Recovery of Valuable Metals from Nickel Smelting Slag Based on Reduction and Sulfurization Modification

Nickel smelting slag contains valuable metals including nickel and copper. Failure to recycle these metals wastes resources, and disposal of nickel slag in stockpiles results in environmental pollution. Nickel slag recycling is important, and metals can be recovered from slag by flotation. However, considering the complex forms in which valuable metals occur in nickel slag, high yields are difficult to achieve by direct flotation. In this study, nickel slag was modified by reduction and sulfurization to render it more amenable to metal recovery through flotation. The mechanism was assessed based on thermodynamics and elements’ phase distributions. Thermodynamic analyses indicated the feasibility of nickel slag modification by reduction–sulfurization smelting. The results of chemical phase analysis show that the forms in which valuable metals occur in nickel slag can be modified by reduction–sulfurization, and the proportion of metals existing in sulfide and free metal states in nickel slag can be increased. Compared with the direct flotation of raw slag, the recovery of nickel and copper from top-blowing slag increased by 23.03% and 14.63%, respectively. The recoveries of nickel and copper from settling slag increased by 49.68% and 43.65%, respectively.

Compósito de resíduos de mineração com cimento e cal para materiais de construção sustentáveis

<p> <span class="fontstyle0">Sustainable alternatives have been developed with the use of waste in construction, among which we can highlight mining waste due to its large amount generated and environmental impact caused. This work consists in the joint application of scheelite residue and stone powder with lime and cement addition, producing cylindrical specimens, to evaluate possible uses in constructive materials. After chemical and physical characterization, the percentage of each residue was determined through the analysis of packing between the particles, which resulted in a formulation of 50% of each residue with the addition of cement and / or lime in the contents of 6% and 12%. Essays for simple compressive strength (SCS), water absorption (WA) and chemical phase analysis by scanning electron microscopy (SEM) and X-ray diffraction (XRD) were evaluated at determined cure times. The SCS essays results of formulations with residues and cement reached values above 1 MPa and WA essays results with value below 20%, according to the Brazilian technical standards. Cement phases were observed in SEM and XRD analysis. The results obtained from mixing the waste with the cement are promising for the manufacture of cement building materials.</span> <br /><br /></p>

Comparative Study on Two Pretreatment Processes for Chemical Phase Analysis of Gold in Geological Samples by Atomic Absorption Spectrometry

Sample pretreatment is important for chemical phase analysis of elements. In this study, the geological samples of the Laozuoshan gold mine are chosen to pretreat by ultrasonic centrifugation and cyclotron oscillation, and the content of gold in eight chemical phases (water-soluble, ion exchange and clay adsorption, organic matter bound, iron-manganese oxide bound, naked or seminaked, carbonate bound, sulfide bound, and insoluble silicate states) is determined by atomic absorption spectrometry. The results show that the gold content of water-soluble, ion exchange and clay adsorption, iron-manganese oxide, and naked or seminaked states in the rock and ore samples is low, and some samples have high gold content of insoluble silicate states in the two methods. However, the gold content of organic matter bound, carbonate bound, and sulfide bound states obtained by ultrasonic centrifugation and cyclotron oscillation methods is significantly different. According to the X-ray fluorescence spectrometry data and the actual geological condition, the result given by the cyclotron oscillation method is more reasonable. The gold content of sulfide bound state in sediment samples is the highest and consistent with the mineral information, which could be applied to preliminarily predict the rock and ore conditions in the corresponding mining areas. In contrast with ultrasonic centrifugation, the cyclotron oscillation method has the advantages of simplicity, high efficiency, practicality, and environmental protection, and it can be better used for the determination of gold chemical phase state in geological samples by atomic absorption spectrometry.

Synthesis and Characterization of CaxSryBa1-x-yFe12-zLazO19 by Standard Ceramic Method

The polycrystalline compounds with chemical formula CaxSryBa1-x-yFe12-zLazO19 (CSBFLO) were synthesized via standard ceramic method. The chemical phase analysis was carried out by X-ray powder diffraction (XRD) method, which confirmed the formation of the magnetoplumbite phase belonging to ferrite structure. The frequency dependence of AC conductivity and dielectric constant was studied in the frequency range of 10 Hz to 2 MHz. The experimental results revealed that AC conductivity increases with increasing frequency, which is in agreement with Koop’s phenomenological theory. However, variation in dielectric constant required explanation in light of dielectric polarization. Magnetic characterization included studies of parameters such as Ms, Mr, Hc, and Tc, and results were explained via magnetic dilution and canting spin structure.

Research on Process Mineralogy of some Pyrite Cinder

The characteristics of process mineralogy of some pyrite cinders were studied with optics microscopes, scanning electron microscope, and x-ray diffraction. The chemical composition and the phase composition of the pyrite cinders were analyzed. The occurrence and chemical phase analysis of molybdenum of iron, copper, and gold were also studied. The behaviors of various minerals and mineralogical factors affecting the separation had been explained clearly. The investigation results were favorable to reasonable selection of technological process.

Research on Chloride Leaching of Cu, Zn and Ag from Flotation Tailings

Mineralogical examinations of Asheler copper mine flotation tailings have been carried out. Results show that the major metal sulphide minerals are pyrite and the main gangue constituents are quartz, chlorite-serpentine and muscovite. The main valuable metals are Cu, Zn and Ag. Basic mineral compositions of copper and zinc have been identified through chemical phase analysis. On the basis of mineralogical examinations, leaching test has been carried out in about 240g/l NaCl solution. The optimum conditions for leaching are found as follows: temperature at 86°C, pulp concentration is 24.19%wt, [Cu2+] =19.22g/l, [HCl] initial =0.17mol/L. Under these conditions, chloride leaching can extract 83.35%Cu, 92.10%Zn, and 85.26%Ag after 8 hours leaching.