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By L. L. Chasko, D. W. Alexander

Researchers from the National Institute for Occupational Safety and Health’s Office of Mine Safety and Health Research conducted an assessment of the effects that ground control mesh might have on rock and float coal dust distribution in a coal mine. The increased use of mesh to control roof and rib spall introduces additional elevated surfaces on which rock or coal dust can collect. It is possible to increase the potential for dust explosion propagation if any float coal dust is not adequately inerted. In addition, the mesh may interfere with the collection of representative dust samples when using the pan-and-brush sampling method developed by the U.S. Bureau of Mines and used by the Mine Safety and Health Administration for band sampling. This study estimates the additional coal or rock dust that could accumulate on mesh and develops a means to collect representative dust samples from meshed entries.

Jan 1, 2014

By Wantae Kim, Hoon Lee, Kwanho Kim, Sangbae Kim

Mechanochemical activation of starting minerals and their effect on the solid-phase synthesis and properties of ceramics with lower thermal expansion coefficient was examined. The mineral mixture, pyrophyllite-gibbsite-lithium carbonate, was prepared for the synthesis of ?-eucryptite (Li2O•Al2O3•2SiO2). Dry grinding using a planetary ball mill promoted the amorphization of the starting mixtures. XRD and FT-IR results showed that the crystallization of the target materials occurred from the ground mixtures by calcination. The crystallization of them increased with increment of grinding time and calcination temperature. In the synthesis, the trace of undesired phases such as quartz and cristobalite once formed during calcination at the temperature range from 750 to 850 °C almost disappeared and monophase ?-eucryptite was formed in the ground mixture at 950 °C. The lowest liner thermal expansion coefficient (TEC) of ?-eucryptite prepared was -2.5x10-6•°C-1. The thermal expansion behavior characteristics of the calcined

Jan 1, 2014

By Rong Fan, Andrea Gerson

"The small recovery of Ag, often in the order of 50%, by traditional flotation and leaching process strategies is closely related to the complicated and heterogeneous nature of Ag-bearing minerals with Ag typically being associated with numerous minerals within any given ore-body. Moreover, grain sizes may be extremely fine with micron-scale common. In order to design cost-effective Ag-bearing mineral flotation and leach recovery strategies it is firstly necessary to characterise the speciation of Ag and its correlation with other elements, e.g., Cu, As and Sb, within the ore matrix and process streams. The traditional QEM-SCAN analytical approach can prove problematic for some mineralogies due to difficulties in recognising degrees of crystallinity, polymorphs, complex solid solution series, high value trace element mineralogy, very fine grained materials; and the requirement for a comprehensive data base. Moreover, there is difficulty ‘seeing’ either surface films or surface contaminants which can both lead to poor flotation performance. There is therefore clearly a need to develop confirmatory and complementary approaches when these uncertainties arise. Synchrotron X-ray microprobe analysis provides a powerful tool for the mineralogical characterisation of finely segregated heterogeneous Ag-containing materials. These measurements enable comprehensive characterisation of the Ag-bearing components using synchrotron microprobe X-ray fluorescence mapping (µ-XFM), X-ray diffraction (µ-XRD) and X-ray absorption spectroscopy (µ-XAS). Further analytical strength is provided by principal component analysis of laboratory ToF-SIMS data which enables the statistical identification of correlated surface species enabling examination of surface chemical characteristics responsible for mis-reporting of Ag containing components within flotation streams. We describe the application of these techniques to a selected Ag-containing feed and tail and demonstrate how these compliment and extend traditional analytical methodologies."

