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By W. Rubarth

The kaolin losses in hydrocyclone classification are determined by the fines, which are discharged together with the water to the underflow. This paper presents an improved technique of water injection to the conical part of the cyclone applied especially for small cyclones in kaolin preparation. In small hydrocyclones water, injection is a sensitive process. Therefore, the process was stabilized by controlled water injection dependent on the measurement of the underflow shape. Three applications of this innovation are presented. In the first case, the water injection is applied for the separation stage in dilute suspension where the final product is produced in the overflow of a 50mm hydrocyclone. The underflow contains sand and residual kaolin. For a higher kaolin recovery, the underflow is usually treated downstream in washing cyclones. The wash water injection results in a 45 ? 50% - reduction of the kaolin fraction <25µm in the underflow. Thus, water injection to the classifying cyclone leads to a separation comparable with a downstream washing stage. An additional hydrocyclone stage can be deleted. The second application refers to a classification in dense suspension. Here, the underflow of the last hydrocyclone stage was directed to a washing in a 50mm hydrocyclone. The additional injection of 3L/min water in to the conical part of the cyclone reduced the kaolin losses by half.The third application was executed in the washing stage equipped with 75mm hydrocyclones where the underflow is directed to flotation. Using the water injection the kaolin recovery in this stage was increased by approximately 20%. Keywords: hydrocyclone, classification, kaolin beneficiation, water injection, underflow washing

Sep 1, 2012

By Shugang Hu

According to XRD, DTA and SEM detections, the hydration products of blast furnace slag (BFS) based cementing material SL, SLG. were studied in different age periods. The XRD analysis of cementing material SL hydration products showed that the composition of hydration products were mainly amorphous substances, few crystalline substances. Characteristic peak of ettringite hadn?t been found in the spectral line of DTA, and it hadn?t been found in the figures of SEM, either, which was accordant with the conclusion that the cementing performance of SL mainly coming from gel of hydrated calcium silicate (CSH) and hydrated calcium aluminate. However, the main hydration products of SLG are Aft, CSH, and AFm, which are similar to Portland cement. All results suggest that BFS is a suitable base material for cementation. Keywords: blast furnace slag, backfilling cementing material, hydration products, cementing performance

Sep 1, 2012

The simulation study on the process of iron ore beneficiation plant of Essar Steel, Kirandul was carried out. The iron ore fines and slimes generated nearby Bailadila mines of NMDC are used as raw materials for this beneficiation plant. The capacity of the plant is 1400 TPH operating in parallel in two streams. The capacity of the plant was utilized about 60% of throughput capacity. To improve the plant capacity as well as quality performance, the simulation study was conducted to detect the bottleneck of the process. The process samples were collected from input and output of each processing unit operation to generate the data base for simulation study at the feed rate of 400 and 500 TPH of iron ore fines in a single stream. The characteristics data i.e., breakage and selection functions were generated using MILLSOFT package for simulation of ball mills. Then MODSIM package was used to evaluate the performance of each unit operation to identify the bottleneck. It was established by a simulation study that the intermediate thickener draws high current when the feed rate is more than 400 TPH due to high torque drawn by rotating rake because of presence of coarse particles in the input stream to thickener. The problem was sorted out by classification of input stream of thickener to remove the coarse particles. Then the process was simulated at its rated capacity, and experimental validation studies at the plant were also conducted at the feed capacity of 600 and 700 TPH by modification of process flowsheet. The experimental data was almost matching with simulated data. Finally, the processing plant is running with full rated capacity without any bottleneck. Keywords: simulation of ball mill, breakage function, selection function, iron ore

