Search Documents

By P. T. Nguyen

The analysis of particle capture by an air bubble by two separate phenomena of collision and attachment has been difficult due to the uncertainty in determining when and where the two phenomena begin and terminate at the bubble surface, respectively. Therefore, a unified analysis was developed by solving the motion equation for the particle capture as one process. No distinction be-tween collision and attachment was made. Both the liquid film described by the micro-hydrodynamic resistance functions and the surface forces were included in the new model. The model predictions with the DLVO (Derjaguin-Landau-Verwey-Overbeek) surface forces did not agree with the experimental trajectories of latex and silica spheres. The model predictions with the inclusion of the non-DLVO attractive surface force agreed with the experimental data. The non-DLVO force reduced the repulsion between the non-attaching particle and the bubble, and significantly increased the attraction between the attaching particle and the bubble. The unified analysis is capable of predicting particle capture without the use of the induction time. The unified analysis also shows significant influence of the short-range hydrodynamic interactions on the collision which has been previously ignored.

Jan 1, 2014

By Ranjeet K. Singh

Kelsey Centrifugal Jig was found to be promising for the beneficiation of fine coal particles. The present study was aimed at in-depth understanding of the separation features of Kelsey Jig through detailed experimentation. Beneficiation of fine coal of size 150 x 300 µm was studied in a laboratory Kelsey Jig. The thickness of the ragging bed is found to be an extremely crucial parameter apart from the other process parameters such as rotational speed and pulsation frequency. A constant pulp density (25% solids) of the feed slurry was maintained in the study. The feed rate was also kept constant at 50 kg/hr dry solids. Silica sand of size -1.68+0.85 mm was used as ragging material to avoid the pegging of internal screen having an opening of 425 µm. The rotational speed was found to have significant effect on the depth of the ragging bed and its porosity, which influenced the separation performance considerably. Pulsation was identified as the key factor in stratifying the coal bed and defining the misplacement as well as ragging bed porosity, which influenced the mass yield and quality of the products. Beneficiation studies were carried out with rotational speed varying between 900-1000 rpm while pulsation frequency was kept within 850-925 rpm. In a single pass through the Kelsey Jig 7-8% (absolute) reduction in the ash content of the feed material was observed at more than 55% mass yield. High rotational speed, moderate pulsation, and low ragging bed depth favored good cleaning. A high bed depth was found to facilitate rejection of high ash materials. It was established that Kelsey Jig is effective in fine coal cleaning though a controlled operation is required in order to achieve superior performance. Keywords: enhanced gravity separator, g-force, separation performance, ragging material, coal beneficiation

Sep 1, 2012

By Erico Tabosa

The turbulence characteristics and measurement techniques for agitated tanks are well established for liquid and liquid-gas systems. However, the literature shows that the overall energy dissipation rate (related to turbulence) is affected not only by air addition, but also by the concentration of solids. Unfortunately, there are no reliable measurement techniques for characterizing turbulence in a three phase (liquid-solids-gas) environmental system, which is the case in a flotation cell. Therefore, the effect of turbulence on flotation kinetics is very much one of conjecture. The aim of this work was to develop a sensor to characterize the degree of velocity fluctuation, which is related to turbulence, in a flotation cell operating with slurry and air. This sensor comprises a piezoelectric film transducer that converts mechanical to electrical energy. Hence, when the sensor deflects backwards and forwards an AC voltage is created. Flotation studies carried out using this sensor in a 3m3 Metso RCS cell processing a copper sulphide ore showed a highly turbulent impeller zone with transition to a significantly less turbulent zone in the upper portion of the cell. The transition region moves as the cell operating variables are changed, for instance the impeller speed, impeller size, air rate and feed solids concentration. Keywords: mechanical flotation cell hydrodynamics, turbulence characterization

