Utilization of steelwork waste heaps – recovery of metals by acidic bioleaching

Bioleaching and recovery of metals from final slag waste of the copper smelting industry

Dry shot blast generated during stainless steel production contains high content of valued metals such as iron chromium and nickel. These metals are in the form of oxides and it can be used as a raw material in iron and steel. This work aims to study the feasibility of metals recovery from dry shot blast by smelting reduction process. Smelting reduction of dry shot blast by using coking coal as reductant was conducted in an induction furnace. The effect of metallurgical parameters e.g. stoichiometry ratio of reductant per oxygen containing in dry shot blast, CaO/SiO2 of slag forming and CaF2 in slag, on %recovery of metal product was investigated. The results based on this study showed that the weight of metal product increases with increased the amount of coke to about 1.5 of stoichiometric molar ratio. Increasing of coke above this amount leads to decrease %recovery of metal product. Moreover, the weight of metal product is increased when the ratio of CaO/SiO2 in slag decreased from 2 to 1. The chemical composition of the metal product is in the range of commercial grade and it can be used as raw materials to produce steel and cast iron alloy.Dry shot blast generated during stainless steel production contains high content of valued metals such as iron chromium and nickel. These metals are in the form of oxides and it can be used as a raw material in iron and steel. This work aims to study the feasibility of metals recovery from dry shot blast by smelting reduction process. Smelting reduction of dry shot blast by using coking coal as reductant was conducted in an induction furnace. The effect of metallurgical parameters e.g. stoichiometry ratio of reductant per oxygen containing in dry shot blast, CaO/SiO2 of slag forming and CaF2 in slag, on %recovery of metal product was investigated. The results based on this study showed that the weight of metal product increases with increased the amount of coke to about 1.5 of stoichiometric molar ratio. Increasing of coke above this amount leads to decrease %recovery of metal product. Moreover, the weight of metal product is increased when the ratio of CaO/SiO2 in slag decreased from 2 to 1. The chemical composition of the metal product is in the range of commercial grade and it can be used as raw materials to produce steel and cast iron alloy.

Recovery of metals in a double-stage continuous bioreactor for acidic bioleaching of printed circuit boards (PCBs)

The effect of flotation and parameters for bioleaching of printed circuit boards

Bioleaching of the α-alumina layer of spent three-way catalysts as a pretreatment for the recovery of platinum group metals

There were presented results of mineral and chemical composition of ash and slag waste study from Aleksin CHP (Tula Region). There was proposed scheme of ash and slag waste treatment for the purpose of separation of particles not contained rare earth metals (REM) as well as contained REM, for increase of recovered elements in ashes. For preliminary concentrating of valuable elements in ashes and slags, as experimental studies shows, we should carry out treatment of ashes and slags on concentrating table with subsequent magnetic or electromagnetic separation. Preparation of ashes and slugs under a proposed technique allows substantially increase recovery of precious and rare earth metals from ashes and slugs on the average by 10-25 % as well as decrease volume of treated semi-products, and hence, increase productivity of plant for bacterial leaching of metals.

There were considered possibilities of rare earth metals recovery from ashes and slag, predominantly from energy industry. There were carrying out laboratory research that showed that it is possible recovery of rare earth metals from ashes and slag of CHP plants by means of native species acidophilic chemolithotrophic microorganism populations. Data of this research could serve as the basis for mode adjustment and technology development for rare earth metals extraction from ashes and slag of CHP plants by means of biotechnology technique usingnative species acidophilic chemolithotrophic microorganism populations. There was also offered a possibility of developed approach’s implementation in pilot conditions using combined flotation devices, i.e. flotation plant, with description and mode of operation. Application of proposed unit allows to increase leaching degree of the rare earth metals by 15-20 per cents in comparison with conventional devices.