Sep 1, 2012

By M. Tang

The phosphate ore sample was taken from the iron tailings after recovering most of magnetite by magnetic separation in Longlin, Yunnan Province of China. Batch flotation tests had been conducted to upgrade the phosphate concentrate by conventional fatty acids reagents under 70% -75 µm of the particle size; however, the unsatisfied results (P2O5 grade of 27.84% and recovery of 49.25%) were obtained. Also there are a large amount of slimes trapped in the concentrate and high-dosages consumption of reagents, for example, more than15 kg/t soda ash and 2 kg/t sodium silicate at only one-staged roughing. Based on the analysis of X-ray diffraction (XRD) for the sample, most of gangues are clay, quartz, and chlorite, which may easy to over-grind and deteriorate the flotation process either on reagents consumption or slurry fluidity or viscosity. A hydro-cyclone had been introduced to pre-concentrate the phosphate ore by scrubbing the slime before flotation, which can result obviously in reducing the dosages of soda ash from 15 Kg/t to 4 Kg/t, and raising the grade of P2O5 in the concentrate from 27.84% to 36.13% at the expense of about 4% recovery of P2O5. They also substantially reduced the time of sedimentation of concentrate after flotation from ~10 to ~1 min. In this paper, the effects on the recovery of P2O5 by the different dosages of flotation reagents with or without de-sliming were studied, with the objective of determining the different effects on the functions of flotation reagents by slime during flotation. Keywords: de-sliming, phosphate, soda ash, flotation

Sep 1, 2012

By D. W. Feng

Thiosulfate as an alternative lixiviant for gold has received much attention in recent years due to the growing environmental concerns over the use of cyanide. Cu(II) is used to catalyze the oxidation of gold and ammonia is to stabilize Cu(II) in alkaline solution. However, the presence of Cu(II) enhances the oxidative degradation of thiosulfate. The high consumption of reagents has made thiosulfate leaching uneconomical to date, in comparison with cyanide leaching. Therefore, further investigations are required to leaching under low reagent concentrations over extended periods where reagent consumption is low and gold leaching rate is low as well. It is thus necessary to find additives to enhance gold dissolution in the thiosulfate leaching system. Electrochemical studies using rotating gold disc showed that the oxidation of gold in ammoniacal thiosulfate solution increased significantly in the presence of a small amount of thiourea and the beneficial effect increased with an increase in the thiourea concentration up to 7.2 mM. Thiourea improved gold extraction in the thiosulfate leaching of gold from a sulfide ore under low reagent concentrations. Excessive addition of thiourea inhibited the leaching of the gold ore. The decomposition of thiosulfate was reduced with the presence of thiourea. X-ray Photoelectron Spectroscopy (XPS) results indicated that thiou-rea likely decomposed to sulfide and formed gold sulfide species at the gold surface.

Jan 1, 2014

By Yuexin Han, Jie Liu, Shuai Yuan, Yanjun Li

"In order to improve recovery efficiency of iron minerals from iron ore tailings and to reduce its connected environmental pollution, this article investigated the reducing roasting of iron ore tailing in a laboratory fluidized magnetization roasting reactor to optimize the roasting method and conditions. The examined parameters included roasting temperature, roasting time and reducing atmosphere. The parameters evaluating magnetizing roast efficiency and theoretical value were determined. X-ray diffraction (XRD) analysis was used to investigate the conversion of iron phase after roasting. The results show that the best magnetizing roast conditions are roasting temperature of 540?, holding time of 15min, and CO concentration of 20%. The magnetization conversion ratio of roasting products is over 80%, under the best magnetic separation condition, the concentrate grade of iron is 65.61 % and the recovery of iron is 83.77 %. The XRD analysis shows that Fe exists in hematite and siderite before roasting and exists in magnetite after roasting. The technique not only recovers the iron minerals from tailings with good economic benefit, but also reduces the environmental pollution of tailings accumulation.INTRODUCTION Iron ore tailings are the solid wastes generated during the beneficiation process of iron ore concentration and are one of the main pollution concerns in the mining industry (Das et al., 1996). Continuous development of the iron and steel industry has led to the increasing amount of iron ore tailings; there are over 300 million tons of iron ore tailings discharged per year (Rao et al., 2016). The huge amount of stockpiled iron ore tailings brings a series of environmental and social problems. Comprehensive utilization of iron ore tailings can not only reduce environmental load but also conserve resources, promoting sustainable development of the society. In recent years, iron ore tailings as secondary resources have received considerable attention in many countries in the word and numbers of studies on utilization of iron ore tailings were carried out, such as recycling the valuable minerals (Datta et al., 1996; Jia et al., 2013; Panda et al., 2018), used in construction material compositions as alternative source of raw materials (Das et al., 2012; Zhou et al., 2012; Luo et al., 2016) and other utilization. The iron minerals were recovery by magnetization roasting (Rao et al., 2016; Yang et al., 2013; Yang et al., 2011) and flotation (Kumar and Mandre, 2016). By comparison the reduction roasting has more advantages, but it was found that the conventional roasting equipment was inefficient, high energy consumption and un-economically applied on an industrial-scale."

