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Variants of processing molybdenite concentrates involving the use of preliminary mechanical activation
Abstract
A review of possible ways to process molybdenite concentrates of various grades by both pyrometallurgical and hydrometallurgical methods is given and the most rational are noted. Prospects for processing low-grade molybdenum raw materials by nitric acid autoclave-less leaching with the complete transfer of molybdenum into the solution in the composition of sulfate complexes is shown. The variant that intensifies the nitric acid leaching of low-grade (6–17% Mo) concentrates obtained by the flotation of ores of the Bugdainskoe deposit via their preliminary dry mechanical activation is suggested.
... 26 Almeida et al. 27 studied the dissolution of chalcopyrite in acid solutions like nitric (HNO 3 ), sulfuric (H 2 SO 4 ), and hydrochloric (HCl) acid using electrochemical impedance spectroscopy (EIS) and found that dissolution of chalcopyrite is controlled by diffusion. 27 Medvedev et al. 28 carried out a series of kinetic studies on leaching molybdenite concentrate by investigating the effect of temperature and nitric acid concentration. Their suggested model has extracted molybdenum from the molybdenite concentrate up to 95%. ...
... The strongest diffraction peak is indexed to the (002) plane of MoS 2 , which means that a large number of grains are in parallel orientation, which is in good agreement with the literature. 25,28,44 The peak at 2q = 14.4°is an indication of the sulphur content of the concentrate. 32,45 The XRD pattern for chalcopyrite in Fig. 1a, as the standard card of JCPDS# 00-035-0752, has peak positions of 29.6°and 58.5°, which correspond to the (112) and (312) crystallographic planes, respectively. ...
In this research, purification of molybdenite concentrate (MoS2) using a nitric acid leaching process was employed for the improvement of molybdenum trioxide morphology during oxidative roasting in an air atmosphere. These experiments were performed using 19 trials designed with response surface methodology and three effective parameters being temperature, time, and acid molarity. It was found that the leaching process reduced the chalcopyrite content in the concentrate by more than 95%. The influence of chalcopyrite elimination and roasting temperature on the morphology and fiber growth of the MoO3 was also investigated by SEM images. Copper plays an important role in controlling the morphology of MoO3 and its decrease led to enhancing the length of quasi-rectangular microfibers from less than 30 μm for impure MoO3 up to several centimeters for purified MoO3.
... The final products of the technology are copper and molybdenum concentrates. The technological scheme for ore processing includes two main operations: collective flotation (main flotation, control flotation, and three refinings) and selective flotation (main flotation, three refinings, and additional flotation of the first refining tailings) [13][14][15][16][17]. Separation of copper-molybdenum concentrates was based on the application of sodium sulphide with preliminary oxidative steaming, kerosene was used as a molybdenite collector [18][19][20][21][22]. ...
This research investigates the hydrometallurgical processing of molybdenum middlings extracted from copper-molybdenum ore at the Shatyrkul-Zhaysan cluster in Kazakhstan. Molybdenum intermediate product obtained after selective flotation of the copper-molybdenum concentrate was used, with 0.07% yield, 22.23% molybdenum content, and 74.91% extraction. Mineralogical analysis shows molybdenite and chalcopyrite as the main minerals. Experiments study atmospheric leaching with nitric acid in single-stage and two-stage countercurrent modes to optimize molybdenum extraction and reduce acid consumption. The optimal conditions obtained were: 300 g/L nitric acid, 100 g/L sulfuric acid, 90?C temperature, and 2 hours leaching time in single stage leaching, giving 98.8% molybdenum extraction. Two-stage leaching under optimized conditions allows obtaining 94.3% molybdenum extraction in solutions with lower residual acidity (0.89 g-eq/L) and redox potential (550 mV) without reducing valuable component extractions. Molybdenum extraction reaches 94.3% in the subsequent solvent extraction stage from two-stage leaching solutions. The final product, calcium molybdate containing 46.83% molybdenum, meets commercial grade specifications. This research demonstrates an effective process for the hydrometallurgical production of commercial calcium molybdenite from copper-molybdenum ore, with high molybdenum recovery, reduced acid consumption through two-stage leaching, and minimal hazardous discharges.
... It is well-known that sodium sulphate can be obtained as a result of NaCl interacting with iron pyrite ore (Maslenitskiy, 1987), chalcopyrite ore (Charkavortty and Srikanth, 2000), and copper sulphides Medvedev and Alexandrov, 2012). Thus, according to some studies (Rajic and Zlatanovic, 1988), the application of X-ray testing methods fail to identify sodium sulphate among the solid interaction products of molybdenite and sodium chloride. ...