Jan 1, 2014

By B. H. Zhao

A low grade Pt-Pd ores, with 1g/t Pt and 0.13g/t Pd, and 8.70% Fe and 2.50% P2O5 is experimented to recover of Pt and Pd. The flowsheet is proposed which consists of Pt-Pd selective flotation, apatite flotation from tailings of Pt-Pd flotation, magnetic separation of magnetite from apatite flotation tailing. With butyl xanthate, N-ally group-O-isobuturyl-thioanimoformate and Sodium y-89 xanthate as collectors, sodium silicate as depressant, and sodium carbonate as pH regulator, a concentrate, assaying 324.52 g/t Pt and 45.62 g/t Pd, is obtained with recoveries of 87.23% Pt and 76.89% Pd from surface ore. A concentrate, assaying 1693.53 g/t Pt and 64.12 g/t Pd, is obtained with recoveries of 88.54% Pt and 83.78% Pd from primary ore. At same time, A iron concentrate assaying 64.12% Fe with a recovery of 24.94%, and a apatite concentrate assying 30.32% P2O5 with a recovery of 80.12% are obtained.

Jan 1, 2014

By Sergio Castro, Janusz Laskowski

In the flotation in highly concentrated electrolyte solutions not only ionic strength but also chemical composition, flotation pH and mineral properties play an important role. As a result an improvement or depression may be observed. A strong improvement in the floatability of hydrophobic bituminous coals and other inherently hydrophobic minerals is characteristic for the "salt flotation process", which is carried out in concentrated electrolyte solutions at natural pH and without addition of any flotation reagents. However, pH is a key factor when saline and hipersaline waters with hydrolyzing metallic ions are used as process water. In the case of flotation of Cu-Mo sulfide ores in seawater, molybdenite is strongly depressed by the Mg2+ hydrolysis products when pH is raised to depress pyrite. Process water with a high content of Mg2+ and Ca2+ ions, and this also includes seawater, have deleterious effect on the anionic flotation of industrial minerals with fatty acids. The flotation of potash ores is carried out in NaCl-KCl saturated brine (6-7 mole/L of NaCl and KCl) with the use of long-chain amines. Such a high electrolyte concentration changes dramatically the amine Krafft point making the collector insoluble in brine; its mode of action entirely differs from that in conventional flotation processes.

Jan 1, 2014

By Diana Drinkwater, Tim Napier-Munn

"This paper argues that, although specialist mineral engineering expertise is essential for the efficient design and operation of mineral processing plants, the environment in which these skills are supplied to the industry has changed forever, and not for the better. Most of the mineral engineering programmes in western universities have died or are dying. The long-service mine site mentors have gone, operations are run on a staffing shoestring so that there is no longer the time (or inclination) for considered decision-making, and the FIFO model has discouraged continuity of optimisation projects and communication between professionals. At the same time the technical challenges of designing and operating effective process plants are increasing. These trends are not going to be reversed any time soon, if ever. The ability to run efficient mineral processing operations has been materially compromised as a consequence. We propose that well-designed professional development can help to recover this situation, and it can be done easily and cheaply. The workplace is the best environment for such skills development. Professional development training should be integrated with normal duties throughout the early years of a graduate’s service (and probably beyond), and the cost should be regarded as non-discretionary expenditure for the business. If such programmes are properly resourced and managed and extended over longer time periods, there will be a measureable rise in the level of technical understanding and competence within companies and a resulting beneficial impact on resource utilisation and thus shareholder value. The paper outlines some of the approaches that we believe will work, and the benefits that we expect will accrue."

Jan 1, 2014

By D. B. Dreisinger, M. R. Tavakoli

Vanadium has been produced from a variety of sources. This metal is known to make aqueous solutions of complex speciation as a function of vanadium concentration and pH. Considering the method of leaching, the impurities in the PLS and the planned vanadium product, different extractants and flowsheets can be applied for solution purification. In this paper, purification of vanadium leaching solution using organophosphorus, solvating and amine extractants will be reviewed. This review will be focused on vanadium separation from iron, molybdenum and uranium which are often present in vanadium resources including primary ores, fly ashes and spent catalysts.