Jan 1, 2018

By Janne Kytökari

Controlling a wide range of minerals processes with single control system is an ordinary way to operate in mines all over the world these days. However the potential of these systems is not yet fully recognized nor utilized. The key issue is to manage the information in a way that enables automating the day-to-day tasks, quality control and safety functions. At the same time it provides means for optimization and constant improvement of processes creating a working environment where the system helps employees to do their key tasks instead of searching, modifying, and transmitting the huge number of information arising every day. The distribution of control system nodes enables the other processes to run heedless of a problem occurring in one of the sub-processes. Also the control room can be in remote location such as in large city removing the need to travel substantially long distances to plant sites every day. When all essential information is brought to the same place there is less risk for a mishap to happen due to information breaks that are often the cause of them. One of the biggest single reasons that result in production losses are break downs of machinery usually caused by normal wear, misuse, incorrect utilization rate etc. For this reason it is important to measure the condition of machines using vibration measurement and diagnostics. By moving from failure or time-based maintenance towards predictive or performance maintenance generates eventually a steady and predictable process but also results in significant long term savings. The mineral process at Talvivaara mine is based on bioheapleaching, whereby metals are leached from ore as a result of bacterial action. Bioleaching is a fairly new technology used in metals recovery. Therefore it is important for the mine to collect and analyze data from different stages of the minerals process. Talvivaara mine?s Metso DNA system has integrated machine condition monitoring and information management. These are not only necessary but also crucial in environmental conditions where the outside temperature can drop below -35°C, where ice and snow dominate the landscape and impact the equipment for four months a year and where distances between equipment can be up to 7.5 kilometers. Keywords: DCS, analyzer, machine condition monitoring, automation, remote communications, optimization, mining, metso DNA, Talvivaara

Sep 1, 2012

By V. K. Gupta

Several approaches to the estimation of the size discrete breakage rate and distribution parameters (kj and bi,j ) of the batch grinding kinetic model are available in the literature. Analysis of a large amount of data available in the literature and our own data on several pure minerals and complex ores has shown that it is not always possible to obtain correct estimates of the two sets of parameters using known approaches as several widely different combinations of k and b parameters can sometimes simulate the batch grinding data reasonably accurately. It has been found that there are two main reasons: (i) all size classes are not well represented in the data and (ii) functional forms used for estimation of the two sets of parameters are sometimes chosen somewhat arbitrarily (especially in the case of complex ores), though they are actually uniquely related through size continuous breakage rate and distribution functions. A suitable experimental methodology has been described and demonstrated using some synthetic data and actual experimental data. A mill function approach, which does not require making any assumptions about the functional forms for k and b parameters, is also described and demonstrated. This approach is promising, but requires further development.