Sep 1, 2012

By ?. Kostadinov

Theoretical study of the behavior of grinding medium presented by TBP (tetraballpebs) was conducted by computer modeling of the position of grinding medium at different speeds and different drum fill factor. For the modeling were used known equations of motion derived for the ball load. Algorithm was created by SolidWorks software, allowing determination of center of gravity of the load in the mill and energy for grinding. These results were compared with similar results obtained by ball grinding medium. The capabilities of both grinding media are demonstrated by graphics under the following conditions: 1.Equal dimensions of the experimental model of the mill; 2.Equal mass of the grinding loads; 3.Comparison of grinding bodies with the same number, mass and density. Keywords: simulation, behavior, grinding medium, balls, tetraballpebs

Sep 1, 2012

By Carin Laubscher, Francis W. Petersen, Jaap P. Smit

Waste streams, such as acid mine drainage, are often characterised by low pH values and high concentrations of heavy metals, dissolved solids, calcium and sulphates. Although lime remediation effectively removes most of the heavy metals as hydroxides, it is less effective at lowering levels of sulphates. Various methods of removing sulphates from effluents exist, such as precipitation with lime, precipitation with barium salts, co-precipitation with calcium carbonate, reverse osmosis, and ion exchange. Mintek developed a chemical precipitation (SAVMIN) process to treat acid mine drainage, which entails the addition of lime to precipitate the metal hydroxides, and the subsequent formation (precipitation) of calcium sulphoaluminate or ettringite. The key to the viability of the new technology lies in the correct use, regeneration and recycling of Al(OH)3 used to precipitate the ettringite. The water produced by this process is suitable for disposal to watercourses or for agricultural, domestic or industrial consumption. No brines are produced as the salts are converted to solid hydroxides, gypsum and calcium carbonate. The technology has been tested on several different waters in pilot plant campaigns. Results obtained indicate that potable water can be produced (containing less than 200 mg/L sulphate and no heavy metals) as long as the monavalent ions (Na+, Cl-, etc.) are within limits.

Jan 1, 2003

By Matti Kongas, Kari Saloheimo, Antti Remes

"The paper studies the control performance of the flotation process as a function of the measurement accuracy and sampling frequency of an on-stream XRF analyzer, using a simple dynamic model. An additional aim is to assess how the economical result of a mineral flotation process depends on the quality of process control based on the on-line elemental assays.An on-stream XRF analyzer measures the concentrations of slurry lines in a continuous cycle from several process points. The control performance depends on the analytical accuracy and sampling frequency of the concentration measurement. With a long cycle time, the state of the process changes before a new measurement becomes available. With short measurement times the statistical variance of the counted X-ray pulses increases, increasing the random error in the analysis. In addition, the measurement accuracy depends on the concentration of the component to be measured from the slurry.To quantify the effect of analysis error and frequency to process control, a simple dynamic process model is created in the Matlab environment. Data from a copper flotation circuit is used as a test case. The process model comprises a first order reaction equation and the grade-recovery -relationship estimated from process data. The control was modeled using the control strategies implemented into a rule based advanced control system.The economical performance of the control was studied by calculating the overall net smelter return at various analyzer parameter combinations. The economical performance of the process declines strongly when the sampling cycle is increased. In studied case the sample measurement time did not have a significant effect on the results. The economical performance of the simulated process corresponds to an almost uncontrolled process when sampling cycles longer than 40 min are applied."

Jan 1, 2003

By S. M. Saghaeian

The studies on the product finer than 12 mm due to crushing and sizing plant of Gol-e-Gohar Iron Ore mine showed which this material contains significant amount of valuable iron minerals. Based on the carried out experimental studies on representative samples of fine hematite iron ore, a processing flow sheet was designed to upgrade iron content. This plant is known as first hematite iron ore enrichment plant in Iran which the dry medium intensity magnetic separators (with magnetic field intensity 4500 gauss and high gradient) has been used. The main objective of the plant is production of high iron product with iron content more than 61% and weight recovery more than 55% from the feed with iron content of 54%. In this plant, at first material are screened by a single deck screen (6mm), then oversize particles is separated at one stage by magnetic separator, while undersize ones at two stages. Based on the results of experimental tests, a final high iron product with iron content of 62.4% and weight recovery 63.9% can be achieved. It should mention which the iron content can be enhanced through increasing the speed of magnetic separators especially at the part of separation of finer iron ore.

