International Journal of Mineral Processing最新文献

A protocol based on peroxide fusion has been developed for the determination of Au in metallurgical samples and ores covering a wide range of concentrations and diverse mineralogies. The quantity of Na₂O₂ required was minimised, while maintaining lixiviant efficacy, by the use of mixed NaOH + Na₂O₂ fluxes. The method was shown to be particularly applicable to the determination of coarsely-particulate gold. Fusion cakes were dissolved in hydrochloric acid and then extracted using methylisobutylketone to provide concentrations appropriate for quantification by graphite furnace atomic absorption spectroscopy and to minimise interferences from dissolved salts. The protocol was tested on a variety of certified reference materials and produced results in excellent agreement (at Au concentrations ranging from 0.05 to 47 μg g^− 1) with the traditional lead fire assay method, while avoiding the health and safety issues associated with that technique.

A cationic organic silicone surfactant (DTA) with specially designed functional groups was developed as a flotation collector for smithsonite. This surfactant was synthesized via the reaction between hexaethyldisiloxane and N-β-(aminoethyl)-γ-aminoisobutylmethyldimethoxy silane using tetramethylammonium hydroxide as a catalyst. Its flotation performance was validated by flotation tests using pure minerals. The results illustrated that DTA has strong collecting ability and better selectivity for smithsonite against quartz, calcite and dolomite compared to the traditional collectors such as octadecylamine, tetradecylamine and dodecylamine. Based on the analysis of FTIR spectra, zeta-potential measurements, X-ray photoelectron spectroscopy and density functional theory calculations, it can be concluded that the adsorption mechanism of DTA on the surface of smithsonite was mainly dominated by chemisorption and electrostatic adsorption. DTA's unique properties, which include two coordination sites (NH₂ and NH), and the “parachute” shape structure of OSi(C₂H₅)₃, resulted in superior collecting powers for smithsonite.

The wear problem on the internal lining of bins and chutes needs to be addressed before any significant efficiency gains during iron ore mining operations. This study aims to investigate the factors determining the wear resistance of common lining materials used in iron ore mining operations. A purposely designed experimental system was utilised to quantitatively assess the wear resistance of a suite of wall lining materials against an iron ore abrading medium, from which a wear rate for each liner is determined. Results suggested that the hardness of a lining material can be utilised to indicate its abrasion wear resistance. From experimental results, prediction models of the service life of selected lining materials in bins and chutes are also obtained.

This study investigates the influence of ethylene-vinyl acetate/vinyl ester of versatic acid (EVA/VE), a redispersible polymer powder, on the mechanical, chemical, and microstructural properties of sulfidic and non-sulfidic cemented paste backfill (CPB). Different EVA/VE amounts (7.5 to 20 wt% of cement mass) are examined in CPB mixtures. To assess the influence of EVA/VE on the CPBs consistency (fresh state), slump height was measured using a small Abram's cone. Uniaxial compressive strength (UCS) testing was conducted to determine the influence of polymer powder on the mechanical strength development of CPBs, and mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and differential thermogravimetric analysis (DTG) were used to determine the influence of polymer powder on the microstructure and mineralogy of hardened CPBs. The achieved results implicated the dependency of polymer powder effectiveness on the tailings type. Of the different polymer powder proportions used in this study, the addition of 15% EVA/VE (based on the mass of binder) was only effective in improving UCS values of sulfidic tailings. The MIP, DTG, and SEM results also indicate that the addition of 15% polymer powder was beneficial for chemical and microstructural improvement of sulfidic CPBs only.

In this paper, the influence of 2-ethylhexanol used as a modifier/emulsifier on the surface chemical property of low rank coal and its flotation performance was investigated. According to the FTIR analysis, it showed an obvious decline in the hydrophilic groups while an increase in the hydrophobic groups on the surface of coal after pretreatment by 2-ethylhexanol solution for 12 h, resulting in the increase of contact angle from 74.9° to 95.4°. Whereas the induction time showed a significant decrease from 246.0 ms down to 85.4 ms, which meant the better hydrophobicity and floatability of coal particles after the pretreatment. As a result, a better flotation efficiency of low rank coal was attained after the pretreatment. Additionally, the oily bubble flotation combining 2-ethylhexanol was employed to enhance the flotation of coal samples. The results indicated that the mixture of diesel oil and 2-ethylhexanol improved the collecting power and selectivity of oily bubbles, with the oil contact angle for coal samples decreasing from 17.8° to 14.5° and the induction time from 50 ms down to 19.7 ms. The performance of oily bubble flotation, especially using the mixed diesel oil bubbles, was much better than that of conventional flotation, and the recovery of combustible matter and flotation efficiency index increased from 43.42% and 29.52% up to 89.27% and 59.91% respectively. Consequently, the flotation performance of low rank coal may be enhanced by the surface modification of 2-ethylhexanol as well as the novel oily bubble flotation technology.