Sep 1, 2012

By Sun Chuanyao, Cao Fei, Sun Desi, Zhou Dezhi

"The research applies the density functional theory and molecule design technology to design and synthesize the novel flotation collectors for copper-sulphur separation. Density functional theory (DFT) was applied to investigate the electronic properties of O-isopropyl-N-benzyl thionocarbamate (IP-BIAN) and O-isopropyl-N-ethyl thionocarbamate (Z-200). The calculation results show that both the energy of highest occupied molecular orbital (EHOMO) and the lowest unoccupied molecular orbital (ELUMO) of IP-BIAN are smaller than that of Z-200, electronegativity of IP-BIAN is higher than that of Z-200. According to the Klopman’s generalized perturbation theory, the collecting power of the two compounds is predicted to be Z-200 > IP-BIAN, the selectivity of IP-BIAN is better than that of Z-200. Then the thionocarbamate molecular is synthesized, and the compounds are characterized by nuclear magnetic resonance (NMR). It turns out that the test result identifies the prediction after the flotation verified test of pure mineral and actual mineral. The results demonstrate that the EHOMO and ELUMO are smaller in the thionocarbamate after a nitrogen atom is bound to benzyl, the thionocarbamate has strong selectivity and low collecting power. The lower the LUMO energy of thionocarbamate is, the stronger the back donation covalent p-bond between collectors and chalcopyrite is, thus improving flotation power for chalcopyrite and selectivity against pyrite. The result proves the feasibility of design and synthesis of the novel thionocarbamate through the frontier orbital properties of the collectors.1. INTRODUCTION Thiocarbamate is a kind of nonionic polar collector and is now widely used as flotation collector for copper-sulphur separation. The flotation power of thiocarbamate to chalcopyrite is stronger than pyrite, so it has high selectivity against pyrite. The frontier orbital theory and density functional theory (DFT) has been widely applied to study the structure-activity relationship of flotation collectors [1-6]. The flotation test results can be interpreted by using the reaction energy criteria and quantum-chemical parameters, such as the energy of the highest occupied molecular orbital (EHOMO) and the energy of the lowest unoccupied molecular orbital (ELUMO) of collector [7-11]. In turn, there are rarely reports about screening the novel flotation collector, by the frontier orbital properties such as HOMO and LUMO of flotation collectors. In this thesis, we apply the density functional theory and molecule design technology to design and synthesize the novel flotation collectors for copper-sulphur separation. Based on the previous findings of the structure-activity relationship of xanthogen formats [12], it has stronger collecting ability to chalcopyrite while the xanthogen formats after a nitrogen atom is bound to benzyl. Thus, in this study, a novel thionocarbamate molecule O-isopropyl-N-benzyl thionocarbamate (IP-BIAN) will be constructed, when the group structure connected with N atom in the known collector O-isopropyl-N-ethyl thionocarbamate (Z-200) is replaced with ethyl by propyl. The collectors (IP-BIAN and Z-200) have been calculated by DFT methods in quantum chemistry. By analyzing the reaction energy criteria and the frontier orbital properties (HOMO and LUMO), this research predicts flotation performance of novel collectors (IP-BIAN), then the synthetic experiments and flotation verified tests are conducted. The research provides a new theory reference for screening out the high-effective flotation collectors of copper-sulphur separation. This technology adoption will contribute to the sustainable development of mineral resources as it shortens the research cycle of new collector molecules and reduces the investment."

Jan 1, 2018

By A. S. Chekmarev, T. Z. Lygina, K. G. Egorova, A. V. Skvorcov

"We have conducted analytical and technological evaluation of sepiolite containing clay. The possible areas of application of the sepiolite have been investigated and complex methods of enrichment of natural sepiolite have been identified. It was determined that for preserving the structure of minerals after processing the most effective method of the natural agglomerates disintegration was the soft abrasion of the clay fraction up to 0,5 mm. Disintegration of sepiolite clay along with using high energy-stressed effects on the matrix can deteriorate the rheological properties of clay suspensions and reduce the yield of drilling mud and sorption properties. To improve the quality of clay powders we used combined gravity-modifying method of wet enrichment. After the wet enrichment the yield of drilling mud increased up to 12.7 m3/t, with the addition of MgO up to 20,3 m3/t. It was noted that drilling muds contenting more than 50% of sepiolite are stable in mineralized (salt) waters. Based on the studied activated sepiolite rocks we obtained the effective heat-insulating materials with relatively low thermal conductivity – 0,165 W/m·K, average strength – 7,29 MPa and water absorption-49,0%.INTRODUCTION The modern development of the Russian economy requires the implementation of scientific and technical tasks. The solutions of it involves a radical reduction in energy, heat losses and material consumption of products, rational and efficient using of all types of resources, as well as the using of new types of mineral raw materials and materials based on it. An example of a new type of mineral raw materials for Russia is sepiolite containing rocks, due to unconventional conditions for their soils accumulation in the climate of the Far North. Sepiolite is a unique type of nonmetallic mineral. It is formed in soils, marine and saline basins, occurs in carbonate and carbonate-clay rocks in the form of lenses and lens – shaped layers, rarely nodules, loose powdery masses, shell-like concretions. Sepiolite may have a soft porous macroscopic appearance or less often the structure of the fibrous mass. Color of sepiolite is from white to cream with gray, green, pink and even crimson shade depending on the degree of pollution. Sepiolite can be in two forms - a-sepiolite (parasepiolite), which occurs in the form of large packets of crystalline fibers and ß-sepiolite, which occurs in the form of amorphous aggregates or small flat rounded particles. The sepiolite fibers have a length of from 0.2 to 2 Å, width from 100 to 300 Å, the thickness from 50 to 100 Å (Geological dictionary, 1973)."

