International Journal of Mineral Processing最新文献

The study presents an evaluation of the possibility of using Class C fly ash for the synthesis of faujasite (Type X) and tschernichite (Type A) type zeolite materials. In order to obtain the well-formed zeolites, syntheses were carried out. The variables were: the ratio of NaOH to fly ash, water, the filtrate (post-reaction solutions obtained during the hydrothermal synthesis of zeolites rich in Si), and the amount of added aluminium foil. The analysis showed that three of the most effective reactions (from which Samples 21–23 were derived) occurred under the following conditions: the ratio of NaOH/fly ash was 1.6, 2.0 and 1.25, respectively, with a fusion temperature of 550 °C (for each of the three reactions), fusion time of 1 h and reaction time of 4 h (for each of the three reactions); the amount of H₂O was 100, 100 and 50 ml; the amount of filtrate was 0, 0 and 50 ml; the amount of added aluminium foil was 0.5 g (for each of the three reactions); and the reaction temperature was 80 °C (for each of the three reactions). The three best zeolite materials (Samples 21–23) that were derived were subjected to mineralogical (X-ray powder diffraction [XRD], scanning electron microscopy-energy-dispersive X-ray spectroscopy [SEM-EDS]) and chemical (X-ray fluorescence [XRF]) characterization, with the addition of textural analysis (Brunauer-Emmett-Teller [BET] specific surface area and pore volume and size). Studies have shown that the obtained zeolites have a Type A (Samples 21–22) and Type X (Sample 23) structure, including well-formed grains with isometric and cubic characteristics. The calculated unit cell parameters of the obtained zeolites indicate a cubic crystal system and are very close to the reference values for structures of X and A type zeolites. The ratio of SiO₂/Al₂O₃ in each of the three tested zeolite materials was as follows: 2.16, 1.98 and 2.41. The specific surface area amounted to 106, 104 and 256 m²/g for Samples 21–23, respectively. Obtained results were similar to the type of zeolite structures obtained from Class F fly ash. Therefore, we can conclude that the analysed Class C fly ash may also be a productive substrate for the synthesis of zeolite materials of Type X and A.

It is possible to analyze in situ the adsorbate/adsorbant interaction during the flotation process by high frequency dielectric measurements. The adsorption of complexing collector (sodium oleate) onto calcite increases the dielectric permittivity independently of the frequency. The dielectric constant increases after adsorption because the adsorbate and the adsorbant interact through covalent bonds. Physical adsorption involving electrostatic interactions or hydrogen bonds (dodecylamine and dodecylsulfate) has no effect on the dielectrical characteristics. The dielectric method allows to analyze the mechanisms of depression using reagents such as quebracho and sodium silicate.

The flotation behavior of ilmenite and titanaugite using anionic collector sodium oleate (NaOL), cationic collector dodecylamine acetate (DAA) and the mixed anionic/cationic collector (NaOL-DAA) was investigated through micro-flotation experiments, zeta potential measurements, Fourier transform infrared (FTIR) analyses, and the artificially mixed minerals flotation experiments. The results of the microflotation experiments indicate that DAA exhibits good flotation performance to both ilmenite and titanaugite at a pH > 6.0. The flotation separation of ilmenite from titanaugite can be performed using the mixed NaOL-DAA in a wide pH range of 5.0–7.0. In this pH range, the recovery of ilmenite remains constant at approximately 90%, while the recovery of titanaugite remains < 25%. The best separation result can be achieved with NaOL-DAA molar ratios of 10:1. The results of the zeta potential experiments and the FTIR analyses indicate that the adsorption of the mixed collector, NaOL-DAA, on the ilmenite surface is larger than on the titanaugite surface and that the NaOL-DAA complex might be mainly adsorbed on the ilmenite surface by chemical adsorption, apart from electrostatic adsorption. The synthetic mineral mixture micro-flotation results demonstrate that, compared to NaOL, NaOL-DAA not only increases the recovery and grade of the TiO₂ by 7.02% and 6.71%, respectively, but also decreases the reagent consumption by half.

To date, the quest for cost-effective methods for removal of dissolved metals from aqueous solutions remains a daunting challenge for many industries. This paper reports on the development of an effective, hybrid adsorbent for selective copper recovery from aqueous solutions under industrially relevant conditions. The work involved (i) purification and functionalization of diatomaceous earth (DE) particles with glutaraldehyde(GA)-crosslinked polyethyleneimine(PEI), (ii) physicochemical characterization of the product and (iii) metal adsorption from solutions containing Cu(II)/Ni(II)/Fe(II)/Ca(II)/Mg(II)/Mn(II)/Al(III)/Na ions and their subsequent elution behaviour. Acid leaching of the pristine DE led to a significant reduction in its metal oxide (e.g., Al₂O₃, Fe₂O₃) constituents and a concomitant increase in both SiO₂ content and specific surface area. Upon functionalization with GA-crosslinked PEI, the DE particles' interfacial chemistry was completely altered to that of the polymer with no change in specific surface area. Isothermal batch adsorption from saline (15 g/dm³ NaCl) and non-saline solutions containing 500 and 1000 mg/dm³ of Cu at ~ pH 4 revealed > 97% Cu(II) removal by functionalized DE within 3 min in both cases. Subsequent water elution tests at pH 1 showed complete release of the adsorbed Cu confirming pH-dependent interaction between dissolved Cu and GA-crosslinked PEI. The preliminary batch adsorption/elution tests involving 1000 mg/dm³ solutions of Ni, Ca, Mg, Mn, Fe, Na and Al showed little or negligible affinity of the functionalized DE towards these elements, suggesting good selectivity for Cu. Furthermore, it is shown that the functionalized particles are chemically stable at H₂SO₄ concentrations up to 2 M and may be recycled > 10 times without loss in their Cu adsorption/desorption performance.

