When it is desirable lowing description ,where we shall outline to increase the yield of 'the mixture of crys in full, the process of our invention and one tals, the temperature of the carbonated solu» method of carrying it into effect.‘ 1 _ tion may ber'educed. When a solution is ob- ' We have found that borax (Na2B,O,) tained wherein both the sodium tetraborate so will react with sodium carbonate (Na2CO3), vand sodium sesquicarbonate are saturated at in aqueous solution, to form sesquicarbonate a given temperature and the solution is of soda (NazC‘Os-NaHCOs) and sodium maintained, at that ‘temperature, the further metaborate (NaBOZ) in accordance with addition of carbon dioxide will result in the the following reversible reaction :—' crystallization of a mixture of sodium tetra borate-and sodium sesquicarbonate in ap proximately the molecular proportions given in the above reaction, that is, 202 parts an- ' The molecular-proportions of this reac hydrous sodium tetraborate and 380 parts 40 tion are as follows :-— ‘ _ anhydrous sodium sesquicarbonate. ; 00 Such solutions are obtainable from natural 424+202+1s:380+264." saline lakes such as Searles Lake and Owens ‘We have found that this reaction takes place Lake in California. The liquors from these under a wide variety of conditions and that lakes aresaturated or approximately satu 45 the presence in the solution of certain ‘neu rated with‘ sodium sesquicarbonate. When 95 tral salts, such as sodium chloride, aids in the solution or the lake brine is too dilute, the progress of the reaction by rendering the that is, when too much water is present- to - sodium sesquicarbonate less soluble and permit the crystallizing out of the sodium v thereby causing it to crystallize out of solu-. tetra-borate and sodium sesquicarbonate upon 50 tion. ' the maximum carbon dioxide addition, the 100 ‘1,492,921 solution or brine is preferably evaporated to metaborate is converted into the tetraborate saturation with sodium sesquicarbonate and in accordance with thefollowing reaction.’ ‘ approximate saturation with B20‘8 ‘in the form of borax andv monoborate. The car 50 bon dioxide gas should not be introduced into the solution at a greater rate than. the _' The vtetraborate is recovered from the re rate of crystallization of the sesquicar sultant solution by cooling, whereupon the bonate, since a more rapid introduction of tetra‘borate crystallizes ou't and-is readily re the carbon dioxide may result in converting. coverable. ‘ - ' ' ' ' 55 10 the sesquicarbonate to the bicarbonate. ' The ' Throughout‘ the vspeci?cation, we have - ' carbon dioxide reacts' both with the sodium used the formulae of the anhydrous salts, carbonate and’ the sodium -metaborate_ to for‘ the purpose of convenience, but it is to form sodium sesquicarbonate and sodium ‘be understood that water of crystallization tetraborate accordance with the following is. always present; 60 15 reactions: , ' ' I - ' ' .-We claiinz- : * '. 1. The method ‘ofproducing sodium tetra- ' borate from a mixture of sodium tetraborate -3Na2CO,+,CO2_-l-H2O:' Y ‘ 2(Na’ZCOI'NaHCO3),: - . - and sodium sesquicarbonate which, comprises bringing together the v sodium tetraborate 65 20 The sesquicarbonate and the tetraborate' and sodium sesquicarbonate and sodium met crystallize- on together, forming a‘ mixture aborate in a hot aqueous solution whereby. "of the two sa ts in approximately molecular the metaborate is converted into tetraborate. proportions. 4' _ ' and the sesquic-arbonate is converted-into _ Mixtures of varying proportions of bicar_ sodium carbonate and cooling the solution 510 25 bonate, trona and borax have been hereto vto'cr'ystallize outtetraborate. -. fore produced, but, to our knowledge, had - 2. The method of producing'sodium tetra no commercial value. We have found that ‘borate from a mixture of sodium tetraborat'e such mixtures,‘ as well as our mixture. of and sodium sesquica'rbonate in substantially sesquicarbonate and ‘borax in approximately _molecular ‘proportions ’ which } comprises 75 30 molecular proportions, may be advantage bringin together‘ the sodium tetraborate ously employed in thecommercial manufac and sodium sesquicarbonate and sodiuin‘met ture of sodium borates, such as borax. aborate in a hot aqueous solution whereby In the manufacture of borax, from liquors the metaborate is converted into tetraborate _ - containing sodium metaborate, such for in and the sesquicarbonate into sodium carbon~ 80 35 stance as are 'obtained from the decomposié ate and cooling ‘the solution to crystallize tion ofborate ores or from saline liquors, it out tetraboratej has been customary to convertthe metar In witness whereof we haveh'ereunto set I borate to tetraborate, by treating the liquor, our hands,» the said _HA_ROLD P. 1(NIG , at While hot, with trona, sodium bicarbonate Borosolvay, California, 1 this 11th da of 85 40 or carbon dioxide. We have found that this May, 1922; and the said THOMAS M. CRAMER conversion may be accomplished by the use and GEORGE A. CONNELL, at San Francisco, _ of the above mixture of sodium sesquicar California, this 8thv day of May, 1922. bonate and sodium tetra'borate. In accord ' ance with our invention we mix the mixture HARO'L-DP. KNIGHT. 45 of crystals, or an aqueous‘ solution thereof, - THOMAS M. CRAMER. with the said liquor while hot, whereby the GEORGE A, CONNELLJ .
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