Jan 1, 2018

By C. Y. Sun

In this paper, the development of research and practice on the separation process of fine complex Cu-S ore at a Copper Mine in south of China, was discussed. Since early 1980s, various processes were used, such as the process of bulk flotation-separation, the process of selection flotation and the process of iso-flotation. Especially when the process of selective flotation was put into operation, further development was achieved in beneficiation results, but the difficulty in separation of chalcopyrite from pyrite has not been solved yet, so causing a poor quality of Cu concentrate. The author has successfully developed a new separation process characterized by the use of collector thionocarbamate and fast flotation. The selectivity of fine chalcopyrite and pyrite was greatly improved. This process supplied a new route for the treatment of fine complex Copper sulphide ores.

Jan 1, 2014

By D. Saramak

The proposal of the nip zone angle determination in HPGR crushing process is presented in the paper. Knowledge of the nip zone angle value, in turn, makes it possible to determine the real maximum pressing force in the high-pressure comminution. Two methods of determination of this maximum pressure were proposed and verified. The first method is based on the roll?s geometry, and the change of the HPGR chamber?s volume together with the roll rotation, while the second one considers the outlet gap width impact. Results of the nip zone angle calculations according to both methods are similar and show convergence with the real operating conditions. The verification was carried out in a piston-die press, and experimental results show that methodology of the nip zone angle determination presented in the paper has its practical confirmation. A proper determination of the nip zone border makes it possible to calculate the comminution probability of given type of material and is a basis for the HPGR crushing process modeling and optimization. Keywords: HPGR, comminution, nip zone, ore processing

Sep 1, 2012

By J. Jirestig

Poor grade iron ore, suffering from interlocked particles, is challenging for any process technology. Extensive grinding is required to attain liberation and to yield concentrates of desired grade. Fine particles are commonly very difficult to retrieve, resulting in value losses to tailings. In this paper, results from HGMS tests on fine to ultra fine hematite are reported. Special emphasis is put on slurry flow velocity. If hydrodynamic drag force, i.e. flow velocity is not controlled and kept constant during the feed and/or rinse phase, fine particles will not be captured and retained. Flow velocity control and constant flow during separation are achieved by discharge valves/slots and parallel magnetic flux and pulp flow configuration. In tests, increased slurry velocity from 178 to 268mm/s caused Fe-recovery to drop from 78 to 48%. Proving that flow velocity control is essential to optimise grade and recovery. HGMS tests at the Metso mineral laboratory on natural (weathered) hematite fines clearly show a large potential to recover valuables, currently lost to tailings. Even at particle size distributions as low as D80=35µm concentrate grades and recovery are very satisfying. Two samples, in-plant desliming rejects (D80=35µm and 50µm) where significantly upgraded and recovered, from 45,3% to 63,6% and 53,0% to 63,4% Fe, at 73,8% and 81,1% Fe-recovery respectively. Other types of in plant rejects, such as gravity separation or WHIMS tailings, also benefits from HGMS separation. Gravity separation reject, 55,8% Fe, at D80=500µm was tested, yielding a magnetic concentrate of 60,8% Fe at 50,7% Fe-recovery. The results indicated that the hematite was poorly liberated. HGMS separation was repeated after a regrind to D80 150µm, resulting in a magnetic concentrate of 62,8% Fe at 75,9% Fe-recovery. The tests prove that hematite, presently lost to tailings streams, can be recovered by HGMS and thereby significantly contribute to improved overall economy. Keywords: HGMS, magnetic separation, recovery of ultra-fine hematite, Indian hematite ores, hematite recovery from tailings

