Effect of calcium and thiosulfate ions on flotation selectivity of nickel–copper ores

Effect of calcium and thiosulfate ions on flotation of a Ni–Cu ore was investigated. The ions improved the flotability of sulfides at the normal process pH after grinding in steel mill. Calcium activated especially nickel and copper sulfides when the galvanic effect of mill iron was effective. The UV/Vis measurements showed that calcium ions increased xanthate adsorption on the sulfides. The effect of thiosulfate was different. It was concluded that thiosulfate reduced the effect of hydrophilic compounds on sulfide particles, and in that way improved their flotation.     

Grey associated analysis of the underground water quality effected by the leaching water of dumping area or hillock of coal mine

The underground water has been contaminated seriously by the leaching water of dumping area or hillock. To determine the pollution limits of underground water, author took samples in the study area, analyzed samples for water quality, assessed the water quality of each monitoring point by the grey associated analysis method, and gave out the classifications of the underground water quality of the study area. Comparing with fuzzy comprehensive appraisal method, it is demonstrated that grey associated analysis method is applied easily, because of its clear concept, simple and convenient calculation and excellently operation.     

Collectability of physically adsorbed xanthate ion–dixanthogen associates

Under discussion is collectability of ethyl and butyl xanthate species resulted from nonstoichiometric interaction with oxidizer. It is visually proved that solution contains fine micro-drops stabilized by negative charge. The size and ζ–potential of micro–drops are determined together with the spreading velocity of emulsion over water surface. The mentioned velocity is higher than the spreading velocity of products of non-stoichiometric interaction between xanthate and heavy metal salt. The products of interaction between xanthates and oxidizers are known as desorbable species (DS), as at the moment of rupture of water film between mineral particle and air bubble they can detach from particle surface and attach to air–water interface. Spreading of DS over the interface forces water out of the film. The forces applied to liquid in the film from the side of DS of ethyl and butyl xanthates are evaluated. The volume–flow rate of water from the film is related with the surface pressure of reagent species active at the air–water interface. The surface pressure of dixanthogen–xanthate emulsion is evaluated as a function on initial concentration of xanthate. Collectability of the reagent depends on the surface tension of DS solution and is governed by the structure of hydrocarbon fragment of the agent.     

Digestion kinetics of arsenic removal from enargite–tennantite concentrates

Copper sulfide concentrates with high contents of deleterious impurities such as arsenic and antimony must be pretreated before conventional smelting to prevent atmospheric pollution with toxic compounds. In this work, the selective removal of arsenic and antimony from enargite–tennantite concentrates by a hydrometallurgical process was studied. The process consists of an alkaline digestion using a small volume of concentrated NaHS–NaOH solutions to obtain soluble arsenic and antimony compounds and insoluble copper sulfides. The soluble arsenic and antimony is separated from the copper sulfide by water leaching of the digested material. The experiments were carried out using a copper–arsenic concentrate with 15.1% As and 1.42% Sb. The results showed that the digestion temperature and the concentrations of NaHS and NaOH were the most important variables affecting the rate of arsenic and antimony removal. The rate of the digestion reaction was analyzed by using the unreacted shrinking core model controlled by the diffusion of S²⁻ ions through the layer of the product copper sulfide. An experimental activation energy value of 57 kJ/mol was determined for the arsenic removal in the range of temperature of 60–90 °C.     

Seismic–Geomechanical Control of Water-Impervious Strata in Potassium Mines

The safety control system for water-soluble mineral mining in complicated ground conditions is presented. The system is based on geomechanical interpretation of surface and underground seismic monitoring data. Mathematical modeling of water-impervious strata takes into account the whole set of geological and geotechnical factors determined from the seismic observations. It is shown that the seismic–geomechanical monitoring allows stress state control in waterproof strata, which ensures prompt decisionmaking on extra protection and minimizes accident risks.     

Quantitative estimate of rotary–percussion drilling efficiency in rocks

The factors that have significant influence on efficiency of rotary–percussion rock drilling with downhole machines are discussed. The results obtained in physical simulation of dynamic driving of rock-breaking indenters in rocks are reported. The results are analyzed from the standpoint of the phenomenon of alternating response of rocks to dynamic impacts.     

