DISPOSAL OF LEAD PRODUCTION WASTES BY EXTRACTION OF LEAD AND ZINC OXIDES

Information is given about the need to dispose of waste from the Shymkent lead plant in the form of slags, which have accumulated about 2 million tons. It is proved that lead production slags contain a large number of toxic compounds, such as lead, zinc, osmium, and cadmium, which are dangerous sources of environmental pollution. According to the results of X-ray diffractometric analysis and DTA, it was found that the slag of lead produc- tion contains a fairly high number of non-ferrous metal compounds: the content of lead oxide up to 2 %, zinc oxide up to 17% and copper oxide up to 1.25% of the total weight of the sample. The qualitative composition and content of non-ferrous metals of lead slags makes it possible to make the process of recycling toxic waste from lead production technically and economically feasible. The results of preliminary tests allow us to select a technology for more complete and selective extraction of lead and zinc oxides from the slag waste of lead production. When using a selective method for extracting non- ferrous metals, it is expected to improve the ecological state of the environment and reduce the negative impact on human health due to the disposal of toxic slags from lead production. At the same time, a significant contribution is made to the development of the system of rational use of natural and secondary resources.

ANALYSIS AND IMPACT OF LEAD-CONTAINING WASTE FROM LEAD PRODUCTION ON HUMAN LIFE AND THE ENVIRONMENT

As a result of the activities of the lead plant, about 2 million tons of waste in the form of lead- containing slags were accumulated. Lead production slags contain a large number of toxic heavy metal compounds, such as lead, zinc, osmium, and cadmium, which are dangerous sources of environmental pollution. Due to the open storage of slags, there is an excess of the maximum permissible concentrations (MPC) of lead: near the plant, the concentration of lead is more than 3000 mg/kg in the soil, with a MPC of 3.2 mg/kg. Lead and zinc compounds are dangerous to humans due to their significant toxicity and ability to accumulate in the body. Lead poisoning ranks first among professional intoxications. Waste water containing zinc compounds is not suitable for irrigation of fields, the negative effect of zinc compounds on microorganisms and microfauna of the soil reduces its fertility. The article presents the results of scientific studies of lead slag, conducted by scanning electron microscopy and X-ray microanalysis, performed on a scanning electron microscope (SEM) JEOL-6490 LV (Manufacturer: JEOL, Japan). The results of the thermal analysis of samples on the derivatograph of the F. Paulik, J. Paulik and L. Erdey system in the air environment, in the temperature range of 20-1000°C. are presented. According to the results of research, it was found that lead slags contain a sufficiently high amount of non- ferrous metal compounds: lead oxide up to 0.7 % and zinc oxide up to 8.5 % of the weight amount of slag, which makes the process of recycling toxic waste from lead production technically and economically feasible.

ANALYSIS AND PROSPECTIVE UTILIZATION OF TECHNOGENIC SLAG WASTE FROM A LEAD PLANT

The article presents the analysis and results of the study of technogenic slag waste of lead-zinc production. Slags of lead-zinc production contain a large number of toxic compounds: lead, zinc, osmium, cadmium, which are dangerous sources of environmental pollution. Due to the open storage of slags, it was found that the maximum permissible concentrations of lead were exceeded. Utilization of man-made slag waste is of great importance for reducing the negative impact on the safety of life and improving the environmental situation in the region. At the same time, slags are valuable raw materials containing compounds of non-ferrous and rare-earth metals. The article shows the results of laboratory studies of slags to determine the qualitative and quantitative composition of valuable components in the waste of lead production and the possibility of their further processing and disposal. Studies of the material of the heavy slag fraction were carried out on an electron probe microanalyzer of the JEOL IXA-8230 Electron Probe microanalyzer brand. X-ray diffractometric analysis of the average slag sample was performed on a DRON-4 diffractometer with Cu radiation, graphite monochromator. Samples were selected heavy fraction and manufactured artificial polished sections (briquettes). The sections were studied under the microscope of the brand LEICA DM 2500P and immersion in liquids. According to the results of research, it was found that lead slags contain a sufficiently high amount of non-ferrous metal compounds: lead oxide up to 0.7 % and zinc oxide up to 8.5 % of the weight amount of slag, which makes the process of recycling toxic waste from lead production technically and economically feasible.