Jan 1, 2014

By V. Sheikhzadeh, M. Saghaeian, R. Hejazi, M. Zare

High Pressure Grinding Roll (HPGR) plays a major role in increasing specific surface area of iron ore concentrate for producing pellet feed. HPGR grinding mechanism implies that material be compressed between the two rolls, therefore layer of material must be able to resist required pressure for achieving suitable grinding conditions. In this study for determining a simple relationship between material pressure resistance ability and HPGR main design parameters, piston press tests were performed on different iron ore concentrate samples along with HPGR Blaine increasing tests. Piston press tests results showed that by decreasing moisture content, material pressure resistance increased and in constant moisture content this parameter will change based on material specifications. HPGR Blaine increasing tests results showed that by decreasing moisture content, HPGR specific throughput and working gap increased and in constant moisture content this parameter will change based on material specifications. For all of the studied samples at worst condition, we got the results including: HPGR delta gap equal to zero, specific throughput lower than 200 ts/hm3.According to the tests results, HPGR Applicability Index (HAI) can be introduced at four different class types from 1 (weak) to 4 (excellent). This index determines achievable specific throughput and possibility of using HPGR according to material specifications, i.e. for HAI 1-4 the pressure resistance is <90, 90 to<125, 125 to <150 and = 150 bar, respectively. Similarly for HAI 1-4 specific throughput is <200, =200, =220 and =250, respectively. So based on design moisture content, if concentrate HAI is 3 or 4, HPGR is a correct choice. For HAI 2, HPGR can also be used. But for a material with HAI equal to 1, HPGR is not a good solution. As a result in order to apply HPGR for HAI 1, material condition such as moisture or slime content should be decreased.

Jan 1, 2018

By V. Ross

"The Upper Group 2 (UG2) reef in the Bushveld Complex in South Africa hosts an estimated 40% of the world’s Platinum Group Metal (PGM) resources. The processing of this ore via flotation poses two particular challenges: limiting the levels of chromite in the concentrate to reduce downstream smelting problems, and enhancing the recovery of ultrafine (typically -10 micron), liberated PGMs. Conventional ways of suppressing the entrained chromite, such as froth washing, is not effective in PGM operations, which are dominated by mechanical cells. The recovery of fine particles is hampered by low collision efficiencies with air bubbles, as well as oxidised surface layers especially in tailings operations. This paper documents the results of laboratory tests on a run-of-mine PGM UG2 ore, investigating the application of a pneumo-mechanical column (PMC) and its effect on PGM flotation and its selectivity with regard to chromite. A key feature of the device is the stage-wise release of aerated slurry from an agitated downcomer, thus creating conditions where the superficial velocity profiles of air and slurry change axially within the separation zone. This aids segregation of the silicates and chromite-rich fractions in the separation zone, concentrating the latter towards the bottom of the column and minimising its entrainment into the concentrate. Comparison of the performance of the PMC to that of mechanical laboratory cells under equivalent operating conditions showed improved PGM flotation kinetics and recovery. This was accompanied by a decrease in gangue recovery compared to the mechanical cells by more than 40%, thus doubling the final rougher concentrate grade from 50 to 100 g/t. Significantly, whilst the overall Cr2O3 recovery was reduced by more than 60%, the selectivity (PGM recovery vs Cr2O3 grade in the concentrate) was doubled.INTRODUCTIONThe Bushveld complex in the northern part of South Africa hosts the world’s largest reserves of Platinum Group Metals (PGMs), representing approximately 40% of the total PGE. It is characterised by three main PGM bearing reefs, namely Merensky, Upper Group 2 (UG2) and the Platreef. The Merensky and Platreef are dominated by silicates in the form of pyroxenites, and carry economically recoverable amounts of copper and nickel, in the form of chalcopyrite and pentlandite. The UG2 on the other hand is a chromitite ore with chromite as (ideally, FeO.Cr2O3) the most abundant gangue, often constituting more than 70% by mass with a PGM grade of around 4.5 g/t. Other key gangue minerals are pyroxene, feldspar and talc. The PGEs occur in a wide variety of minerals, with platinum and palladium sulphides typically accounting for about half of the total. Base metal sulphides such as chalcopyrite, pentlandite and pyrrhotite occur in only very minor amounts, accounting mostly for less than 0.1% by mass."

