USE OF THE MODIFIED SORBENTS FOR EXTRACTION OF PRECIOUS METALS

摘要

The synthetic sorbents and the activated carbons which are used for the metals extraction from weak process liquors are rather expensive. It is propose to use mineral and synthetic high-porous substances which sharply increased sorption properties by special processing. For achievement the desirable properties sorbents are impregnated by specially prepared solutions. Such solutions should contain the substances or its anionic forms which on the one hand are strong enough fixed in a supporter pores, with another are capable to form the insoluble compounds with extracting metals. Selectivity is provided by chemism of the reagent interactions with extracting metal. Due to the high concentration of a reacting ion in a sorbent phase the capacity and rate of sorption increases. Formed insoluble compound remains in a phase of the sorbent and necessity of its filtration disappears. For synthesis the sulfhydryl compounds which chemical properties allow to increase degree of extraction and capacity of the activated carbon were used.At hydrometallurgical processing of precious metals mineral raw materials the commercial solutions with the concentration of gold from 0,1 to 5 mg/dm~3 are received. Commonly gold is precipitated from cyanic solutions by the zinc dust. The sorption methods are widely applicable. But the synthetic sorbents and the activated carbon using to these purposes are rather expensive. Expenses for sorbents even at its regeneration can reach 10-15 % from total expenses of gold extraction from ores. When sorbent regeneration, mostly for carbon, is not provided, this share increases to 30-40 %. Thereupon search of the sorbents combining availability, the sufficient capacity, demanded degree of extraction and the low price is actual. For the specified purpose it is offered to use the mineral and synthetic high-porous materials which sorption properties are sharply rose by special treatment. Among such substances are natural zeolites, silica gel, lignine et al. Similar treatment can improve the sorption properties of sorbents used in practice, particularly, the activated carbons. The simplest treatment of potential sorbents consists in its impregnation by specially prepared solutions. Such solutions should contain substances or its anionic forms - impregnating agents. These agents should be on the one hand strong enough fixed in a carrier pores, on the other hand are capable to form with extracting metals insoluble compounds. The more strong compounds are formed the high degree of metals extraction from solutions. The sorbents with similarly changed properties are named the impregnated sorbents.Whereas the concentration of the precious metals in the real solutions is much less than the concentration of the impurities which are not technological interested, the impregnation should be selective. Selectivity is provided by chemism of interactions of impregnating agent with extracting metal.Interactions of cations or complex ions of metals with impregnating agent differ from that in the bulk of the aqueous solution. In the phase of impregnated sorbent the concentration of reacting substances in tens and hundreds times higher, than in the solution bulk. Owing to this the capacity of the sorbent and the sorption rate are increased. The residual concentration of extracted metal sharply decreases. The forming insoluble compound remains in the phase of the sorbent and necessity of its filtration disappears.As the most obvious impregnating agent for extraction of precious metals the sulfhydric compounds or derivatives of O-ethers dithiocarbonic acids are considered [1]. Unlike sodium