SU517652A1 - Method for processing chlorine auger of solid non-ferrous and related metals - Google Patents

Description

firing gases. Increasing the temperature in the scrubber above 90 ° C is not rational.

Gases after emission of the main mass in the Venturi scrubber (90%) of chlorine extractors enter the wet electrostatic precipitator, where chlorine extractors are finally recovered. The combination of these two, successively operating apparatuses makes it possible to obtain almost complete trapping of chlorine extracts. The pulp from the scrubber and wet electro-hydrofluor, containing a mixture of chlorides and sulphates of heavy non-ferrous and related metals, is fed for calcination into a KS furnace, the bath of which is formed by grains of dry sulphates.

The furnace is heated by fuel combustion products that are simultaneously a fluidizing agent. The calcining of sulfate-chloride pulp at 400–500 ° C for 1–2 h ensures the completion of sulfatization of chlorides and almost complete removal of chlorine. The residual chlorine content in dry sulphates is below 0.05%. Dry sulphates containing copper, zinc, lead, gold, silver and other recoverable metals are sent for hydrometallurgical processing by known methods.

At the usual liquid flow rate in hydrometallurgy to dissolve sulphates (T: W 2-2.5), the resulting solutions do not require additional purification from chlorine before electrolysis. The firing gases from the calcining furnace and the wet electrostatic precipitator containing hydrogen chloride are fed to its capture and regeneration.

The main stage of sulfatization of chlorides and distillation of chlorine occurs, as studies show, in the process of their capture at 80-90 ° C. The residual chlorine content in the resulting pulp 5-7%. The calcining of sulfate-chloride pulp in this mode completes the process of sulfatization and distillation of chlorine. The process of sulfatization of chloride proceeds actively at the consumption of sulfuric acid with an excess ratio against the stoichiometric required 1.0-1.1 (1.05 preferably). The minimum excess of sulfuric acid is essential for the subsequent process of regenerating hydrogen chloride. The concentration of free sulfuric acid in the solution should not be lower than 140-160 g / l.

A decrease in the concentration of free sulfuric acid in the absorbing solution below 140 g / l leads to a decrease in the rate of its interaction with chlorides and an increase in the dissolution of free hydrogen chloride in the irrigation solution, as well as to a significant increase in fuel consumption during the subsequent evaporation of sulfate-chloride slurry.

The maximum possible concentration of free sulfuric acid in the irrigation solution, which is necessary from a thermal point of view during the evaporation of the sulfate-chloride pulp formed, is determined in each specific case of the process.

the conditions for cooling the circulating irrigating solution and the content of chlorine gas in the firing gases.

Example. A sample of cinder polymetallic rolls (after oxidative roasting) containing 1.2% Cu; 9.32% Zn; 5.7% of Pb, are subjected to chloride-burning roasting at 1020-1080 ° С with a capacity of 0.5-0.7 kg of calcine per hour. Burning gases containing chlorides of copper, zinc and lead, with a temperature of 700 ° C, enter the Venturi tube, irrigated with a solution of sulfuric acid (140 g / l) with a flow rate of 4 l / h. This ensures the waste gas temperature after the scrubber. Gases are additionally purified with a solution of H2SO4 (140 g / l). The degree of trapping chlorides 90%. The pulp containing chlorides and sulphates of recoverable metals is dried and calcined for 1 hour at 400 ° C. The residual chlorine content in sulphates is 0.04-0.06%. With an increase in temperature up to 500 ° C and an annealing time of up to 2 h, only traces of chlorine were detected, i.e., distillation was almost complete.

Thus, according to the chlorine content, the resulting sulfates can be subjected to electrolysis without further purification from chlorine.

The proposed method for the capture and processing of chlorides in the effluent has the following advantages:

the release as an intermediate product of extremely harmful, hygroscopic and inconvenient to handle dry chlorides of copper, zinc, lead and other recoverable metals is excluded;

Wet trapping with solutions containing not less than 140-160 g / l of free H2SO4 (in particular spent zinc electrolyte) at temperatures of 80-85 ° С ensures almost complete trapping of chlorine extracts with minimal dissolution of free hydrogen chloride in the irrigating liquid;

The use of KS furnaces for calcining sulfate-chloride pulp provides a continuous intensive process with the production of dry sulphates containing 0.05% chlorine and suitable for electrolysis without further purification of solutions from chlorine.

Claims (1)

A preliminary techno-economic analysis of the technological scheme for complex processing of metal-rich raw material of heavy non-ferrous metals using the chloride sublimation firing and trapping and processing of chloro-carbon bearers using this method, made on the basis of the conducted research, shows the high economic efficiency of the proposed method. For example, specific operating and capital costs are reduced by 10-12% each (based on the ruble of the cost of the ruble of marketable products). 5 The claims of the method of processing heavy non-ferrous and associated metals chlorine extracts, including trapping them from calcined gases followed by calcining, are also distinguished by the fact that, in order to simplify and intensify the process, complete regeneration of chlorine and obtaining 6 non-hygroscopic dry sulfates as intermediates. chlorine-free trapping of chlorides is carried out at 80-90 ° C with a solution containing 140-500 g / l of free sulfuric acid with an excess ratio of 1.0-1.1, and the resulting sulfate-chloride pulp is calcined and are carried out in a fluidized bed at 400-500 ° C for 1-2 hours in the environment of combustion products.