DEVELOPMENT OF TECHNOLOGY FOR THE EXTRACTION OF LEAD AND ZINC OXIDES FROM DUST AND SLAGS DURING THE UTILIZATION OF LEAD PLANT WASTE

The object of the study is lead-containing slag dumps from a lead plant. The slags of the lead plant contain a large number of toxic compounds: lead, zinc, osmium, cadmium, which are dangerous sources of environmental pollution. Due to the open storage of slags, it was found that the maximum permissible concentrations of lead were exceeded. Utilization of lead production slags allows to obtain non-ferrous metals and to reduce the technogenic load on the environment as a result of processing of slags. At the same time, slags are valuable raw materials containing compounds of non-ferrous and rare-earth metals. The article proposes methods for the extraction of lead and zinc from slag waste and selects the optimal method for the selective extraction of zinc and lead oxides from dust and slags of lead production. The proposed technology of continuous carbon-free selective extraction of zinc and lead from the dust of electric steelmaking production allows the use of lead production slag, which is fed into a rotating drum furnace in two oppositely directed streams. During the movement of lead slag in the furnace drum and the burning of the torch, lead and zinc are more completely extracted from the dust-like material, where the transporting object is compressed air, and the purified flue gas after the gas is further purified by means of a smoke pump is released into the atmosphere. When using the proposed selective method for extracting non-ferrous metals, the ecological state of the environment will be improved, and it will also reduce the negative impact on human health due to the disposal of toxic slags from lead production.

Ways of the lead-bearing slag waste utilization

The article presents the results of research on the influence of lead production slag on the environment and ecology of the city. Due to the open storage of slags, an excess of maximum permissible levels (MPL) of lead was established: near the plant, the concentration of lead in the soil exceeds 3000 mg/kg, while the MPL is 3.2 mg/kg. The data of analyzes obtained by methods of scanning electron microscopy and X-ray microanalysis, performed on a scanning electron microscope (SEM), as well as the results of X-ray fluorescence semi-quantitative analysis, performed on an X-ray fluorescence wave-dispersive spectrometer, have been presented. The results of thermal analysis of samples in air in the 20-1000 °C temperature range are presented.It was revealed that lead slag contains a fairly high amount of toxic metal compounds. It has been established that the average content of toxic metals in slags formed as a result of the activity of a lead plant is: lead - 2, 38%; zinc - 9.81%; copper - 0.97%; iron - 25.31%; silicon oxide - 24.62%; calcium oxide - 16.21%; potassium oxide - 1.42%; sulfur - 1.35% of the total sample weight.The offered technology of a selective method for the extraction of non-ferrous metals allows to enhance the ecological state of the environment and reduce their negative impact on human health by means of the disposal of the lead production slags.

Processing of Sb-Pb-Sn-Containing Materials

During the processing of lead containing products and polymetallic alloys the recovery of tin and antimony from technology of lead production is carried out by oxidation refining of decopperized lead with rich oxides (Sn, Sb ≥ 20%).Tin oxides are melted in a short-drum furnaces to lead bullion (> 96% Pb) and tin-rich (> 20% Sn) slag. The slag is melted in an ore-smelting furnace to obtain a Sn-Pb alloy of next composition, %: 56.1 Sn, 18.2 Pb, 14.6 Sb, 6.9 As, which is refined by vacuum distillation with production of rough tin (Sn ≥ 90%). The additional profit of rough tin obtainment (∼310 tons/year), compared with sales of tin slag, is about ∼1.3 million $/year. Keywords: lead, tin, antimony, melting, vacuum distillation

Studying the impact of alkaline sulfide leaching parameters upon the efficiency of arsenic recovery from copper skimmings of lead production

The article is concerned with the problem of arsenic circulation as copper skimmings of lead production — the product of the lead bullion decopperization process at a metallurgical complex, uniting copper and lead plants. A brief overview of the methods of processing arsenic-containing middling products for the purpose of arsenic removal is given; the main advantages and disadvantages are indicated. The possibility of processing copper skimmings by the method of alkaline sulfide leaching with separation into arseniccontaining solution and lead-copper precipitate is studied. The results of the researches into the influence of temperature, process duration, solids content in the pulp, particle size, and the ratio of sodium hydroxide to elemental sulfur in the alkaline sulfide reagent on the process of alkaline sulfide leaching of copper skimmings af lead production are provided. Within the studied range of varied factors, the highest indexes of arsenic extraction into solution (85.04%) were achieved under the following conditions: temperature — 85 °C, duration — 4 hours, solids content in the pulp — 350 g/dm3, fraction (–0.08 mm), NaOH/S ratio = 100 g/100 g in 1 dm3 of the solution. The proposed method for processing copper skimmings will allow one to selectively isolate arsenic into the dump waste product during subsequent precipitation and separate contaminant from lead-copper cake, into which precious metals also pass. Such an approach provides the reduction of arsenic circulation between the lead and copper manufacturing facilities.