Sep 1, 2012

By L. X. Zeng

The low-grade nickel resource is very abundant in the western China. To make the best of the low grade nickel ore, we studied the process mineralogy and beneficiation process of nickel ore in the Yangliuping of Sichuan province. The grade of nickel is 0.45% in the nickel ore and the nickel exists in the sulfide including pyrrhotite, nickel pyrite, chalcopyrite primarily. The nickel distributes in pentlandite and magnetite over 90% and the copper does in the chalcopyrite over 95%. The carri-er minerals of useful elements tend to concentrate in space for concentration. As is shown in grain-size analysis of three major minerals, there are some more fine-grained grains with the percent of from 10% to 15% (<40 µm) and from 3.5% to 5.5% (<20 µm). So there will be some smaller size disseminated sulfide minerals difficulty to liberate in the process of concentration. The liberation degree of sulfide is not high and there are much associativity in the sulfides. Therefore, we should reclaim the sulfide aggregation dominating as pentlandite when concentrating. In addition, the sulphide minerals is so brittle that we should take care of preventing from crashing when grinding. The gangue mineral is mostly metamorphic mineral including serpentine, chlorite and amphibole which is easy to be argillization and difficult to concentrate.

Jan 1, 2014

By S. Banisi, O. Farshid, M. R. Rozebehi, A. Bahar, A. Arghavani, M. Mahdavi

At the rougher flotation circuit of the Miduk copper concentration plant (Kerman, Iran) five column cells (CISA) with the diameter of 4m and height of 12m using static mixer type (MicrocelTM) spargers have been installed. Based on the initial design, columns should accept a feed rate of 625 t/h with 80% passing size of 90 µm and solids concentration of 28% and produce 88% of the plant concentrate (i.e., 22 t/h) containing 32% copper. Due to mechanical and processing problems this objective was never realized and theses columns were remained out of operation from the commissioning time (2005). A new attempt with the aim of returning these cells into operation started in 2013. The results of an extensive study indicated that spargers plugging due to the entrance of small amount (2 kg) of coarse particles (up to 2.5 cm) because of usual problems at the plant environment was the main reason of columns non functionality. With a change in the recycle pump inlet design to the column, which prevented the entrance of coarse particles to the spargers, the operation of the column significantly improved. It was found that in order to have a stable operation of the columns at the rougher stage the feed rate for each column should be reduced from 125 (design) to 70 t/h. The air superficial rate had to be also reduced from 1.9 (design) to 0.6 cm/s. A period of 10 days of continuous operation showed that the carrying capacity was 0.23 (g/min/cm2) which was significantly lower that of the design value (i.e., 0.58). The gas hold up was found to be lower than 10% beyond which columns started to move to the turbulent state indicated by "boiling" froth. The average life time of spargers was determined to be 20 days which considered to be very short. The average recovery and concentrate grade of these columns were found to be 68% and 32%, respectively. The high wear rates of spargers, unusually high level of maintenance and supervision needed and instability of the operation made the plant managers not to use column cells as the roughers.