In this research, a numerical approach and a series of laboratory tests have been used to investigate the effect of vertical baffling and height to diameter ratio on the axial mixing in flotation columns. The baffle is a plate located perpendicular to the cross section of the column with a length of 2.8 m and thickness of 0.4 cm. The computational domain is a column with a circular cross section having a height of 3.2 m and a diameter of 10 cm. Three-dimensional simulations were executed using Eulerian two-phase computational fluid dynamics (CFD) models for both non-baffled and baffled columns. In order to reduce computing demand and simplify the problem, it was assumed that the column is already filled with water, and air enters from the lateral and upper surfaces of a cylindrical sparger with a length of 15 cm and a diameter of 1 cm located vertically at the bottom of the column. To validate the simulation results, a series of laboratory flotation column experiments have been performed under the above-mentioned conditions. Three-dimensional simulations were executed using an Eulerian two-phase model for both non-baffled and baffled columns. The simulated pressure values on the wall at 0.2 m and 2.8 m height of the non-baffled column were in good agreement with experimentally measured values with the highest relative difference of < 3.07%. Comparison of the computational results for the non-baffled and baffled columns showed that baffling can reduce water axial velocity up to 16.96%, which consequently reduces the axial mixing in the column and increases flotation recovery. Study of the effects of height to diameter ratio showed that effect of baffling in columns with lower aspect ratios is more prevalent for reducing the axial mixing.

The preconcentration or early rejection of gangue minerals in mineral processing operations is investigated using sorting, based on interpretation of near infrared sensor data collected from ore particles. The success of sorting depends on the distribution of minerals between particles, the arrangement or association of minerals within particles and the ability of near infrared to distinguish relevant minerals. This paper considers minerals association, using common alteration minerals found in a hydrothermally-formed copper ore, with sensitivity in the near infrared region. The selected NIR-active minerals were arranged along the view of NIR line scanner to stimulate adjacent natural minerals association.

It was found that spectral dominance may depend on minerals near infrared sensitivity and or the position of a mineral along the NIR scanner line of view. Analysis also revealed that only free occurring waste mineral spectra can be targeted for discrimination as tailings. Where spectra appeared mixed, such spectra are best considered products.

There is little in-depth study on the downstream processing characteristics of granulated PGM-containing converter matte, particularly related to grinding and liberation behavior closely associated with leaching, and also as a function of iron endpoint specific mineralogy. Moreover, there is limited physical property data available, such as hardness and breakage of converter matte mineral structures that allows for considering a possible dependence between the mineralogy and the downstream processing characteristics of converter matte. The aim of this study was to investigate a relationship between indentation hardness, breakage and the mineralogy of two different iron end point converter mattes namely Fe_0.15% and Fe_5.17%. This also allowed for a subsequent investigation to relate the mineralogy to the integrated downstream processing characteristics of granulated converter matte.

A Nano-indentation tester was used to measure the indentation hardness of mineral structures. The indentation system also had the ability to test the breakage characteristics of the respective mineral structures by applying a preset load. Laboratory batch grinding tests were conducted at various specific energies with respect to granulated high and low iron mattes. A high resolution field-emission scanning electron microscope was utilized for mineralogical analysis. The perfect mixing ball mill model was subsequently used to assess the breakage rates of matte particles and minerals. A mineral liberation analyzer was used to investigate the liberation characteristics of mineral structures of interest.

The investigations revealed that the minerals and associated boundaries showed relatively different indentation hardness. The indentation-induced breakage of nickel sulfide, copper sulfide and NiCu-alloy structures appeared preferential and related to the iron end point. The softest mineral was found to be copper sulfide, which exhibited the average indentation hardness of 1975 and 2978 MPa within the low and high iron matte respectively. The increasingly harder minerals were nickel sulfide and NiCu-alloy in both low and high iron mattes with mean values around 5000 MPa. The laboratory batch grinding of the converter mattes at specific energy inputs resulted in product size distributions correlated to the underlying mineralogy. Although the trends for the breakage rates was found to be similar for both mattes, the matte with Fe content of 5.17% exhibited higher breakage rates in the specific energy ranges from 5 kWh/t to 25 kWh/t. This indicated that the matte with 5.17% Fe produces finer product than that of the 0.15% Fe matte at the same energy level. Moreover, a higher degree of overall liberation was achieved for copper sulfide and NiCu-alloy present within the high iron matte particles compared to particles within the low iron matte. 40% of particles within the high iron matte are comple