The collecting ability of dodecylamine (DDA) and dodecyltrimethylammonium chloride (DTAC) as two cationic collectors was investigated in the flotation of pyrolusite and calcite by carrying out the flotation experiments, FTIR analysis, zeta potential tests and contact angle measurements. The single mineral flotation experiments show that the maximum differences between the floatability of pyrolusite and calcite occurring at a pH of 7.5 in the presence of DTAC is more than that of DDA. This means that DTAC acts more selectively than the DDA collector. In the microflotation experiments carried out on the artificially mixed minerals, the MnO content and recovery in the pyrolusite concentrate obtained by DDA collector is greater than that achieved by DTAC. As evidenced by ore flotation results and contact angle measurements, in the presence of both collectors, sodium carbonate acts more effective than calcium chloride as calcite depressant agents. In the ore flotation experiments, a pyrolusite concentrate containing higher MnO grade and recovery is obtained using DDA collector in comparison with DTAC. These results indicate that the collecting power of DDA is significantly more than DTAC collector. FTIR analysis and zeta potential tests show that both collectors adsorb on the surface of pyrolusite and calcite through the electrostatic interactions. Also, these analyses indicate that the adsorption of DDA on the surface of both minerals is greater and stronger than that of the DTAC collector.

In this paper, a novel process was studied for the recovery of iron and titanium from ilmenite concentrate. The ilmenite powders first underwent an oxidation pretreatment and were reduced isothermally at 1350–1450 °C by graphite with the addition of Na₂SO₄. The influence of temperature, C/O molar ratio and the dosage of the added Na₂SO₄ on the metallization ratio, phase transformation and titanium grade were studied. The results demonstrated that Na₂SO₄ not only significantly promotes the aggregation and growth of metallic iron-grain particles but also enhances the reduction ability. Under the promotion of added Na₂SO₄, the highest metallization ratio reached 94%, and the theoretical calculation of the highest grade of titanium dioxide is approximately 75%. The Na₂SO₄ additive decreases the melting point of the slag and metal, resulting in the effect of semi-melting reduction. The carbothermic reduction order of phase transitions of pre-oxidized ilmenite concentrate was also discussed.

The diminishing availability of nickel sulfide ores and the increasing demand for nickel and its compounds have led to a growing interest in laterite deposits as an alternative source for producing nickel. However, extracting nickel from laterite ores differs from sulfides because nickel contained minerals are generally disseminated throughout the ore. Laterites cannot be concentrated using classic mineral processing techniques such as flotation.

The present study proposes a new smelting process for limonitic nickeliferous laterite ore in order to separate nickel and cobalt from the ore and produce a nickel matte at lower smelting temperature compared with the current industrial techniques. The nickel and cobalt recoveries were evaluated at various flux additions. The highest recovery condition for Ni (98% Ni recovery with Ni content of 10 wt%) was achieved with the addition of 27 g of flux (50%Na₂CO₃ + 35%Na₂B₄O₇·10H₂O + 15%SiO₂), 0.8 g coke and 5 g elemental sulfur to 25 g of the roasted ore. The above conditions led to achieving 95% Co recovery with 0.06% Co.

Substantial progresses have been made over the past decade in using machine vision for automatic control of the froth flotation process. A machine vision system is able to extract the visual features from the captured froth images and present the results to process control systems. The current research work is concerned with the development and implementation of a machine vision system for real time monitoring and control of a batch flotation system. The proposed model-based control system comprises two in-series models connecting the process variables to the froth features and the metallurgical parameters along with a stabilizing fuzzy controller. The results indicate the developed machine vision based control system is able to accurately predict the metallurgical parameters of the existing batch flotation system from the extracted froth features and efficiently maintain them at their set-points despite step disturbances in the process variables. Furthermore, the proposed control system leads to higher target values for the metallurgical parameters than the previously developed system (R_Cu = 91.1 % ; G_Cu = 11.2% vs. R_Cu = 87.6 % ; G_Cu = 8.1%).

The hydrophilicity is an important parameter in characterizing the floatability of coals in floatation. To quantify the hydrophilicity, the quantum chemistry calculation was used to calculate the hydrogen bonding energies in the wetting process by DFT B3LYP 6-31G. It is known that the floatability of lignite is much lower than that of the high-volatile bituminous coal from the natural floatability test. Besides, the hydrophilic sites were mainly oxygen functional groups. From XPS results, it is indicated that there were four kinds of oxygen functional groups, including OH, CO, CO and COOH in lignite, while there were three kinds of oxygen functional groups, containing OH, CO and CO in the high-volatile bituminous coal. On the other hand, the simulation results showed that the hydrogen bonding energy of these hydrophilic sites are in the following order − COOH > − OH > C − O > C = O. The released hydrogen-bonding energies were calculated to be 2.36 kcal/mol for lignite and 1.31 kcal/mol for high-volatile bituminous coal, respectively. In addition, the calorimetric experiments also showed that the wetting heats were 105.37 J/g (lignite) and 47.00 J/g (high-volatile bituminous coal). The hydrogen bond energy distribution of each hydrophilic sites showed that all the four kind hydrophilic sites impacted the lignite hydrophilicity remarkably whereas only OH and CO affected the hydrophilicity of high-volatile bituminous coal. It was revealed that the difficulty in lignite flotation was dominated by the complex contribution to hydrophilicity of the oxygen functional groups.