Jan 1, 2018

By Chen Jianhua, Shen Zhenchang, Zhang Ming, Chen Feifei

"With flotation cells scale-up, the performance of flotation cells is increasingly variated for short-coming and dead zones existing. The residence time distribution which shows the movement of tracers can assess the unexpected flows such as short circuit and dead zone in a flotation cell. In this paper, the residence time distribution of pilot flotation cell is investigated with CFD simulation. Based on the theoretical model, the short-coming probability and dead zone probability are quantitative. The ideal average residence time is similar with the actual average residence time. The mixing effect of the flotation cell approaches the ideal continuous stirred tank reactor. The operating parameters such as speed and feed velocity have complicated influence on residence time distribution. The research would be helpful to understanding flow in flotation cell and improving performances of flotation cell.INTRODUCTIONFroth flotation is a method which purifies minerals according to difference of physical and chemical surface characters of different mineral particles (Shen, Z., Chen J, 2012). Flotation cell is a key equipment for froth flotation method. The flotation cell performances have great influences on flotation index.It is difficult to evaluate flotation cell how to improve flotation procedure to complexity.The main flotation cell performances are aeration volume, air dispersion, solid suspension and residence time distribution, etc (Shen, Z., Lu, S., 2008). Residence time distribution is an important fluid hydrodynamics which could reveal the flow of pulp, mixing of particles and air bubbles. In the flotation cell, the ideal average residence time of pulp could obtain easily. But the fluid differential units would be different flow paths. The residence time of the fluid differential units is variation and would be longer or less than the average residence time. The residence time distribution would reveal the mixing effect and predict the not ideal flow in the flotation cell such as shorting cutting, dead zone, etc. As we know, the shorting cutting and dead zone would be decreased the real flotation time and it is disadvantage to better flotation effect, especially for large flotation cell. It is impossible to eliminate the not ideal flow totally. It is very important to reveal and decrease the shorting cutting and dead zone probability in the flotation cell."

Jan 1, 2018

By Chen Jianhua, Shen Zhenchang, Zhang Ming, Chen Feifei

"With flotation cells scale-up, the performance of flotation cells is increasingly variated for short-coming and dead zones existing. The residence time distribution which shows the movement of tracers can assess the unexpected flows such as short circuit and dead zone in a flotation cell. In this paper, the residence time distribution of pilot flotation cell is investigated with CFD simulation. Based on the theoretical model, the short-coming probability and dead zone probability are quantitative. The ideal average residence time is similar with the actual average residence time. The mixing effect of the flotation cell approaches the ideal continuous stirred tank reactor. The operating parameters such as speed and feed velocity have complicated influence on residence time distribution. The research would be helpful to understanding flow in flotation cell and improving performances of flotation cell.INTRODUCTION Froth flotation is a method which purifies minerals according to difference of physical and chemical surface characters of different mineral particles (Shen, Z., Chen J, 2012). Flotation cell is a key equipment for froth flotation method. The flotation cell performances have great influences on flotation index.It is difficult to evaluate flotation cell how to improve flotation procedure to complexity. The main flotation cell performances are aeration volume, air dispersion, solid suspension and residence time distribution, etc (Shen, Z., Lu, S., 2008). Residence time distribution is an important fluid hydrodynamics which could reveal the flow of pulp, mixing of particles and air bubbles. In the flotation cell, the ideal average residence time of pulp could obtain easily. But the fluid differential units would be different flow paths. The residence time of the fluid differential units is variation and would be longer or less than the average residence time. The residence time distribution would reveal the mixing effect and predict the not ideal flow in the flotation cell such as shorting cutting, dead zone, etc. As we know, the shorting cutting and dead zone would be decreased the real flotation time and it is disadvantage to better flotation effect, especially for large flotation cell. It is impossible to eliminate the not ideal flow totally. It is very important to reveal and decrease the shorting cutting and dead zone probability in the flotation cell."