Jan 1, 2014

By Zach G. Agioutantis

The Illinois Basin has an extensive history with the use of mechanized longwall mining dating back to the early 1970?s. In recent times, technological advances have resulted in increased panel widths from 800 feet to over 1400 feet and daily panel advance rates have also increased significant l. The prediction and control of subsidence and surface deformation due to underground mining are important considerations in the permitting, planning, and monitoring of these coal mining operations. The prediction of mining-induced ground movements using the influence function method is a mature technology, well utilized in the Illinois basin, and widely used by researchers and planning engineers around the world. This paper utilizes subsidence data, recently measured in longwall operations in Illinois, to develop an updated ground movement prediction capability implemented by the Surface Deformation Prediction System (SDPS) software package.

Jan 1, 2014

By X. Q. Cui

The surficial collapse pits of the mining areas are continuously spreading in Beiminghe iron mine of Hebei Province as a result of the exploitation, which has done a lot of damage to the circumjacent ecological environment of the mine. It is a new path to handle the mine tailings at the present time that the thickened tailings are used to backfill the collapse pits, in which way the problems of the surficial collapse and the nowhere discharge of the tailings are both solved, and the rational utilization of the mine tailings and the clean production of the mine enterprise are realized. The?200 mesh content of the tailings of Beiminghe iron mine is 76.87%, and?325 mesh content is 63.50%. Semi-industrial dehydration experiments to the tailings have been done using the hydro-cyclone classified thickening process. The results show that when FX125 hydrocyclone is adopted, the concentration of underflow can achieve 73.31%, and the yield ratio is 61.78%; when FX150 hydrocyclone is adopted, the concentration of underflow is 70.57%, and the yield ratio is 54.31%, which indicate that the minor diameter hydrocyclone is propitious to improve the yield ratio of the underflow. The semi-industrial dehydration system of hydrocyclone classified thickening process is com-posed of FX125 hydrocyclone, D3600 high-efficient thickener and D2000 thickening bucket. The capacity to tailings disposal can achieve 3.07t/h and the tailings can be thickened from 28.86% to 62.45%. Compared with the traditional thickening-filtrating process and the total tailings directly filtrating process, the hydrocyclone classified thickening process has the merits of simple flow and high thickening efficiency, so it is easy to be realized in the mine.

Jan 1, 2014

By I. Nolet

Matte tapping is one of the most critical operations of a matte smelter. Every smelter has developed particular matte tapping practices and tap-hole repair strategies that are often based on the experience of the smelter personnel. As a result, very little information has been published on these critical topics. This paper aims at providing the information gathered from a survey conducted in the PGM and Ni industries on matte tapping practices and tap-hole maintenance strategies for different PGM-Ni matte smelting operations.

Jan 1, 2014

By Honggang Zhong, Wei Du, Qijie Zhai, Junjie Sun, Jingzheng Ye

"Effects of pouring temperature and cooling water flux on solidification structure of ferritic stainless steel are investigated with a thermal simulation setup. The results show that with pouring temperatures 1518° C, 1528° C, 1538° C and 1548° C, both Lmean (the mean length between columnar to equiaxed transition(CET) position and chill surface of the samples) and the mean dimension of equiaxed grains increase. On the other hand, with cooling water flux 400, 800, 1200 and 1600mL/min, Lmean gradually increases, and the mean dimension of equiaxed grains decreases. In addition, low pouring temperature and cooling water flux enlarge the ratio of fine equiaxed grains.IntroductionFerritic stainless steel plays an important role in industry products nowadays. Compared with austenitic stainless steel which contains both chromium and nickel, ferritic stainless steel can obtain good corrosion resistance despite the absence of nickel [ 1]. F erritic stainless steel has been widely applied in automotive exhaust systems [2], electrical equipment, construction and chemical industries and also has broad development prospects. At present, continuous casting technique has developed into an important technology applied in iron and steel making. The solidification structure of continuous casting slab has significant influence on the final properties of stainless steel. The developed columnar grains of ferritic stainless steel would result in negative effects on mechanical property [3]. However, fine and homogeneou& equiaxed grains can improve the comprehensive properties of ferritic stainless steel [4] Therefore, it makes great sense to promote the columnar to equiaxed grain transition (CET). Recently Baosteel has developed a new type of Cr-saved ferritic stainless steel, but the effect of continuous casting conditions on its solidification structure is unknown. It is important to investigate the effects of solidification conditions on solidification structure of this new ferritic stainless steel, which can give guidance for optimizing the production process."

