A method of processing lead waste containing precious and rare metals

 

(57) Abstract:

The invention relates to the field of non-ferrous metallurgy, in particular to a method of processing lead waste containing precious and rare metals. The method includes loading of waste in the mixture with a reducing agent in molten carbonates of alkali metals, melting and recovering of charge by 870-1050oWith the receipt of an alloy of lead containing precious metals that are extracted. In the remaining melt download carbonates of alkali metals, a new portion of the original charge and the process is repeated to accumulate in the melt at least 18% of arsenic, 2-10% selenium, 2-3% of tellurium, and then enriched with rare metal melt is poured. The ratio of the mass of waste and reducing agent in the melt support 1:(0.12 to 0.25), and the mass of molten carbonates and downloadable mixture of 1:(0.1 to 0,27). The method provides a comprehensive recycling of lead waste to produce free and concentrate rare metals, precious and rare metals can be extracted by known methods. 2 C. p. F.-ly, 4 PL.

The invention relates to ferrous metallurgy, in particular to methods for extracting noble metals and rare elements of lead waste in the form of miliciyasi the following process steps: low-temperature oxidation annealing, the purpose of distillation SeO2in the gas phase; the selective transfer of the sulfate forms of Pb in alkaline solution; cleaning solution from Pb, As, S, Te; melting Chekov leaching, concentrating noble and rare metals, together with the roasted slimes on the Au-Ag alloy. This method includes two pyrometallurgical operations and two hydrometallurgical, you want to capture from gas-phase selenium, used alkaline solutions.

The resulting cake on its own may not be used, but only as a Supplement to the burnt sludge medeelektrolitniy, and Nickel or Nickel-lead electrochemical processes.

Thus, this method is sequential, energy-intensive, using bulky equipment and aggressive solutions.

The method for extracting metals from rich lead anode sludge [2]. This method applies obesogenic to 2% or less of copper slurries containing more than 15% of lead sulfate in the form, as well as silver and other precious metals.

The sludge is mixed with solution of soda (10-150 g/l). The molar amount of sodium relative to the molar content of lead in the sludge should not be lower than 0.8:1. Then the sludge is separated from the solution and stirred in the solution in the slurry. The remainder of the sludge is separated from the solution and processed in any furnace in a known manner. A solution of H2SiF6mixed with H2SO4in a molar ratio of 0.5-1 in relation to the content of lead. After separation of the lead sulfate solution is directed to repeat the process.

The disadvantage of this process is a hydrometallurgical processing of sludge aggressive solutions (soda solution, a sulfuric acid, a solution of H2SiF6). Retrieved intermediates in the form of sludge, containing precious metals and sulphate of lead, for obtaining metals of which requires a separate pyrometallurgical processes.

There is a method of extraction of lead and silver from the tailings and process waste [3], in which waste containing lead in the form of sulphate and silver in the form of native silver, silver chloride, sulfide or sulfate, as well as in the form of complex compounds with other metals, are formed during the roasting and leaching of sulphide concentrates containing lead, zinc, copper and silver.

Waste is treated with brine, the resulting solution is treated with lime to precipitate the lead as the oxychloride. The precipitate is fired to obtain a mixture of orthophosphate calcium is t in the shaft furnace for melting lead, to extract the lead and associated silver in elemental state.

The main disadvantage of this process is its multi-stage to obtain free (an alloy of lead containing precious metals), as well as the presence of hydrometallurgical operations.

The closest in technical essence and the achieved result is a method of recycling of lead containing antimony, tin and copper, including downloading the source charge and the carbonaceous reductant in the molten salt of alkali and alkaline earth metals, the melting of the charge, the recovery of metals and receiving alloys lead-based [4].

However, the known method does not allow direct extraction from the waste of precious metals in a separate product because of the high copper content and complexity of subsequent processing of an alloy containing copper and precious metals.

In addition, according to the method for accumulation of rare metals to concentrations that ensure its further processing and production of rare metals by traditional methods, it is necessary to process a very long period (up to several tens of hours).

