Thermodynamic modelling of roasting of molybdenum sulphide concentrate with calcium hydroxide

This work aims to determine the conditions for the CaMoO4, CaSO4, Ca(ReO4)2 formation during oxidation of MoS2 and ReS2 in the presence of Ca(ОН)2. The concentrate from the Yuzhno-Shameyskoye deposit in the Sverdlovsk region, having 37% wt. Мо and 0.005% wt. Re, was selected as a feedstock for thermodynamic modelling of sweet roasting in the presence of Ca(OH)2. To determine the optimal amount of calcium-containing additives, the thermodynamic modelling was carried out using the following mass ratios: molybdenum concentrate: Ca(OH)2 = 1:0.8, 1:1, 1:1.2 and 1:1.5 in the temperature range of 100–800°С, with a step of 100°С, system pressure of 0.1 MPa in the air (molar ratio: molybdenum concentrate + Ca(OH)2: air = 1:5). The content of all sample components in moles was entered into the HSC 6.1 software package. The main reactions associated with the sweet roasting of molybdenum concentrate in the presence of calcium hydroxide were shown. It was established that the main phases formed as a result of roasting comprise CaSO4, CaSO3, MoO3, CaMoO4, CaMoO3 and CaReO4. The effect of temperature on the formation of the main gaseous products was studied under different mass ratios of molybdenum concentrate and Ca(OH)2. It was found that up to 600°C, with molybdenum concentrate to Ca(OH)2 ratio of 1:1, the concentrations of released sulphurous anhydride are lower than the maximum permissible concentrations. The calculated thermodynamic data was used for modelling the roasting process of molybdenum concentrate with calcium hydroxide. An optimal ratio necessary for the successful process operation was established: molybdenum concentrate: Ca(OH)2 = 1:1 by weight. Thermodynamic modelling showed that, in the temperature range of 100–600°С when using Ca(OH)2, no rhenium and molybdenum loss is observed, the release of sulfur is less than 10 mg/m3.

The Inadvertent Activation of Silicate Minerals Flotation and Their Depression in Molybdenite Beneficiation

The Wushan Operation has been studied as a case study, particularly relevant to the copper-molybdenum separation circuit, in which efforts have been made to improve the quality of the molybdenum concentrate through diagnostic analysis. A key finding has been the appearance of coarser silicate minerals in the molybdenum concentrate due to their inadvertent activation in flotation. The suitable silicate minerals flotation conditions occurs, most likely, due to upstream bulk flotation regarding the usage of novel collectors and metal cations bearing process water. The flotation of silicate minerals can be diminished by the implementation of water glass and regrinding. The mechanisms underlying flotation behaviors have been revealed by using advanced in-situ surface analysis and particle size analysis techniques.

Modified Collector: New Approaches

The process of complex raw materials is currently characterized by the fine-dispersed mineralogical structure and difficult structural characteristics complicating the flotation process. In this study, the processing methods for flotation of Aktogay deposits of copper-molybdenum ore were performed by using basic and modified agents. The properties of modified collector based on Kumkol deposit and diesel fuel were studied using the standard methods. The testing technology included the grinding of initial ore to a particle size of 65% of the class -0.074 mm, collective flotation to produce coarse copper-molybdenum concentrate, desorption, regrinding of the collective copper-molybdenum concentrate to 95% of the class -0.074 mm, selection of the collective concentrate. It was established that this application increased the extraction of copper/molybdenum concentrate by 3.8 % without loss of concentrate quality. This technology is applicable to mining and beneficiation enterprises processing molybdenum ores. Keywords: copper, molybdenum concentrate, modified agent

Analysis of the current state of molybdenum mineral and raw material base, mining and processing of molybdenum-containing ores

Molybdenum has a complex of practically significant properties and is widely used for alloying steels and cast irons, in the composition of alloys of various purposes, as well as a structural material in pure form. Molybdenum belongs to the group of rare metals, which causes the relevance of analytical research of the modern state of the mineral- raw material base of molybdenum, extraction and processing of molybdenum-containing ores. The results of analysis of the mineral-raw material base of molybdenum of foreign countries and Russia, assessment of prospects of its expansion are presented. The confirmed world molybdenum resources amount to 12 million tons, including domestic – 2 million tons. 75% of molybdenum reserves are concentrated in the USA, China, Chile, Peru and Canada. Description of the types of deposits of molybdenum, copper-molybdenum and molybdenum-tungsten ores, the main types of molybdenum minerals has been quoted. Methods of ore concentration of various composition for production of molybdenum concentrates, additional enrichment of molybdenum concentrate and industrial practice of molybdenum concentrate processing are considered. In terms of ore quality domestic and foreign raw material base of molybdenum are comparable. 63% of domestic production of molybdenum-containing ores is provided by OJSC “Sorsky GOK”, 33% – OJSC “Zhirekenskiy GOK”. These enterprises produce molybdenum concentrates of grades КМФ-5, КМФ-6, КМФ-7. Their production capacity is about 12 thousand tons of concentrate per year. Molybdenum concentrates are processed by pyro- and hydrometallurgical methods and are an industrial product for production of ferromolybdenum and its chemical compounds. The total capacity of molybdenum concentrate processing plants is 300 thousand tons per year.

Effect of H2O2 on the Separation of Mo-Bi-Containing Ore by Flotation

Hydrogen peroxide (H2O2) is a strong oxidizer that causes non-selective oxidation of sulfide minerals, and its influence on bismuth sulfide ores is not well-documented. In this study, H2O2 was proposed as an alternative bismuthinite depressant, and its effect on a Mo-Bi-containing ore was intensively investigated by batch flotation tests. Results showed that the addition of H2O2 significantly destabilized the froth phase, thus decreasing the solids and water recovery. The recovery of bismuth in molybdenum concentrate was dramatically decreased to 4.64% by H2O2 compared with that in the absence of H2O2 (i.e., 50.14%). The modified first-order kinetic model demonstrated that the flotation rate of molybdenite slightly declined after H2O2 addition, whereas that of bismuthinite was drastically reduced from 0.30 min−1 to 0.08 min−1 under the same condition. Simulation revealed that H2O2 affected the floatability of both molybdenite and bismuthinite but resulted in more detrimental effect to bismuthinite. Hence, H2O2 has the potential to act as an effective depressant in bismuth sulfide ore flotation.