Analysis of Two-Phase Gas–Water Flow in Carbonate Reservoirs

Gas–water relative permeability (GWRP) is measured in the tests of full-diameter cores. Based on the obtained GWRP curves, the standard normalized curves are plotted for three types of carbonate reservoirs: matrix pore, fracture and solution pore. The corresponding gas and water two-phase flow model was deduced by considering stress sensitivity and non-Darcy effect, and the IPR curve calculation and analysis of gas wells of the three types were carried out. Based on huge gap between the matrix and fracture permeability, the phenomenon of gas drive water mainly exists in the cracks. So the conventional gas–water relative permeability of fractured gas reservoirs was modified.     

Predictive analysis of slope stability of internal dumps in Tamnava–West field mine after flooding

The article reports the results of estimation of internal dump slope stability in flooded open pit coal mine Tamnava–West Field. The geostatic analysis of stability used methods by Bishop and Morgenstern–Price. The studies confirm that slopes of internal dump are sufficiently stable and sustain stability after drainage of the open pit.     

Selection of load–haul–dump machines for hard mineral mining in difficult mining and geological conditions

In focus is selection of load–haul–dump machines for hard mineral mines. The authors offer substantiation procedures for tuck-and-shovel systems of mining in difficult ground conditions. In terms of Kyrgaisky Sredni open-cut located in the Erunakovo coal district in Kuzbass, using the Lerchs–Grossman algorithm, the principles and sequence of forming efficient application domains for different specification trucks and shovels within a mine field are presented.     

A study of bubble–particle interaction using atomic force microscopy

Interaction between solid particles and air bubbles is central to froth flotation. Measurement of such interaction forces has only recently been possible with the invention of the atomic force microscopy (AFM). In this paper, the AFM colloidal probe technique was used to measure hydrodynamic interaction forces between a solid sphere attached to an AFM cantilever and an air bubble placed on an AFM piezoelectric stage at different approach speeds. Strong repulsive forces due to the hydrodynamic interaction were established and quantified for both hydrophobic and hydrophilic particles, and bubbles in deionised water and 1 mM KCl aqueous solutions. No surfactants were used. In the case of hydrophobic spheres, strong attraction between the surfaces, in addition to the repulsive hydrodynamic force, was observed, leading to the rupture of the intervening water film due to submicroscopic bubbles and the attachment of the particle to the air bubble at relatively large separation distances, which were of the order of 500–2000 nm. In the case of hydrophilic spheres, the rupture of the intervening water film and the attachment of the particle to the air bubble did not take place. An analysis of the AFM data was carried out to obtain the interaction force and relative separation distance. Theoretical hydrodynamic force calculation shows agreement with experimental data for larger separation distances. Deviations at shorter distances are related to the deformation of air–water interface due to the particle approach and surface forces.     

Hydrothermal precipitation of arsenic compounds in the ferric–arsenic (III)–sulfate system: thermodynamic modeling

It is known that Fe (III) and As (III), through in situ oxidation, can precipitate to form a crystalline ferric arsenate under specific conditions of temperature and pH. A thermodynamic model is built to investigate this process. The development and the use of chemical speciation model have lead to simulate the distribution and the concentration of chemical species of the ferric–arsenate (III)–sulfate system at 293.15–553.15 K temperatures range. The modeling predictions are compared to experimental data measured by the authors. It was shown that a reasonable prediction could be made if different modeling approaches are used. The paper compares different approaches in thermodynamic modeling and discusses also the validity of different extrapolation models used at high temperatures.     

The Use of Tecflote Family Collectors in Copper–Nickel Ore Flotation

Journal of Mining Science - Tecflote non-ionic organic agents are investigated as potential flotation collectors for copper–nickel sulfide ores. Adsorbability of four Tecflote agents having...     

Gold and arsenic recovery from calcinates of rebellious pyrite–arsenopyrite concentrates

The products of stepped calcination of pyrite–arsenopyrite concentrates contain ferric arsenate phases FeAsO₄, Fe₄As₂O₁₁, Fe₃(AsO₄)₂. The article reports the research data on leaching of calcines in alkaline medium including caustic soda and hydrogen peroxide used as an oxidizer. The experiments prove the efficiency of alkaline leaching with H₂O₂ for dissociation of gold associated with ferric arsenates (II) and (III) and for reduction of arsenic content from 1.2–1.4 to 0.006–0.15%. Preliminary leaching of calcinates enhances gold cyanidation yield from 91–92.9 to 97.3–97.9%.