Improved treatment of lead chloride or basic chloride to convert it into other lead compounds, and application thereof to the winning of lead from ores, residues and the like

摘要

Ammonium chloride is produced by converting lead chloride into carbonate by means of ammonia and carbon dioxide. The lead chloride or a double chloride of lead such as lead ammonium chloride is suspended in a solution of ammonia and carbon dioxide is passed in. The first part of the reaction may be effected at about 30 DEG C. and the later part at a higher temperature such as 40-50 DEG C. Specification 3082/77 is referred to.ALSO:Lead chloride is converted into a carbonate by suspending in aqueous ammonia and passing in carbon dioxide. The lead chloride may be obtained by known methods from ores, concentrates &c. and is preferably used in finely divided form obtained for instance by grinding the crystals or by precipitation of a solution of lead chloride in a chloride solution by dilution with a large quantity of water; or a double salt such as lead-ammonium chloride may be used as such. The lead chloride may also be obtained by the treatment of metallic lead from residues with acid brine, hydrochloric acid, ferric chloride, or the like. The ammonium chloride in the mother-liquor may be crystallized by cooling and may be employed for the extraction of lead chloride from ores or may be heated with lime to recover the ammonia and obtain calcium chloride solution for treatment of lead ore. The conversion of the lead chloride into carbonate may be effected at about 30 DEG C. during the first part of the carbonation, and, when less ammonia remains free, at a higher temperature such as 40-50 DEG C. The carbonation may be effected on the counter-current principle. The mother-liquor containing ammonium chloride, ammonia, and carbon dioxide may be divided into two portions, one, called the nucleus solution, being made up to its original quantity with water, ammonia, and lead chloride for the next operation, while the other is treated to recover its constituents. In an example, zinc lead sulphide ores are roasted to sulphate the metals, the zinc is leached out as with a solution of sulphuric acid, and the residue, containing lead and silver sulphates, is treated with a hot chloride solution containing a little acid to extract the lead and silver. The silver is recovered in known manner, and the lead chloride is separated out by cooling and treated as above described. Specification 3082/77 is referred to. The Provisional Specification refers to Specification 210,463, [Class 2 (iii), Dyes &c.].