Jan 1, 2014

By M. Bryson, S. Broom-Fendley, A. E. Brady, W. Dawes, G. Beer, N. Sehlotho, S. Al-Ali, F. Wall

The Songwe Hill Rare Earth Element (REE) Project in Malawi is a near surface carbonatite-hosted deposit with synchysite and apatite as the key REE bearing minerals. A strong focus has been placed on understanding the REE mineralogy of the Songwe Hill carbonatite as REE mineralogical characterization is a crucial component at all steps, ranging from exploration to production, in the development of REE deposits. Extensive mineralogical work has been completed at Camborne School of Mines (CSM), Natural History Museum (NHM) London, British Geological Survey (BGS), Nottingham, Aberystwyth University, Wales, Mintek, South Africa, and SGS Inc. Canada (SGS). The following analytical techniques were used: scanning electron microscopy (SEM), electron microprobe analysis (EMPA), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and QEMSCAN®. The detailed studies have demonstrated that while synchysite is light-REE enriched as expected, apatite, abundant in all stages of carbonatite emplacement at Songwe, is anomalously enriched in mid- to heavy-REE relative to apatite in other carbonatite deposits. The distribution of REE within synchysite and apatite at Songwe has had important implications for the direction of the metallurgical work with respect to the behaviour of light and heavy REE through the flotation and hydrometallurgical stages of the flow sheet.

Jan 1, 2014

By N. A. Jabit

The dissolution behaviour of ilmenite in acid solutions has been studied by many researchers to improve the leaching efficiency. Most studies which utilized natural ilmenite from different origins resulted in different reactivity due to the alteration caused by the weathering process. Previous researchers have suggested that the greater reactivity shown by some ilmenite samples towards sulphuric acid may be a result of the mineral being relatively unaltered. In the present study a rotating synthetic ilmenite disc of 2.2 cm diameter was subjected to leaching studies in hydrochloric acid. The dissolution rates of iron and titanium from synthetic ilmenite were determined in hydrochloric acid solutions (4 M to 9 M) over a temperature range of 50 to 80°C. Results show that the rate of dissolution of both iron and titanium increased with the increase in acid concentration. However, the rates decreased with time and obeyed a parabolic rate law indicating the blockage of the surface by an insoluble product. The rates of dissolution of both iron and titanium were higher in the presence of SnCl2 and remained unaffected with time indicating the reductive role of SnCl2 which inhibits the formation of surface blocking solids. Application to natural ilmenite is also discussed.

Jan 1, 2014

By Z. G. Guan

The tungsten ore in Xingluokeng belongs to a symbiotic deposit containing granite and fine vein-type wolframite and scheelite. The tungsten (WO3wolframite) accounts for only 0.233% of the raw ore, 49.60% of the , 49.60% of the scheelite and 0.8% of the tungstite. The dissemination size of the tungsten ore is extremely uneven, with 0.02~1.28 mm for scheelite and 0.01~1.28 mm for wolframite. The dissemination size of scheelite is coarser than that of wolframite. The size of 83% of scheelite and 60% of wolframite is greater than 0.04 mm. The composition of minerals in the ore is quite complex. The major metallic minerals include wolframite, scheelite and pyrite, which are followed by molybdenite, chalcopyrite, arsenopyrite, limonite, magnetite, hematite and siderite. The major gangue minerals include quartz, feldspar, muscovite, biotite and sericite, which are followed by chlorite, fluorite, apatite, dolomite, etc. According to the dissemination features and liberation degree of the tungsten minerals, the technology flowsheet of gravity concentration for coarse particles and flotation for fine particles to re-cover the low-grade and fine vein-type tungsten minerals is adopted, and -0.7 mm is selected as the processing size. The closed-circuit grinding procedure, with the combination of the rod mill and high-frequency vibration screen, is adopted. The grinding product is classified into three products of -0.7 +0.2 mm, -0.2 +0.04 mm and -0.04 mm. The gravity separation is adopted for the former two to recover tungsten minerals and the flotation is adopted for the last one. Under the condition that the raw ore contains 0.23% WO3, some technology indexes of beneficiation have been achieved. The gravity tungsten concentrate contains 63.54% WO3 with the recovery 70.11%. The slime flotation tungsten concentrate contains 35.22% WO3 with the recovery 10.48%. The composite tungsten concentrate contains 57.53% WO3 with the recovery 80.59%. Thus, the tungsten minerals are re-covered effectively.