Jan 1, 2014

By Paul Gottlieb

This paper reviews the status of automated applied mineralogy today and describes the history and fundamental theoretical and practical bases underpinning the development of automated systems. Details are given of the technical challenges that were faced in creating the new technology and in applying it to a range of applications. In recent years, automated mineralogy has become established as an essential enabling technology for the reliable acquisition of statistically sound comprehensive mineralogical and metallurgical data. This has had a revolutionary effect on the industrial use of such data in the study of geology, mining and mineral processing. Previously, using manual methods, it was not feasible to attempt this work because the large data sets required could not be assembled in a realistic timescale. There was a reliance on individual expert mineralogists and this was not scalable. The speed, reliability, detail and repeatability of the modern automated measurements has now made this type of analysis routine. Automated Applied Mineralogy has come of age! More than 100 systems have been installed around the World. Automated mineralogical analysers such as QEMSCAN® were originally developed as diagnostic metallurgical tools to improve mineral processing plants using samples drawn from plant surveys, bench and pilot-scale tests. They were used mainly for the assessment and auditing of size fractions of mill products, such as concentrates and tails. Subsequently, they began to be used for concentrator design and optimisation where ore characterisation was used to help understand the relationship between the feed ore and its subsequent behaviour in the plant. They are now widely used to measure exploration cores and drill chips from drilling programs to predict eventual metallurgical performance. Ore samples can be classified into metallurgical, as well as geological types, by combining mineralogical features in the ores with metallurgical properties related to grade control, separation, comminution, flotation and leaching behaviour. Three-dimensional block models of ore deposits are now being created based on processing response in addition to geological and mining properties. The development of automated systems began in Australia, the United Kingdom and Canada in the late 1970s and early 1980s. There were many technical challenges. Mathematical theories of randomness, sampling theory, image analysis and stereology were developed to ensure sample representivity so that meaningful information could be obtained. Sample preparation, presentation and measurement methods were developed to ensure that the random sampling was preserved during the measurements. Methods of automatic measurement and mineral identification evolved from the use of electron microscopes, fitted with backscattered electron brightness and energy dispersive X-ray detectors. Operational procedures were required to ensure that these instruments could accommodate a large number of samples and operate unattended for long periods of time. The new technology was progressively applied to a range of commodities and applications and new analysis methods, such as liberation measurement, were needed for metallurgical interpretation of mineralogical data.

Jan 1, 2014

By Chuanyao Sun, Zhenguo Song, Aijun Ren

"Lead-Zinc sulfide ore containing carbon is one of typical refractory resource. Because organic carbon has natural floatability, it has a great negative influence on flotation of lead-zinc sulfide ores. It is difficult to obtain qualified lead concentrate by flotation using conventional reagent system. In order to reduce the influence of organic carbon on lead and zinc flotation, two alternatives, i.e., removal carbon by pre-flotation or adding carbon depressant in lead and zinc flotation, can be adopted. If the flowsheet of removal carbon by pre-flotation is adopted, the lead and zinc recovery which are lost in the carbon tailings is often higher. If conventional carbon depressants are used in lead and zinc flotation, it has a certain depression effect on lead minerals. In the paper, the ore grading 1.49% Pb, 5.73% Zn, and organic carbon 3.14% has been carried out by flotation tests. In the bulk flotation of carbon and lead minerals, Pb concentrate is only about grading 21.00% Pb. In the pre-flotation of organic carbon, it’s hard to remove most of carbon, and the loss of Pb and Zinc recovery is too much in carbon tailings. New carbon depressant BK547 and three conventional carbon depressants including sodium lignosulphonate, Fe-Cr-lignosulfonate, and dextrin, are used in comparative tests of Pb flotation, and results show that BK547 have a good depression on organic carbon, and have almost no effect on Pb flotation. Using BK547 as carbon depressant, cycle test in flowsheet of two-stage Pb and Zn selective flotation and coarse concentrate regrinding have been carried out, and results show that concentrates grading 62.51% Pb and 41.33% Zn are obtained at recoveries of 70.24% Zn and 83.58% Zn.INTRODUCTION Lead and zinc mineral resources are still the main source of lead and zinc metal. For lead-zinc sulphide ore, lead concentrate and zinc concentrate are obtained by flotation. Minerals separation by flotation is a complex process and is dependent, along with other factors, on the relative distribution of hydrophobic (e.g. collector, polysulfide, elemental sulfide) and hydrophilic (e.g. metal hydroxide) species between different particles of the same mineral phase and between mineral phases (Piantadosi & Smart, 2002; Boulton, Fornasiero & Ralston, 2003). Organic carbon has natural floatability and is often associated with lead-zinc sulphide ores. If the content of organic carbon in the ore is more, the flotation index will become worse. The main problem is that the concentrates has too low grade to be qualified grade products for sale. At the same time, the consumption of reagents is more than ordinary ores without organic carbon. In order to solve the influence of organic carbon on the flotation of lead and zinc and other sulphide ores, a lot of research works have been carried out."

