Comparative study of mechanical activation of molybdenite (MoS2) with and without magnesium (Mg) addition

Molybdenite concentrate was mechanically activated in the presence of magnesium metal using a planetary mill in order to try to form elemental molybdenum. A sample milled for 90 min in planetary mill showed almost the same structural distortion as after 50 h in a tumbling mill, neither showed the presence of molybdenum metal. However, molybdenite milled together with magnesium showed more amorphization than separately milled molybdenite. Despite the apparent lack of reaction, molybdenite showed higher solubility in dilute HCl after milling with magnesium than without.Mongolian Journal of Chemistry 16 (42), 2015, 30-3

Enhancing oxygen recovery from ilmenite by extended milling

The generally accepted method for recovering oxygen on an extraterrestrial body is by thermally induced reduction of indigenous minerals by hydrogen. The most amenable mineral is considered to be ilmenite, FeTiO3. The effect of up to 400 h ball milling on the subsequent hydrogen reduction of a terrestrial beach sand derived ilmenite is examined. XRD examination of the final powders indicates that reduction of ilmenite proceeds via elemental iron and rutile which is then further reduced to sub-oxides. The recovery of oxygen as water was found to be over two and a half times greater for a sample milled for 400 h than for an unmilled sample

New route for the extraction of crude zirconia from Zircon

A commercial grade of zircon (ZrSiO4) concentrate was mechanically milled with MgO for up to 100 h in a laboratory-scale mill. The resultant powders were subjected to thermal processing, chemical leaching, and X-ray diffraction (XRD). There was no direct evidence of reaction during the milling step, with no new phases evident from XRD. Leaching of the powder showed that a reaction had occurred, and increased solubility with milling time was attributed to the formation of a nanostructured Mg-Zr-Si oxide, which dissolved congruently. Heating the powders resulted in a number of thermal events, including the formation/crystallization of ZrO2 and Mg2SiO4. Thermal treatment of the milled powders allowed selective chemical leaching of the magnesium and silicon, leaving a powder containing ∼90% ZrO2

Activation of the carbothermic reduction of manganese ore

The effect of extended milling on the carbothermic reduction of a manganese ore has been examined using a combination of thermal analysis and X-ray diffraction (XRD). Thermodynamic modelling indicated that reduction of MnO2 to MnO was possible at 25 °C, although no reaction was found to occur during milling of the ore with graphite for up to 10 h. For a physical mixture, cryptomelane, KMn8O16, reduced at 500 °C and braunite, Mn7SiO12, at 700 °C after 10 h milling these temperatures were reduced by 200 °C. The initial product was Mn3O4, although in the 10-h-milled powder, the reduction of braunite may have been directly to MnO. Reduction at 600 °C only formed Mn3O4 in the unmilled powder but the major product in the 10-h-milled powder was MnO. The increased extent of reaction after premilling may allow current processing plants to expand their throughput without increasing the size of reduction kiln

Highly adsorbent carbon formed by ball milling

The adsorption capacity of activated carbon formed by ball milling from alumina and synthetic graphite was investigated. It was observed that ball milling graphite with a harder phase led to a greater adsorption capacity for a shorter milling time. The mass loss of the sample was found to be a function of temperature. The mass losses during leaching were 9.75% and 25.2% for graphite milled for 50 h without and with alumina respectively. Compared with graphite milled alone, the sample milled with alumina has a capacity of 3.7 time greater

The Intec copper process: A detailed environmental analysis

The Intec Copper Process is an environmentally advantageous hydrometallurgical process for the production of high purity copper and associated precious metals from copper sulphide concentrates. The process uses a mixed chloride-bromide lixiviant in an elegant cyclic circuit to leach the copper into solution, rejecting the iron as stable hematite rather than as unstable jarosite. After purification of the pregnant liquor, copper is electrowon at London Metal Exchange Grade A purity, while the anodic energy of the cell is stored as the soluble species, Halex TM , for recycle as the regenerated lixiviant to the leach circuit. Both gold and silver are leached and recovered directly from this cyclic process without resorting to cyanide leaching of the residue. No liquid emissions result from the Intec Copper Process, whilst spent air and water vapour from the leach are released to the atmosphere. The sulphur in the minerals reports to the solids residue in elemental form, without the need for expensive handling of voluminous gaseous sulphur dioxide streams found in smelters. A significant difference to competing smelting and hydrometallurgical processes is that any mercury entering the process from the sulphide concentrate feed is recovered rather than reporting directly to waste or polluting the environment. Outside the process circuit itself, the Intec Copper Process has several notable environmental advantages over competing technologies: 1. Flexibility of scale with low capital and operating costs allow operation directly at the mill head at production rates as low as 15 000 tpa, significantly reducing environmental impacts from concentrates transport. 2. The ability to handle low-grade and dirty concentrates often allows greater recoveries in the mill, improving both the economics and environmental acceptability of a mine by reducing metal losses to tailings. 3. A comparison of the total energy requirements of the Intec Copper Process with those of competing technologies shows that the Intec Copper Process has the lowest energy consumption of any of the known hydrometallurgical processes, as well as improving upon pyrometallurgy under appropriate conditions