Jan 1, 2014

By Guanghui Li

Nickel pig iron (NPI), used as a substitute for electrolytic nickel, is able to reduce the production cost of stainless steel greatly. Aiming for preparing NPI from nickeliferous laterite ore, a pilot-plant scale test of coal-based rotary kiln direct reduction of laterite ore was performed and reported in this study. In this process, the ground laterite sample (18.85% TFe and 1.52% Ni) mixed with additives, pulverized coal and binder was briquetted into briquettes with the size of 40mm×40mm×31mm, laterite ore briquettes and reducing coal were charged into a rotary kiln with the diameter of 1.6 m and the length of 16 m, for a retention period of 6~7 hours, in which reduction section temperature was ranging from 950~1050 oC. The reduced briquettes were water quenched, ball mill ground and beneficated via low intensity magnetic separation. A magnetic concentrate, Ferronickel powder, with 86.9% TFe and 8.0% Ni was obtained, and the corresponding magnetic recovery of iron and nickel are 75% and 96.3%, respectively.

Jan 1, 2014

By Z. C. Zhen

Basing on character of fine ores, and employing all the advantage of dissolved-air flotation, the study within the dissertation put forth the methods of superfine metal mineral flotation with dissolved-air flotation equipment, and constructed a full set of laboratory flotation system. Experiments both in water and in slurry were respectively carried out by means of this flotation equipment. Further study was also fulfilled on mechanism of air-dissolved released devices, and the key components of system including ejector, releaser and saturator were designed. Optimizing devices parameters were chosen by taking ideal performance of the devices into consideration, according to orthogonal experiments and tests on bubbles factors, those performance factors were called air release rate, air release efficiency. The results with some minerals are better than JJF flotation machine with 30 litres bulk. The Dissolved-air Flotation(DAF) machine shows great potentiality in treating super-fine metal mineral concentration. The research indicates the Dissolved-air Flotation(DAF) system has superiority over mechanical flotation machine in fine flotation. Air-dissolved released bubbles appear on the surface of hydrophobic minerals in priority, solving collision probability less in the tradition fine mineral separation, such that the metallurgy technology of fine metallic minerals are improved. The exploratory research is a foundation for industrial pilot, commercial test and equipment maturity in the future.

Jan 1, 2014

By N. P. Mahumapelo

This paper is based on a study to determine the potential beneficiation opportunities for marble from Griekwastad in the Northern Cape Province. The marble was characterized mineralogically by X-ray diffraction. Major and trace elements were determined using inductively coupled plasma-optical emission spectroscopy. The sample was crushed, and the crushed material beneficiated by tumbling and polishing. The resulting beads were incorporated into a variety of jewellery and other decorative items. It is concluded that the beneficiation of Griekwastad marble presents a good opportunity for value addition and job creation, provided that an effective marketing strategy for the products can be developed..