Jan 1, 2018

By Juan B. Yianatos

"After almost 100 years, since the first commercial application began in Australia, flotation has shown an extraordinary growth and nearly 2 billion tons of ore per year are presently treated by flotation processes. During this time flotation has promoted a wide scope of research activities ranging from fundamental chemistry and hydrodynamic studies to studies of industrial operations. In general, fundamental studies have been mainly related to ideal situations. In recent years, however, large efforts have been focusing on achieving a better insight into the actual sub-processes provided by the development of new and more sophisticated instrumentation. Since the massive incorporation of flotation columns, around 15 years ago, a renewed interest in flotation fundamental studies, process modelling and new cell designs have been observed worldwide. The key role of the froth has been recognized as an independent and sometimes rate limiting process step. Thus, separation of pulp and froth process stages seems the most appropriate in terms of process modelling, diagnostic, design and scale-up purposes.In relation to flotation equipment development, until the middle of the 1970’s, only the sub-aeration mechanical cells were dominant. Since the 1980’s, the use of pneumatic cells and forced air mechanical cells has emerged strongly. Also, in the last decade, flotation equipment has shown a dramatic increase in size, reaching values of 200m3 in unitary mechanical cells and more than 300m3 in columns. The general feeling, however, is that, despite the great advance observed in terms of process knowledge, the mechanisms and principles of industrial flotation cells design and scale-up are still not fully understood.Advances in process instrumentation and control now in use allow for more efficient operations, both in metallurgical performance and savings in operating costs."

Jan 1, 2003

By S. M. Marr

"Water availability and water-related environmental impacts are now one of the most significant challenges facing primary production within the global minerals industry. Whereas the industry has, to a large degree, been able to demonstrate a collective response to greenhouse gas emissions and global energy demand, no such strategy exists for water. In part, this is because water quality and availability are regional issues, but also too because water quality cannot be defined by a single attribute, and extrapolation of any set of water quality indices to their associated environmental impact is no trivial matter. In design situations specifically, the situation is exacerbated by the fact that process engineers typically focus on site water management, and consent authorities are primarily in catchment level issues. As a result, an integrated approach to water management is difficult. This does not stem from an unwillingness by members of the professional team to engage with the total picture of water quality and availability, but principally from the fact that there is no common language through which to approach the problem.It is imperative for process engineers to extend their design system boundary, to reflect the geographic scales over which water impacts need to be quantified. It is not suggested that chemical engineers and metallurgists should become experts in geochemistry, hydrology and limnology. Rather, the challenge is to develop tools through which better communication of the relevant environmental impacts can be achieved.It has been estimated that 50% of the capital for new plants is devoted to handling wastes. The integration of mass exchange processes, adopting a life cycle analysis framework for considering environmental impacts and shifting the emphasis from effluent concentration to environmental impacts should be adopted in the framing of the design problem have been suggested as techniques of Environmentally Conscious Design. Shifting the focus from effluent concentrations and legislative requirements to evaluating the environmental impact is an important step towards improving the overall environmental performance of a process facility."