Jan 1, 2018

By Ofra Damm, v du Preez, D. van Vuuren, L. Simpson, H. Chikwanda

"South Africa is the world?s second largest producer of titanium bearing minerals, but apart from producing titanium mineral concentrate to form TiO2 slag, little further value is added in South Africa to mined minerals. Various studies were undertaken by both government and the private sector in an un-coordinated manner until 2007 when the South African Department of Science and Technology (DST) planned and adopted a national strategy to establish a local titanium metal industry through the research and development of key technologies that would provide a competitive advantage to such a local industry. The strategy entailed a two-pronged approach in the development of this capability, viz. simultaneous investments in the development of high-level human capital and technology in the fields of titanium metal powder production and downstream titanium metal powder processing technologies. To date significant progress has been made to establish research and/or pilot scale facilities in the following technical areas: TiCl4 production technology, titanium powder production technology, high energy milling of titanium powder, metal injection moulding facilities, rapid production of large components using laser additive manufacturing technology, investment casting of titanium, resource efficient machining of titanium and friction stir welding of titanium. Supporting technologies are also at an advanced stage through investments in titanium powder spheroidization and direct rolling of titanium powder. The intent with investment in some of these areas is not to develop new technology per se, but rather to establish local capability that will position South Africa to collaborate with other organisations in the world so that technologies can be acquired and transferred when needed in the future."

Jan 1, 2014

By R. K. Rath

The low-grade iron ore sample contains both lumps and fines. It is mostly hematitic iron ore and considerable amount of goethitic/limonitic material is present in it. The major impurities present were quartz and clay. It is observed that the iron bearing phases are poorly liberated above 300 µm and the liberation improves below 300 µm. More than 80% liberation is achieved below 106 µm. Based on the liberation data, the feed for the different beneficiation methods was prepared by stage crushed the ROM followed by grinding passing to 106µm and the ground material (-106µm) was deslimed. The underflow was subjected to various beneficiation techniques such as tabling, enhanced gravity separator (EGS), wet high intensity magnetic separation (WHIMS), and flotation and the results are discussed. All the methods studied could able to produce pellet grade concentrate with iron content of 64.5%, however, a marginal higher yield was observed for WHIMS (81%). Keywords: beneficiation, gravity, magnetic, enhanced gravity separation, flotation, low-grade iron ore, desliming

Sep 1, 2012

By Jerzy A. Mielczarski

The separation of albites from quartz by flotation applying the conventional HF-methods is no longer acceptable from an environmental and health point of view. Therefore, the search for a new reagent scheme without using HF depressor for separation of albite from quartz is under consideration. The flotation behaviour of ore mineral components depends on the produced hydrophobic or hydrophilic surface coverage (chemical functionalization). Currently we have excellent possibility of monitoring surface composition and structure at molecular and atomic levels at surfaces of natural minerals contacted with aqueous solutions of collectors, activators, depressants which is vitally important for the understanding of the surface chemistry that govern selective and efficient flotation. Detailed surface characterization of minerals before and after their exposition to different solution conditions was performed by the most modern spectroscopic techniques such as developed by us the infrared external reflection technique combined with spectral simulation and X-ray photoelectron spectroscopy (XPS). It is possible to monitor surface reactions which facilitate the separation process and those which bring disadvantage to selective flotation. At first we found that a small amount of ?mineral impurity? presented in natural ore could play important role in selective hydrophobization process. It was found that the pH of solution (parameter possible to control) and natural mineral impurities present in mineral samples (parameter related to ore origin) play a very important role in the separation process. Another important parameter is interaction between minerals, quartz and albite, present in aqueous solution. The limitation of flotation separation resulting from chemistry will be discussed. Moreover, the most promising scheme for separation of albites from quartz will be examined.

Jan 1, 2014