Jan 1, 2014

By Yang Jian-guang, Deng Zi-xiang, Zhang Xu-liang, Li Jun-yuan

"Hyperaccumulator biomass harvested after heavy-metal phytoremediation must be considered as hazardous waste that should be contained or treated appropriately before disposal or reuse. As a potential method to detoxify the biomass and to convert this material to a suitable bio-energy resource, the hydrothermal upgrading process was applied to remove heavy metals and upgrading crude bio-oil from Pteris vittata stems and leaves harvest. Parameters such as material granularity, temperature, Liquid/Solid (L/S, ml/g), pressure, duration and catalysts were examined for their effect on the removal efficiency of heavy metals and upgrading efficiency of crude bio-oil. Maximum heavy metal removal efficiency of>99% and crude bio-oil upgrading efficiency of 83% were attained with an 200 mesh (75 µm) granularity, LIS 40:1and23 MPa at 380°C in the presence ofO.l mol L-1 K2C03 for 30 min. GC-MS analysis results show that the resulting bio-oil mainly consists of benzene 11 %, ketone 42%, alcohols 14%, alkene 15% and ester 11 %, etc., and the relative molecular weight distribution lies in 94-282, carbon number distribution lies in 6-18, calorific value is 32MJkg-1.IntroductionPhytoremediation of soil or water with hyperaccumulator has been extensively explored in recent years [1-4]. Living plants can clean up soils or waterways. This approach exploits the ability of various plant species to thrive in high metal environments where large amounts of toxic elements are accumulated, such as heavy metals, and is particularly appropriate when slow remediation of relatively low metal concentrations is acceptable. Advantages compared with existing remediation methods include the minimal site destruction and destabilization, low environmental impact, and favourable aesthetics; advantages compared with biosorption include continuous in situ regeneration of the biomass, and the ability of living plant cells to supplement passive sorption of metals with metabolic mechanisms of metal uptake and detoxification [5-8]."

Jan 1, 2014

By A. Dienenthal

"The casthouse floor has always been one of the most dangerous working places on a blast furnace or a ferro-alloy/nonferrous furnace. Apart from working in an atmosphere including toxic gases, fumes, and dust, the workers have to perform hard and heavy manual work close to runners and ladles filled with hot liquid metal and slag.Before the invention and installation of tapping equipment the tap-holes were opened and closed manually. Opening was done by means of steel bars and sledgehammers, whereas the tap-hole was closed by repeatedly ramming small amounts of clay or refractory material into the tap-hole, again with the help of long, heavy bars. In addition, on blast furnaces the blast had to be stopped, since it was impossible to close the tap-hole properly against the blast furnace pressure. This stoppage of the blast resulted in regular losses of production. Around 1900 a major change in technology occurred. Samuel W. Vaughen, superintendent of the blast furnace department of the Cambria Iron company at Johnstown, Pennsylvania (USA), invented the first clay gun in 1895 (Wiley, 1896) (Figure 1)."

Jan 1, 2014

By Marko Hilden

"A stochastic model of mineral texture is discussed and used to demonstrate that grain association within the intact texture has a significant effect on the liberation characteristics of breakage products. The majority of previous models have simulated texture and liberation of binary systems. This new model is able to simulate complex multi-component (multi-mineral) aggregate textures and their breakage products. Grain size distributions can be defined for each of several minerals. Mineral-mineral associations can be controlled by inserting mineral grains within grains of another mineral. Repeated Monte Carlo sampling of the aggregate is used and the liberation properties of the fragments are calculated. These are analysed to generate data in a similar form as reported by mineral liberation analysis systems, including density distributions, liberation distributions, and particle class distributions. Simulations results are presented where the model has been fitted to complex sulphide ores with four minerals. Comparison of the simulated particles and experimental data show that the model is able to reproduce similar particle class distributions as measured by QEMSCAN. The texture of real complex ores can be simulated and fitted to conventional mineral liberation analysis data. The model should provide a useful and practical means of modelling the effects of mineral texture on separation processes and in geometallurgical models."

Jan 1, 2014