United States Patent (19) 11) 4,336,236 Kolakowski et al. 45) Jun. 22, 1982 (54) DOUBLE PRECIPITATION REACTION FOR (56) References Cited THE FORMATION OF HIGH PURTY BASIC LEAD CARBONATE AND HIGH PURITY U.S. PATENT DOCUMENTS NORMAL LEAD CARBONATE 70,990 1 1/1867 Gattman .............................. 423/435 4,269,811 5/1981 Striffler, Jr. et al. ................. 423/92 (75) Inventors: Michael A. Kolakowski, Milltown, N.J.; John J. Valachovic, Fremont, Primary Examiner-Earl C. Thomas Calif. Attorney, Agent, or Firm-Gary M. Nath (73) Assignee: NL Industries, Inc., New York, N.Y. 57 ABSTRACT A process is provided for the preparation of high purity 21) Appl. No.: 247,441 basic lead carbonate and high purity normal lead car 22 Filed: Mar. 25, 1981 bonate by a double precipitation reaction employing a single lead acetate feed solution. The process is particu (51) Int. Cl............................................... C01G 21/14 larly applicable to processes for producing lead monox 52) U.S. Cl. ...................................... 423/435; 423/92; ide from solid lead sulfate-bearing materials such as 423/619 battery mud. 58 Field of Search ................... 423/92, 93, 435, 436, 423/619 17 Claims, 1 Drawing Figure AA/7AAY AW/A I 35 9 2 AAAAMAAJ AAAAW/ 4 3 A40/4 SI/AM (AMA) AAW (AAAA/70 SAAAAA % SAA/AAAAAY 32 20 7 2 23 26 AAAA All S01/0SAAAAW/ / Z/l/l) (02 (AAA04//0/APAA/AIAJ70 (AAS/A IAA (A60/AF S0Z/0/A/10/0 SAPA/PA/70 3. (AAA.0/7.0/A/AWA70 (AOPA AAA (AAA0AA 501/0/A/40/0 SAAAA/ 28 (AZA/MAIAW 29 30 4,336,236 1. 2 Othmer Encyclopedia of Chemical Technology, Volume DOUBLE PRECIPITATION REACTION FOR THE 10, pp. 614-616 (1953). FORMATION OF HIGH PURITY BASIC LEAD Various processes for the preparation of white lead CARBONATE AND HIGH PURTY NORMAL are described, e.g., in U.S. Pat, Nos. 428,017, 720,670, LEAD CARBONATE 1,349,334, 1,587,623, 1,720,196, 1916,302, 4,118,219, Great Britain patent specification Nos. 226,689, 495,051 BACKGROUND OF THE INVENTION and the like. This invention deals with the preparation of high Similarly, normal lead carbonate has been produced purity basic lead carbonate and high purity normal lead by a number of processes. See, e.g., U.S. Pat. Nos. carbonate in a single, multi-step process. The process 10 1,587,623, 1916,302, 3,883,348 and the like. involves a double precipitation reaction whereby the Certain of these processes are known to generally desired lead carbonate compounds are obtained from a disclose the production of either basic or normal lead lead acetate solution. carbonate. See, e.g., U.S. Pat. Nos. 1,587,623 and In the past, basic lead carbonate has been produced 1,916,302. However, such processes result in the precip by a number of processes. In one process, commonly 15 itation of an admixture of basic and normal lead carbon known as the Dutch process, metallic lead is cast in ate and are thus not suitable for the production of both small perforated plates or buckles, which are placed in a high purity basic lead carbonate product and a high earthenware pots over a weak solution of acetic acid. purity normal lead carbonate product. The pots are stacked in layers in tanbark, each tier being The ability to produce a high purity basic lead car supported by wood boards. The tiers are built up to as 20 bonate product and a high purity normal lead carbonate many as ten layers and the whole stack is then boarded product in a single process and from the same starting up. Fermentation of the tanbark generates considerable heat and carbon dioxide. The heat volatilizes the acetic material would be highly desirable from a commercial acid, causing it to react with the lead to form the lead standpoint. Basic lead carbonate is capable of use as a acetate, which, in turn, is carbonated by the carbon 25 pigment or as a heat stabilizer for flexible polyvinyl dioxide to form the basic lead carbonate. After 100 to chloride manufacture. Normal lead carbonate is useful 120 days, the stacks are dismantled and the white pow as a starting material for the formation of various other der is removed and ground in water, forming a water lead compounds. The ability to obtain both these com pulp. The water pulp may be filtered and dried to pro pounds in commercially useful form by a single process duce a dry basic lead carbonate powder, or it may be 30 would also provide the opportunity for savings in converted to a basic lead carbonate/oil paste by the equipment expenditures. addition of linseed oil. Because of the great affinity of A single, multi-step process which produces high basic lead carbonate for linseed oil, the oil will displace purity basic and normal lead carbonate