United States Patent to 11 4,018,876 Jordan 45 Apr. 19, 1977

54) PROCESS FOR THE PRODUCTION OF METAL AND SODA ASH OTHER PUBLICATIONS 76 Inventor: Robert Kenneth Jordan, The Carlton Alien Property Custodian (APC) 227107, Suzuki, H., House, Suite 1431, 550 Grant St., filed Aug. 27, 1938, published Apr. 20, 1943. Pittsburgh, Pa. 15219 Primary Examiner-O. R. Vertiz 22 Filed: Mar. 4, 1975 Assistant Examiner-Gary P. Straub 21 ) Appl. No.: 555,189 57 ABSTRACT 52) U.S. C...... is a se a s & 8 was a 423.1421; 260/.538 A process for the simultaneous production of relatively 51 Int. Cl...... C07C 55/06; C01B 3 1/24 insoluble metal oxalates and carbonates and bicarbon (58) Field of Search ...... 260/538,527 R, 526 R; ates of alkali metals and ammonium in which a metal 423.1419-422,430 carbonate and an ammonium or alkali metal 56) References Cited are combined in water or methanol, optionally with the UNITED STATES PATENTS addition of . l,687,480 0/1928 Buchanan et al...... 260/.538 2,002,342 5/1935 Enderli ...... 260/.538 3 Claims, No Drawings 4,018,876 1. 2 Even considerable ferrous carbonate is available, but PROCESS FOR THE PRODUCTION OF METAL as iron ore, FeO is very cheap, there is no interest in OXALATES AND SODA ASH it. But other valuable carbonate ores or metal carbon ate intermediates could be available if there were and This invention relates to a process for the simulta 5 inexpensive direct way to process them to useful inter neous production of metal oxalates and ammonium or mediates. As noted above, nickel, copper, zinc and alkali metal carbonates from metal carbonates and other metals are found in nature as natural carbonates, ammonium or alkali metal oxalates. or in their processing could be economically extracted The carbonates of many metals exist in great abun as their carbonates. dance in nature, examples include soda ash, limestone, 10 In a number of copending applications I disclose a dolomite, siderite, rodochrosite, smithsonite, azurite, series of processes which among other things promises spherocobaltite, cerussite, Zaratite and magnesite to to make oxalates, especially sodium oxalate, most eco name a few. Soda ash is usually found in the mineral nomically, essentially from common salt and carbon trona, but large deposites are located far from the mar monoxide. As is potentially available ketplace. And although much trona is chemically pro 15 in great quantities at low cost from blast furnaces and cessed to produce both soda ash and bicarbonate of as salt is already very cheap, low cost oxalates could soda, high rail transportation costs in the United States provide the basis for a new kind of chemical venture. have made these chemicals relatively expensive for the As sodium oxalate is made now, caustic soda is car glass and detergent industries that are respectively their bonylated with carbon monoxide to yield a solution of major consumers. 20 sodium formate which is evaporated to dryness, care The major uses for limestone in the chemical industry fully melted at about 263 C and then rapidly heated to generally require that it first be calcined to lime. For about 400° C for 5 to 10 minutes causing fusion to example in the Solvay soda ash process, ammoniated sodium oxalate with the evolution of hydrogen. The brine is carbonated to precipitate out bicarbonate of sodium oxalate is quenched by dumping it in water. soda, leaving a solution comprised essentially of ammo 25 Treatment of the solution or slurry with hydrated lime nium chloride and which necessarily must be treated causes the precipitation of and yields a with hydrated lime to recover the expensive ammonia. solution of sodium hydroxide which is some-concen In the past when all forms of energy were cheap, the trated before recycling in the process. Calcium oxalate cost of lime was a minor factor in the overall cost of is treated with a large excess of dilute sulfuric acid at 30 about 70° C to first precipitate calcium sulfate, and Solvay, soda ash, but this is no longer true. Another then on cooling the dihydrate of crystallizes factor in the Solvay process is the disposal of huge out. Again the liquor is recycled. Clearly, as sodium quantities of calcium chloride solution which has re oxalate by my processes can be made from salt and sulted in closing a number of soda ash facilities. carbon monoxide, the causticization of sodium oxalate Soda ash and bicarbonate of soda can be made by the 35 to yield caustic soda is tantamount to a method for the carbonation of caustic soda, which is how practically nonelectrolytic production of caustic soda. Also, it is all potassium carbonate and bicarbonate is made. But obvious that by carbonation the caustic soda, sodium potassium hydroxide and sodium hydroxide are pro carbonate and sodium bicarbonate can be made. But duced by the electrolysis of the corresponding chloride, again, the caustizing with lime is expensive if it is de an energy intensive and not inexpensive process. While 40 sired to make sodium carbonates. Heretofore however, the processing of trona has supplanted the closed down these steps were well known and would have been synthetic soda ash production, the cost to the glass necessary in the production of sodium or potassium