Secondary school science teachers as the key to a sustainable workforce in the mining and mineral processing industry - Changing people's attitudes

This paper reports on an innovative professional development program for school science teachers run collaboratively between the Centre for Sustainable Resource Processing and Murdoch University. Ultimately the initiative aims at increasing the pool of school students with strong science and mathematics backgrounds while highlighting the challenging careers available in the mineral resource sector including the gold industry. The program is unique in that it seeks to develop a network of science teachers who may participate in a series of workshops, short courses and tours over several years. The objective is to raise secondary school students' awareness of potential careers within the minerals sector by exposing teachers to a real life, hands-on look into the mining and minerals resource industry. Though the program includes the breadth of the resource processing sector, the potential value to gold processing is in developing a greater pool of potential employees. The initiative allows teachers to develop a better insight into the practical applications of the theoretical sciences they are required to teach. The evolution of the program from the first trials with Western Australian teachers to the introduction of the initiative to Queensland teachers are reported on. Additionally, the results of a pilot study involving 40 participating teachers are described. This study used a questionnaire and follow-up interviews to gain quantitative and qualitative feedback from teachers. There is evidence that the professional development program has resulted in teachers acquiring a new found appreciation for the application of the fundamental chemistry and physics they teach within the school curriculum. Also reported are associations between teacher participation in this professional development program and changing attitudes towards the industry in a positive way. Finally, there is some indication that these positive teacher attitudes may result in their students developing a better understanding of the diversity and availability of career paths within this industry

Oxidation of chalcopyrite by extended milling

Chalcopyrite has been milled for up to 50 h in oxygen, air and argon atmospheres using a laboratory ball mill. No phase changes were evident in argon but the XRD peaks were weaker and broader indicating crystalline refinement. In oxygen, even after 1 h milling peaks for CuSO4•5H2O were present and these became predominant after 20 h milling where the chalcopyrite peaks were absent. In air, partial oxidation to CuSO 4•5H2O was evident after 50 h. Leaching of the resultant powders with water showed 80% dissolution after 50 h milling in oxygen, significantly greater than the 20% and 6% dissolution after milling for 50 h in air and argon respectively. Solution analyses showed the Cu/Fe ratio increased with milling time in oxygen suggesting selectivity may be possible. The insoluble residue was found to consist of haematite, elemental sulphur and unreacted chalcopyrite

Effect of milling in oxygen on sphalerite-bearing materials

A sphalerite concentrate and two flotation rougher tails have been milled in an oxygen atmosphere for up to 10 h. Pressure measurements on the mills indicated that the concentrate had an induction time of < 2 h before significant reaction occurred whereas one of the tailings showed reaction within 1 h. The second tailings sample showed a slow pressure loss with time. All three samples showed a similar rate of pressure loss between 2 h and 10 h of milling indicating they were probably all reacting at a similar rate. Leaching of the milled powders in water showed significant increases which coincided with the pressure drops indicating that the oxidation products were water soluble; similar increases were also evident in acid

Formation of an alumina–silicon carbide nanocomposite

The high intensity ball milling of a mixture of silicon dioxide, aluminum and graphite powders was investigated to determine the formation of a composite of alumina and silicon carbide. Differential thermal analysis (DTA) was performed on milled powders. The products were analyzed by x-ray diffraction using monochromatic Cokα radiation using acount time of 1 s per 0.03 °step. The results show that for shorter milling time the reaction was two stage with elemental silicon appearing as an intermediate prior to carburization to silicon carbide