products would the water from the basic lead carbonate. The lead-in-oil have significant applicability in connection with the paste is finished by passing it over a roller mill. 35 preparation of pure lead monoxide from impure lead In a second process, generally known as the Carter sulfate bearing materials, particularly impure lead sul process, powdered lead is suspended in water in large fate bearing materials such as recycled battery mud. revolving wood cylinders, acetic acid is added, and One such process for the preparation of pure lead mon carbon dioxide is passed into the cylinder. The reaction oxide from recycled battery mud is described in U.S. is completed in 10 to 12 days. This process permits 40 patent application Ser. No. 126,625, entitled "Produc better control than the older Dutch process and the tion of Lead Monoxide from Lead Sulfate with Acetic finished product can be made with a wide range of Acid', and filed Mar. 3, 1980, by Eugene Striffler Jr., et physical properties. al, now U.S. Pat. No. 4,269,811, and is commonly as Another process, commonly referred to as the Euston signed to the assignee of the present application. In such process, starts with feathered or mossy lead made by 45 a process, pure lead monoxide is prepared in a multi running molten refined lead metal into water. The step process which comprises: feathered lead is then oxidized by air in a solution of (a) reacting a lead sulfate-bearing material with an normal lead acetate into which carbon dioxide...is intro ammonium carbonate solution to convert lead sul duced. The basic lead carbonate forms as a precipitate fate to lead carbonate; and the lead acetate solution is recovered by filtration 50 (b) decomposing the lead carbonate to form impure and re-used. lead monoxide; Yet another process is an electrolytic process, which (c) reacting the impure lead monoxide with acetic makes use of a concrete cell divided by a porous mem acid to form a lead acetate solution; brane. In one portion of the cell, a lead anode is sus (d) contacting the lead acetate solution with carbon pended in a solution of sodium acetate, and in the other 55 dioxide to produce insoluble lead carbonate; and portion of the cell an iron cathode is immersed in a basic (e) decomposing the lead carbonate to form substan sodium carbonate solution. The passage of the electric tially pure lead monoxide. current removes the lead from the anode as lead acetate, Any lead dioxide present in the lead bearing material which forms a precipitate of basic lead carbonate in the may also be decomposed along with lead carbonate in anolyte. 60 step (b) of the process to produce additional lead mon Another process, generally referred to as the Thomp oxide. Alternatively, such lead dioxide may be treated son-Stewart process, produces a basic lead carbonate of with acetic acid in step (c) together with a reducing high quality and very fine particle size. Finely divided agent to simultaneously decompose the lead dioxide and litharge, lead, or a mixture of both, is suspended as a form additional lead acetate. slurry in water. Acetic acid is added, the material is 65 The process may be conducted in a continuous man aerated, and carbon dioxide is passed through. White ner. In the continuous mode, the by-products of reac lead of high basicity and fine particle size is produced in tions occurring in the process are used to form the rea the process. See, e.g., U.S. Pat. No. 2,218,940 and Kirk gents used in the various steps of the process. More 4,336,236 3 4. particularly, carbon dioxide formed as a by-product of normal lead carbonate is separated from the remaining the decomposition of lead carbonate in step (b) can be acetic acid solution to form a high purity normal lead separated and combined with ammonia to produce the carbonate filter cake. ammonium carbonate solution used in step (a). The In still another aspect of the present invention, there carbon dioxide formed as a by-product of the decompo is provided an improvement in a process for producing sition of lead carbonate in step (e) can be recycled for lead monoxide from solid lead sulfate bearing material. use in step (d). The acetic acid produced as a by-pro In the process, solid lead sulfate bearing material is duct in step (d) can be recycled for use in step (c). reacted with an ammonium carbonate solution to con In addition, lead chemicals such as lead chromate, vert said lead sulfate to lead carbonate. Substantially all lead arsenate, and lead tungstate can be prepared by 10 of the lead carbonate is then decomposed to impure lead precipitation from the lead acetate solution formed in monoxide.