industry has risen mostly because of rail transportation. carbonates via oxalate chemistry. . . " Potassium carbonate has a number of uses, the fastest Metal oxalates have a wide range of very useful prop growing use appears to be in the removal of carbon 45 erties. Nickel, copper and a number of other metal dioxide and sulfur containing compounds from natural oxides decompose to the metals at only 300-400 C. gas and chemical process gas streams. Likewise, iron and cobalt oxalates in an atmosphere of Limestone and dolomite are plentiful in most parts of hydrogen decompose to the metals at only slightly the United States and the world, but again chemical higher temperatures, like 450° C and other metal oxa utility necessitates that they be calcined, a process 50 lates behave similarly. For example, manganous oxa requiring an average of more than 5 million btus per late decomposes in hydrogen or nitrogen to yield ton of lime or dolime. As dolomite and magnesite are mainly the lower oxide, but as the product is very oxy excellent sources of ion, for examples for gen sensitive, some manganese metal may be present. magnesia and magnesium metal, low cost ways to pro Mixtures of metal oxalates are often easily separated, duce magnesium compound intermediates which avoid 55 for example magnesium and calcium oxalates can be calcination are needed. Manganese carbonate, rodo treated with caustic soda in which magnesium oxalate chrosite, is available throughout much of the world, but is relatively soluble. Manganese carbonate as found is not the preferred manganese ore in spite of the fact naturally is usually contaminated with iron oxide, that in the form of the carbonate, manganese has a FeOs, but manganous oxalate is essentially insoluble valence of 2 compared to 3 and 4 for the oxide ores. 60 while ferric oxalate is very soluble. Fortuitously a great The problem is that the carbonate ion is bulky and amount of oxalate chemistry is well known, so that if represents no value when shipped, only a cost. But new processes for their production are developed, again, calcination to remove the carbon dioxide is ex practical uses are instantly available. Therefore, it is an pensive so that in spite of its wide availability, manga object of my invention to provide a new and improved nese carbonate is not widely used as a starting material 65 process for the production of sodium and potassium for manganese dioxide, manganese metal or ferroman carbonates and bicarbonates. ganese. Again a process is needed to directly convert It is another object to provide a new and improved manganese carbonate into useful intermediates. process for the production of insoluble metal oxalates. 4,018,876 3 4 It is a further object to provide a new and improved chunks of some of the metal carbonates, especially process for the production of calcium oxalate. dolomite. 8 My invention is a process for the production of insol While water is the preferred media of the process, it uble metal oxalates and alkali metal and ammonium does proceed almost equally well in mixtures of water carbonates wherein a metal carbonate and an alkali 5 with methanol and acetone. In fact the process can be metal or ammonium oxalate are combined in water or conducted in methanol, but more sluggishly. In what methanol, or mixtures thereof, optionally with the addi ever media, by adding the metal carbonate and alkali tion of carbon dioxide at a temperature in the range of oxalate and optionally carbon dioxide continuously, from about -30 to about 300° C. the process can be made to be continuous. I have unexpectedly discovered that the addition of 10 Ideally the process conducted using water or metha finely divided limestone to a solution of sodium oxalate mol as the media is conducted at roughly 50°C at atmo causes an immediate and rapid rise in pH to about 11, spheric pressure or using carbon dioxide bubbled into where the process appears to cease. Thus when equi the liquid at only that pressure required. However, for molar quantities of limestone and sodium oxalate are forms of carbonates which do not react rapidly, it may mixed in water at about 50 a conversion of somewhat 15 be desireable or necessary to conduct the process at over 40 percent is realized and a measurable increase temperatures well above 100 C necessitating pressures in temperature is noted. As the pH approaches 11, the up to 20 atmospheres. This is especially true using process comes to a halt, but if carbon dioxide is bub natural minerals which contain silicates and sulfides in bled in, presumably lowering the pH by converting the addition to carbonates. sodium carbonate to sodium bicarbonate, the conver 20 A number of the oxalates prepared by the process are sion can be increased to almost completion. Clearly simply means for obtaining other compounds. Thus this offers a remarkable route to soda ash and bicar limestone is very cheap and leads to calcium oxalate bonate of soda if sodium oxalate can be produced and sodium carbonates when reacted with sodium oxa cheaply, obviating the necessity to make lime. As po late in water. But thermal decomposition of calcium tassium oxalate is also easily made by fusion of its for 25 oxalate yields calcium