Jan 1, 2003

By Stuart Simpson

The biggest environmental challenge in mining is the management of mine tailings. Deep----sea tailings placement (DTSP) is practiced where the environmental impacts are predicted to be less than the impacts of tailings storage facilities on land. However, DSTP is often highly controversial owing to the challenges in assessing the impacts in deep water environments and potential long----term impacts beyond the proposed tailings footprint. It is well recognized that total contaminant concentrations are often poor predictors of the risk posed by contaminants in sediments. Metals within tailings are mostly present in highly mineralised forms that are typically much less bioavailable to organisms when compared to other common anthropogenic metals. Thus while metal concentrations in tailings can often appear alarmingly high, when compared to sediment quality guidelines (SQGs) used for assessing common urban and industrial impacts, the bioavailability is typically low. Although now well----embedded within risk----based sediment quality assessment frameworks, contaminant bioavailability is still often overlooked in the management of contaminated sediments. In this presentation, we assess and demonstrate the low bioavailability and chronic ecotoxicology of mineral----rich tailings to two benthic invertebrates, recognized for their sensitivity to metals: impairment of reproduction of the amphipod, Melita plumulosa, and the harpacticoid copepod, Nitocra spinipes. We demonstrate that the metal exposure from mine tailings is low when total concentrations are considered, and that the dose to the organism and toxic response observed is highly dependent on contaminant bioavailability. We discuss a range of approaches for the effective incorporation of metal bioavailability when applying SQGs or setting site-specific management limits for mine tailings in marine environments. While proposed DSTP operations require a high level of environmental scrutiny and monitoring during operation and post-closure, environmentally sustainable operations may be achieved when the bioavailable forms of metals within tailings remain below suitable management limits.

Jan 1, 2014

By S. S. Yu

In this paper, the producing process of using V2O3 as raw material to obtain vanadium nitride was analyzed through the means of thermodynamic. The analysis shows that conversion follows the principle of reduction step by step in the conversion process of V2O3. The temperature of the reaction system has prominent influence on the nitrogen content of products, and the reaction is very sensitive to temperature. As raising temperature, the fine grain structure of the nitrides is more evident, and the grain size of nitrides increases. At 1703K, the nitrogen content of the products tended to be constant after soaking over 3 hours.

Jan 1, 2014

By Anuttam Patra, Romain Bordes, Andreas Fredriksson, Tommy Karlkvist, Krister Holmberg, Kota Hanumantha Rao

The present investigation aims to develop and distinguish mineral specific reagents with two functional groups for use in flotation of calcium containing minerals. For this purpose, a series of dicarboxylate-based surfactants with varying length between the carboxylate groups (one, two or three methylene groups) were synthesized. As reference, a surfactant with the same alkyl chain length but with only one carboxylate group in the polar part was synthesized. The adsorption behavior of these new reagents on pure apatite and calcite mineral surfaces was studied using Hallimond tube flotation, FTIR and ? potential measurements. The relation between the adsorption behavior of a given surfactant on a specific mineral surface and its molecular structure over a range of concentration and pH values, as well as the region of maximum recovery were established. It was found that one of the reagents, with a specific distance between the carboxylate groups, was much more selective for a particular mineral surface than the other homologues synthesized. This selective adsorption of a given surfactant to a particular mineral surface relative to other mineral surfaces as evidenced in flotation studies is substantiated by ? potential and infra-red spectroscopy data.

Jan 1, 2014

By S. N. Shahcheraghi

Grinding is one of the most important and expensive steps in mineral processing allocating about 70% of the total energy in the plants. Nowadays, for optimizing the energy consumption in these equipments, the rock behavior and its size distribution during the crushing have been normally predicted using selection and breakage functions to be able to optimally model and design grinding circuits. For this purpose, the case of Miduk copper mine in Kerman province, Iran was studied. The samples were taken from primary ball mills feed and were subject to screen analysis to achieve uniform sizes. Then, selection and breakage functions were determined at the different grinding times in laboratorial ball mill. Finally, ore size distribution in different grinding times was estimated using MATLAB software