The low-temperature calcination of nickel sulphide concentrates with sodium chloride and subsequent hydrometallurgical processing is a promising alternative methods. This study aims to identify the interaction products of sulphide nickel concentrate components with sodium chloride at temperatures of 400–450 °C. Thermodynamic studies have demonstrated that nickel sulphates, chlorides, and oxides are the probable nickel-containing products of the interaction between nickel sulphide and sodium chloride in the presence of oxygen. At 350–450 °C, the formation of nickel sulphate is preferred; as the temperature increases, the probability of oxide formation also increases. We experimentally confirmed that nickel sulphate is the main nickel-containing product of the reaction between nickel sulphide concentrate and sodium chloride at 400 °C, and the reduced nickel oxide and chloride content was identified in the calcine. The other main products included iron oxide (III) and sodium sulphate. During calcination at 400 °C, up to 75% of the sulphur contained in the concentrate was bound to sodium sulphate.
A hydroxylated xanthate salt (HXS) was synthesized from ethanol, carbon disulfide, and NaOH. The flotation responses of chalcopyrite and molybdenite when HXS was used as a novel depressant were investigated using bench-scale flotation tests. The bench-scale flotation results indicate that HXS strongly influenced the flotation of chalcopyrite and had little effect on the flotation of molybdenite. These results can be attributed to a significant improvement in the molybdenite/chalcopyrite selectivity surface index after the addition of HXS. The synthesized HXS contained both solid-philic and hydrophilic groups. The molybdenum recovery achieved using HXS was 9.91% higher than that obtained using sodium hydrosulfide, and better separation was achieved. Compared with sodium hydrosulfite, the chemical oxygen demand, sulfates and five-day BOD decreased significantly using the alternative depressant. This HXS is therefore a potential depressant for use in copper-molybdenum separation.
The availability of applying oxidizing-chlorinating roasting with alkali metal chlorides to process the molybdenite concentrate, which is determined by a decrease in roasting temperature to 450°C and the formation of water-soluble molybdenum compounds during roasting, is shown. It is established that ∼60–75% molybdenum remains in ash in this case, while its remaining amount is chlorinated and distilled in the composition of chlorides and oxychlorides being completely caught in the settling chamber and absorbers. The chemism of processes occurring during the oxidizing-chlorinating roasting, which makes it possible to explain a decrease in the oxidizing temperature of molybdenite from 550–600 to 450°C, is described. Optimal modes of ash leaching with water and alkali solutions are determined; based on them, a functional production flowchart which includes oxidizing-chlorinating roasting with sodium chloride, two-stage leaching (aqueous and alkaline), and the dissolution of condensed molybdenum oxides and oxychlorides, is proposed to process molybdenite concentrates. This flowchart makes it possible to process certified molybdenite concentrates with the recovery of molybdenum into solutions no lower than 98%.
Methods of trapping nitrous gases (NOx
), which evolve during the nitric acidic decomposition of sulfide minerals, are reviewed and the advantages and disadvantages of each of them are given. The results of experiments on the adsorption of NOx
with water are presented. The dependences that the degree of catching NOx
has on different factors such as water temperature, its column height, gas dispersion, and oxidizer (oxygen air) consumption are revealed. It is established that, in order to increase the efficiency of trapping nitrous gases, it is recommended that, after they finish bubbling through water, the solutions be held for 2–3 days in hermetic vessels under a low excess air pressure. It is shown that the absorption of NOx
with water takes place more efficiently on the phase interface than inside the bulk.
Investigations on processing the low-grade molybdenite concentrate of the Bugdainskoe deposit by the nitric-acid method are
carried out. The leaching modes (S: L ratio, reagent concentration, process duration, and temperature) are optimized. In optimal
modes, the recovery of molybdenum from the starting concentrate into the solution exceeds 95%. The penetrating recovery from
the ore into the commercial product is at a level of 85–86%. Investigating the process kinetics showed that the decomposition
of the concentrate by nitric acid proceeds in the initial point in time in the kinetic mode. The addition of sulfuric acid
into the nitric acid solution accelerates the process.
The scientific theoretical prerequisites for the use of small additives of nitric acid for the intensification of the autoclave
oxidative leaching (AOL) of sulfide concentrates are checked in order to increase the degree of extraction of the base metal
with a simultaneous decrease in the cost of the process. The technological parameters of the AOL conditions applied to molybdenite
are also refined, and recommendations for a practical application of the apparatus of the process and for a decrease in its
cost are made.
Metallurgiya tugoplavkikh redkikh metallov (Metallurgy of Refractory Rare Metals)
- A N Zelikman
Prevrashcheniya sul’fidov pri aktivatsii (Transformations of Sulfides during Activation)
- V G Kulebakin
- V.G. Kulebakin
Eksperimental’nye metody v mekhanokhimii tverdykh neorganicheskikh veshchestv (Experimental Methods in Mechanical Chemistry of Inorganic Substances)
- V V Boldyrev
- V.V. Boldyrev
in Trudy nauchno-prakticheskogo seminara “Nauchnoe obespechenie innovatsionnoi deyatel’nosti predpriyatii, institutov i firm v metallurgii
- A S Medvedev
- A.S. Medvedev
Vyshchelachivanie i sposoby ego intensifikatsii (Leaching and Methods for Its Intensification)
- A S Medvedev
- A.S. Medvedev