carbonate and represents an mate, it was tried under similar conditions and found to expensive route to limestone. As noted earlier, calcium behave likewise. While is not readily oxalate is commercially treated with dilute sulfuric acid made like sodium oxalate, it was also used with like to produce oxalic acid. In copending application results with calcium carbonate. Ammonium oxalate 551,151 filed Mar. 4, 1975, I disclose a process for the 30 production of ammonium oxalate from calcium oxalate also works. and ammonium carbonate. Similarly, British Pat. No. A series of experiments were then conducted to de 517,455 describes the conversion of calcium oxalate to termine the versatility of the process with a large num copper ammonium complex solutions and precipitated ber of metal carbonates. It was found that the carbon calcium carbonate through the use of a copper salt and ate of any metal having an insoluble oxalate operates in 35 ammonium carbonate. the process. behaves almost French Pat. No. 893,255 discloses the earlier noted exactly like limestone and the same can be said for separation of mixed magnesium-calcium oxalates ob dolomite. The conversions obtained initially with other tained using dolomite. Magnesium oxalate can be ther carbonates vary, but on addition of carbon dioxide the mally decomposed to , or can be used process can be made to go to essential completion. as an intermediate to magnesium compounds, for ex Thus CuCO, malachite, rodochrosite, thorium car ample magnesium sulfate. As noted earlier, a number bonate, nickel carbonate, siderite, spherocobaltite, of oxalates decompose in nitrogen or hydrogen at very AgCO, cerussite, witherite and smithsonite tested low temperatures to metals, including cobalt, copper, successfully. The only criteria is that the resulting oxa iron, nickel, silver and others. Manganese oxalate is late be relatively insoluble, even though the alkali 45 useful in preparing ferrites by thermal decomposition metal and ammonium complexes may have consider with mixtures of other oxalates such as iron and zinc able . oxalates. But manganous oxalate is an excellent source The process is essentially independent of the relative of divalent manganese for the production of manganese concentrations within reasonable limits, but particle sulfate which is electrolyzed to metallic manganese. size greatly affects the rate. While in time small chunks so Thus the process of the present invention not only of calcite can be digested in an excess of sodium oxa provides a means for refining carbonates but also yields late, rapid rates are obtained using powdered carbon valuable intermediates. ates, i.e., less than 200 mesh though reasonable rates The value of the alkali metal carbonates is well can had with 100 mesh calcite. known. As noted herein, ammonium carbonate can be The process can be operated over a wide range of 55 a valuable intermediate in the reverse process. Usually temperatures, especially when using finely divided the best means for recovering the carbonates from the metal carbonates. But there is a problem at lower tem solutions obtained in the present invention is simply to peratures when it is desired to obtain high conversions cool with further carbonation, precipitating the bicar in that the alkali carbonate concentration causes the bonate which normally has a lower solubility than the pH to rise rapidly, thus in effect stopping the process. 60 carbonate, lithium carbonate the exception. But isola On adding carbon dioxide the pH drops, but as the tion by evaporation is a reasonable way to recover the alkali metal bicarbonate is relatively insoluble, its pre potassium carbonates since both the bicarbonate and cipitation makes it necessary to conduct a second sepa carbonate are fairly soluble. ration of the precipitated products. But often this can According to the provision of the patent statutes. I be solved by simply heating. To achieve high conver- 65 have explained the principle of my invention and have sions at elevated temperatures is is desirable to main illustrated and described what I now consider to repre tain the system under pressure of carbon dioxide. Rates sent its best embodiment. However, I desire to have it are very high at elevated temperatures, even with understood that within the scope of the appended 4,018,876 5 6 claims, the invention may be practiced otherwise than the range of -30°C to 300° C under conditions suffi cient to maintain said liquid media in the liquid state to as specifically illustrated and described. produce alkali metal carbonate and metal oxalate. I claim: 2. A method according to claim 1 wherein the pH of 1. A process for the production of alkali metal car the reaction is maintained below about 11 by the addi bonates and metal oxalates wherein the metal is other tion of carbon dioxide. than an alkali metal, which comprises reacting an alkali 3. The process of claim 1 where said metal carbonate metal oxalate with a metal carbonate in a liquid media is calcium carbonate and said alkali metal oxalate is Selected from water, methanol, water-methanol mix sodium oxalate. ck ck ck ck tures and water acetone mixtures, at a temperature in 10

15

20

25

30

35

40

45

SO

55

60

65