Technical resulting waste containing precious and rare metals, to obtain the alloy of noble metals and concentrate containing rare metals, then extract all the metals by known methods.

This technical result is achieved in that in the method of processing lead waste containing precious and rare metals, including downloading the source material and the carbonaceous reductant in molten carbonates of alkali metals, the melting of the charge and recovery of metals, according to the invention, the recovery is carried out at 870-1050oWith the receipt of an alloy of lead containing precious metals, which is extracted from the melt, then additional load carbonates of alkali metals, a new portion of the original charge and the cycle is repeated until reaching the melt at least 18% of arsenic, 2-10% selenium, 2-3% of tellurium, and then enriched with rare metal melt is poured, the ratio of the mass of waste and reducing agent in the melt support 1:(0.12 to 0.25), and the ratio of the mass of molten carbonates to the charge- 1:(0,1-0,27).

From the resulting free (an alloy of lead with noble metals noble metals are recovered by conventional means, and arsenic, selenium, tellurium and other rare is the extraction of arsenic and rare items load operation raw materials and wylewki repeat as many times to melt salts have accumulated not less than 18% of arsenic, 2-10% selenium, 2-3% of tellurium, which allows their subsequent retrieval by classical methods.

Tests showed that almost complete separation of two products: lead with noble metals in the form of the free and the melt salts, arsenic, selenium and tellurium.

The melt salts easily soluble, and it is possible fractional crystallization to isolate the individual compounds of selenium, tellurium and arsenic.

Full recovery of precious metals in the alloy of lead is carried out at 870 - 1050oC and holding time is not less than two hours.

Lowering the temperature below 870oC leads to a decrease in the extraction of lead and associated precious metals, increasing the temperature above 1050oWith leads to volatilization of salt and increasing the consumption of salt. Also the exponents of the recovery of precious metals by the reduction of the declared shares of the reducing agent relative to the weight of the feedstock, increasing the proportion of reducing agent leads to an increase of voshon salts due to the interaction of carbon with carbonates.

Special experiments and thermodynamic calculations set, Thu the gas phase, and goes into the lead alloy in large numbers. Selenium can accumulate up to 2-10%, and tellurium up to 2-3%, which allows their complete removal from the melt.

In addition, in the proposed new process is a joint recovery of heavy non-ferrous and precious metals and accumulation of the last in the free, where they are extracted by the known methods.

Also new is the accumulation of trace elements in carbonate melt to concentrations when they can extract in a small volume of solution, with high extraction into separate elements.

The stated ratio of raw materials reductant, and a single portion of downloadable raw material to the mass of molten carbonates and the optimum temperature of the process contribute to a more complete transition metals in the partial intermediates.

Example 1. In the shaft furnace resistance established the crucible of beryllium oxide, which has been downloaded 90 g Na2CO3and 30 g2CO3the mixture is melted and heated to 875oFrom, downloaded to 15.4 g of lead, to create "pools" at the bottom of the crucible, and then four reception downloaded the mixture of dust (40 g) and charcoal (6 g). After loading the melt was kept for 40 min and maintain the oWith aging from download dust to notch 1,28 including the composition of the loaded dust (wt.%): Pb - 30,6; Sb - 0,32; Sn was 7.36; Cu - 1,89; Zn - 21,84; Bi - 0,23; Au 8 to 10-4; Ag - 1,69-10-3. The composition of the obtained products are shown in table. 2 and 3 (experiment 14).

Received of 20.3 g of lead (increase metal 4.9g), or 110.3 g of salt. The analyses in the metal moved 23,26% Au and 86,67% Ag, the rest remained in the salt melt. The free was removed lead - 73,4%.

Example 2. In the furnace of resistance established the crucible of beryllium oxide, downloaded 90 g Na2CO3and 30 g2CO3, melted, downloaded 16.7 g of lead, was heated to 985oWith and portions in four installments have downloaded the charge of the dust mixture of the previous compound (40 g) and charcoal (6.5 g). The average temperature of the experience was 1004oC, the exposure time of 1.25 hours the salt Melt was poured into a mold, cooled, and separated bead free of lead, weighed. The metal salts were analyzed.