Sep 1, 2012

By Tom Liu

This paper is a fundamental study of bubble-particle collision efficiency in turbulent flows. A CFD-based microscale scheme for the prediction of turbulent bubble-particle collision efficiency in a 3D isotropic turbulent flow is developed, and in this way, turbulence effects on particle-bubble collision efficiency are taken into account for the first time. By comparing the computed results with experimental data from the literature, the CFD simulation is shown to correctly predict the bubble-particle collision efficiency in a quiescent environment. The CFD method was then applied to the investigation of bubble-particle collision efficiency in a turbulent flow, and the simulation results are shown to be qualitatively consistent with the real observations. The predicted collision efficiency can be used in a multiscale modelling scheme, which would account for all control variables in a flotation cell, such as impeller structure and tip speed, air nozzle structure and air flow rate This study indicates how microscale simulations of bubble and particle behaviours, coupled to macroscale CFD simulations of flotation cells, can provide a powerful tool predicting the flotation rate in a real flotation cell.

Jan 1, 2014

By Buks Kruger

"After the milling and flotation of the platinum bearing ore, the flotation concentrate is electrically smelted in 6-in-line electric arc furnaces and the resulting furnace matte treated in Peirce Smith converters to remove the iron sulphide. The iron free (less than 1% Fe) converter matte is then granulated and sent to the Base Metals- and Precious Metals Refineries for further processing.During the smelting and converting processes two distinct gas streams are produced.The Peirce Smith converter off gas contains 4% - 9% SO2 which is treated in a conventional Sulphuric Acid Plant to produce sulphuric acid (H2SO4).The electric furnace off gas contains 0.9% SO2 and was (until September 2002) vented through a 91 meter high stack to atmosphere.Off gasses which contain less than 3% SO2 is difficult to handle and quite a few processes had been developed over the years to cope with this gas. A broad spectrum of process suppliers and technology approaches is available and the different technologies can be divided into a few main approaches i.e.Scrubbing of the off gas with an alkaline solution to produce an environmentally friendly and stable waste product which can be discharged onto a tailings dam or permanent landfill site.Physical absorption of the SO2 into a chemical solution to produce high quality chemically pure process chemicals.Catalytic reaction of SO2 with O2 to produce SO3 which is absorbed in water to produce sulphuric acid of less than 90% strength.In October 2002 Impala Platinum commissioned a Sulfacid Plant at its Smelter in Rustenburg which recovers the SO2 from the electric furnace off gasses into a weak sulphuric acid solution.The Sulfacid Plant technology is widely used in the paint pigment industry. This is, however, the first application of the technology on electric furnace off gas.The furnace off gasses contains flue dust which is removed in electrostatic precipitators. The gas exiting the precipitators normally still contains between 40 mg/Nm3 and 60 mg/Nm3 dust and passes through a quench-scrubber before entering the reactors. The quench-scrubber cools the electric furnace offgas down from ± 200 °C to 60 °C and act as a final dust removal stage."

Jan 1, 2003

By Yimin Zhu, Dezhou Wei, Haijun Liang, Zhifu Zhou

Pyrite is one of sulfide minerals most widely distributed in the earth. During the flotating separation of metal sulfide and the floating desulfation of coal, it is often requaired to restrain pyrite. However, the result is not very satisfactory because of the little difference of floatability of minerals to be separated. The problem is extremely outstanding for the floating desulfation of coal. Researchers carried out a number of experiments with T. ferrooxidans (Yang et al, 2001; Zhou et al, 2000; Zhou et al, 2001; Wei et al, 2001) for an enhanced restraint to pyrite. The results showed that the T. ferrooxidans after being cultured works the best in restraining pyrite. After 10 min pretreatment, the removal rate of pyrite from coal is up to 80%~90%. The research results by Yuan Xin et al (Yuan et al, 2000) show that T. ferrooxidans can restrain effectively the floatability of pyrite and can reduce the recovery of pyrite from 95% to 8%. Though the restraining properties of T. ferrooxidans to pyrite have been proved by many tests and experiments, there are very limited reports on its restraining mechanism. Thus, a systematic experimental research is carried out in this paper.

Jan 1, 2003