Many of the secondary raw materials (SRM) in landfills constitute valuable and scarce natural resources. It has already been recognised that the recovery of these elements is critical for the sustainability of a number of industries and SRM recov¬ery from anthropogenic waste deposits represents a significant opportunity. In this study, the characterisation of the different waste fractions and the amount of SRM that can potentially be recovered from two landfill sites in Finland is presented. The first site was a municipal solid waste (MSW) landfill site and it was specifically in¬vestigated for its metals, SRM, plastics, wood, paper, and cardboard content as well as its fine fraction (<20 mm). The second site was an industrial landfill site contain¬ing residual wastes from industrial processes including 1) aluminium salt slag from refining process of aluminium scrap and 2) shredding residues from automobiles, household appliances and other metals containing waste. This site was investigated for its metals and SRM recovery potential as well as its fine fraction. Results suggest that the fine fraction offers opportunities for metal (Cr, Cu, Ni, Pb, and Zn) and SRM extraction and recovery from both landfill site types while the chemical composition of the industrial waste landfill offered greater opporutinity as it was comparable to typical aluminium salt slags. Nevertheless, the concentrations of rare earth metals (REE) and other valuable elements were low even in comparison with the concentra¬tions found in the Earth’s crust. Therefore mining landfill sites only for their metals or SRM content is not expected to be financially viable. However, other opportunities, such as waste-derived fuels from excavated materials especially at MSW landfill sites, still exists and fosters the application and feasibility of landfill mining.

5531970 Metal and fluorine values recovery from mineral ore treatment

Pathway to industrial application of heterotrophic organisms in critical metals recycling from e-waste

In typical zinc & lead production operations, lead blast furnace slags and zinc leaching residues are usually fumed to recover zinc metal. Regardless of the fuming methods employed, the tail slag from zinc fuming furnaces still contains about 3 per cent or more zinc and some trace amounts of elements such as lead, indium and germanium. Although by traditional measures the contents of Zn, Pb, and the rarer elements In and Ge are very low, in absolute terms there is still the potential to extract considerable value from these remaining metals. As well, the elimination of these heavy metals from the slag would go even further in ensuing that the slags can be used as cement additives, landfill, roadbed material, etc. without environmental ramifications. A new electrochemical process, similar to the Hall-Heroult process in aluminum production, has been proposed for the recovery of metal values from this slag. Based on thermodynamic analysis and F*A*C*T calculations, copper melt was chosen as the cathode because it significantly decreases the activity of zinc while increasing the activity of iron. The results of synthetic slags (24.4 pct-Fe 39 pct-Si02 17 pct-CaO 6 pct-Al₂0₃ 2 pct-Zn) at 1250 °C revealed that 1) even without passing a direct current, a certain amount of zinc was diffused into the copper melt by the predicted thermodynamic driving force; 2) zinc was continuously deposited into the copper melt by electrochemical reaction when the voltage difference between the electrodes was 4 volts or greater. The effects of temperature and basicity on the process have also been studied. By the results of Fe ³⁺/Fe ²⁺ analysis and SEM examinations, possible reaction mechanism have also been suggested. The as-received Cominco tail slags were also examined by electrolysis.

The problem of using waste steelmaking slags as a technogenic source of metallurgical raw materials still has no sustainable solution and requires innovative ideas and approaches. The purpose of this paper is a theoretical and experimental study of the possibility and expediency of the preliminary heat treatment of steelmaking slags in a reducing medium for greater metal recovery. The subject of research is a slag sample taken from the slag heaps at Zlatoust Metallurgic Plant (the Russian Federation). To perform thermodynamic simulation of the processes running during heat treatment of a slag substance, the FactSage software package (version 6.4) was applied. For the ease of analysis the key calculation results are presented as a logarithmic dependence of component weights and composition of the considered phases on temperature. The experimental studies include heat treatment tests on slag samples at temperatures of 1100 and 1200°C in air and in the carbon monoxide medium with further separation of the derived product. The composition of test samples is determined by electron microprobe analysis and X-ray diffraction analysis. It has been reported that heat treatment in carbon monoxide medium makes possible to significantly increase the iron content in the derived magnetic fraction. The results of thermodynamic simulation, composition analysis of samples and weight data for the obtained magnetic fractions (resistant or non-resistant to the magnetic field) suggest that the preliminary heat treatment of slag in carbon monoxide medium is expedient.

Metallic Materials From E-Waste