Received of 21.6 g of an alloy of lead and 98.9 g of the salt water. The results of the analysis are given in table. 3, 4 (experiment 15). The growth of metal was 4.9 g, and removing the lead from dust - 75%, gold - 73,05%, silver - 88,01%.

Example 3. In the experimental shaft furnace resistance with sheltowee heaters placed the crucible of siliciano 3, melted, heated to 840oWith, downloaded the Pb-Sb alloy in the number 2390 g; in the alloy contained 1.8% of Sb, he formed on the bottom layer of 30 mm In the molten salt downloaded the charge of the dust from the filter HKDI in the number 16,34 kg and 3.7 kg of charcoal, crushed 8-10 mm during the experiment the mixture was loaded portions of 700-800 g, 15-20 minutes during the experiment, added 2 more kg TO2CO3and 1 kg of Na2CO3. The average temperature of the experience was 917,6oC. the Entire mixture was loaded into a 25 receptions for 7,66 PM

Above the stove was installed device made of steel mesh to capture parts of zinc dust, with subsequent analysis.

After the oven has cooled, broke the crucible and learned to 7.93 kg lead alloy, 1 kg afloat salts. The composition of the original dust was as follows, wt.%: C - 0,98; Zn - 35,1; S - 5,02; Pb - 24,6; Sn - 9,19; Fe - 0,41; As - 0,88; Au and 0.8 g/t; Ag - 104,8 g/so

The growth of metal amounted to 5.56 kg, removing 98%. The composition of the metal and salts shown in table. 3, 4. The composition of the sublimates zinc, wt.%: Pb - 9,8; Sb - 0,12; Sn - 3,12; Cu - 1,3; Zn - 40,7; Au - 1,74 g/t; Ag - 8 g/T. the Number of sublimates 6 kg. Balance all 3 products gives the following results (see tab. 1).

Example 4. In mine Selidovo oven installed the crucible of siliconized graphite, downloaded the melirovanie gold and silver, survived 2.5 hours and poured the contents into the mold. The alloy of lead separated from the salt water, weighed, and the alloy and the melting salts were analyzed (results in table. 2, 3, 4. Experience 46).

The composition of the dust next, wt.%: C - 0,18; Sb - 12,8-17,0; As - of 4.44; Pb - 32,0-46,0; Those Is 1.91; S - 3,8; Se - 1,59; Au from 5.0 g/t to 140.0 g/t; Ag -15365 g/so

Received 135 g of an alloy of lead and 400 g of water salts. In lead alloy has passed 100% of gold and 99.99% silver. Restored 97, 28% of lead, 78% antimony, selenium left in salt water, and tellurium as follows: 71,7% in water salts and 28.3% in lead alloy. Arsenic also remained in the salt water.

Sources of information

1. Belenky, A. M. and other Complex use of mineral raw materials. 1981, 3, S. 30-34.

2. Patent Poland 144849, MKI 22 B 7/00, 31.01.81.

3. Application EP 0042702, MKI 22 B 13/00, 11/00, 30.12.81.

4. RF patent 2114200, 22B 7/00, 27.06.98.

1. A method of processing lead waste containing precious and rare metals, including downloading the source material and the carbonaceous reductant in molten carbonates of alkali metals, the melting of the charge and recovery of metals, characterized in that the recovery is carried out at 870-1050oWith the receipt of an alloy of lead, with which cnyh metals, a new portion of the original charge and the cycle is repeated until reaching the melt at least 18% of arsenic, 2-10% selenium, 2-3% of tellurium, and then enriched with rare metal melt is poured.

2. The method according to p. 1, characterized in that the ratio of the mass of waste and reducing agent in the melt support 1:(0.12 to 0.25).

3. The method according to p. 1, characterized in that the ratio of the mass of molten carbonates and masses of charged metal support 1:(0.1 to 0,27).

 

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