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By D. Chakraborty, Neeraj Kumar

"The study provides the comparative analysis of the performance of water only cyclones and hydrocyclone for iron ore fines processing at Joda Iron ore processing plant, Tata Steel. Joda iron ore deposits have higher proportion of kaolinite in the finer fractions and are meant to be separated with cyclones. The iron processing flowsheet of Joda comprises of water only cyclone for beneficiation of iron ore fines. Water only cyclones are used for the beneficiation of fines in the iron ore processing industry and have a larger cone angle compared to that of conventional hydrocyclones to enhance the density effect in the separation. They are aimed to achieve better product quality of underflow however; the desired result could not be achieved at the Joda processing plant. The water only cyclones were operating at the corrected cut-size of about 60 micron with an imperfection of 0.40 and water split to underflow was approximately 10%. The overall Fe recovery from the water only cyclones were 60%. Since the quality of fines produced from the water only cyclone couldn’t be improved, an attempt was made to process the fraction in the conventional hydrocyclone to achieve the desired product quality. The trial results indicated better product quality with the Fe recovery of 72% at corrected cut-size of 70 microns and imperfection of around 0.29. In view of above results it was recommended to replace the water only cyclones with hydrocyclones to achieve higher product quality of about 60% Fe content.INTRODUCTION Water only cyclones were installed at wet plant, Joda to process the classifier fines where the cyclone underflow is considered as concentrate and overflow is discarded as slime. Because of the lower capacity of the cyclones 30% of the classifier overflow was bypassed directly to thickener. Apart from this the quality of fines produced from the water only cyclone couldn’t be improved further hence an attempt was made to process the fraction in the conventional hydrocyclone to achieve the desired product quality and quantity. Hydrocyclone was installed at Joda after replacing stub-cyclone and came into operation on 23rd Aug’ 2017.The process variables of water only cyclones and hydrocyclones are tabulated below:"

Jan 1, 2018

By S. K. Kawatra, T. C. Eisele

"Coal-fired electrical power generation plants produce 56% of all the electricity in the U. S., burning approximately 860 million tons of coal annually. This results in production of 58 million tons of fly ash; 19 million tons of bottom ash and boiler slag, and 23 million tons of desulfurization sludges. These are a considerable disposal problem, and it would therefore be very valuable to be able to sell these residues and byproducts as useful materials, rather than paying to dispose of them in landfills. However, utilization rates are currently very low, below 32% even for the most thoroughly commercialized combustion byproduct (fly-ash). This poor utilization rate is a result of the high impurity content of combustion byproducts, which make them unsuitable for existing markets. The experiments described in this paper were therefore carried out to study the application of mineral processing techniques to upgrading combustion byproducts.Experiments were conducted to upgrade and purify low-grade combustion products to produce highgrade, readily saleable materials. A process was developed for removing unburned carbon from coal fly-ash by froth flotation, using reagents originally developed for flotation of oxidized coals. This technique could reduce the carbon content of fly-ashes containing up to 11.1% carbon to less than 2%. The froth product was sufficiently carbon-rich that the recovered carbon has value as fuel, or as low-grade activated charcoal.Fly ash was also examined as a binder for producing iron ore pellets, primarily as a substitute for bentonite. It was found that Class F fly ash in combination with an activator (calcium hydroxide) was an effective pellet binder at dosages comparable to the currently-used dosages of bentonite clay. While the flyash worked very well alone, tests in combination with bentonite showed that fly-ash/bentonite mixtures had significantly worse binding performance than either pure bentonite or pure fly-ash-based binder. This was determined to be due to the fact that bentonite and fly ash have profoundly different binding mechanisms, with fly-ash undergoing a pozzolanic chemical reaction while bentonite binds through a physical attachment process."

Jan 1, 2003

By Douglas Fuerstenau

"Comminution not only is the major energy cost in mineral processing but it also can limit the grade of ores that can economically be processed. Rittinger first postulated that the energy for comminution is proportional to the new surface produced. Because most of the strain energy needed to initiate and propagate cracks in particles cannot be recovered, researchers reported woefully low comminution efficiencies. Recognizing this, Schoenert proposed that the baseline for assessing comminution efficiency should be the mechanical energy needed to break single particles. After extensive single-particle studies, Schoenert turned to comminuting beds of particle in piston dies. Finding particle-bed comminution to be energy efficient, he had the brilliant conception of making the process continuous, namely his invention of the choke-fed high-pressure roll mill (HPGR). Practical comminution involves masses of particles, which can lead to energy efficiencies far less than that of single-particle breakage. A three-way classification of grinding modes in terms of the mobility of the particle mass provides the necessary insight into the low efficiency of different comminution machines: namely, single-particle breakage, confined particle-bed grinding (HPGR), and loose-bed grinding (ball mill). Examples are given for determining and comparing comminution efficiencies. The size distribution of comminuted products become self-similar, and a single parameter, the median size, can be used to quantify the extent of comminution. The reduction ratio, expressed in terms of the mean size of the feed and product, varies linearly with expended energy and the slope of such plots is a measure of the grindability of the mineral. This approach clearly gives the order of energy efficiency as single-particle > particle-bed > loose-bed comminution. HPGRs are more efficient at low reduction ratios but lose that advantage at higher reduction ratios. Extensive hybrid grinding experiments carried out with our instrumented ball mill and HPGR showed significant energy savings by first comminuting the material in the HPGR and followed by the ball mill. At Cerro Verde an industrial-scale hybrid HPGR/ball mill system is reported to have a 13 percent energy savings over a SAG mill/ball mill system."

Jan 1, 2014

By A. F. Usov

The paper is concerned with an analysis of the experience gained in development of special electro-technical installations applied in electric-pulse destruction of materials. A principle scheme of an electric electric-pulse installation is given, and electric circuit variants of its blocks made on various element bases are discussed. Also assessed are some ideas to further improve the technical and economic characteristics of the equipment.

Jan 1, 2014

By Z. H. Wang

The internal parameters of ball mill are very important in the grinding process and have significant impact on the grinding results. Accurate measurement of the internal parameters of ball mill is crucial and indispensable for optimization and control of grinding process. In this paper, a novel tri-sensor measurement method was used to measure the external signals (i.e., bearing pressure, sound intensity and power consumption) of ball mill. Mathematical models, which link the external signals of ball mill with its internal parameters, were established to predict the internal parameters of ball mill. Experimental results showed that the mathematical models could directly predict the internal parameters of ball mill once the external signals were obtained. The tri-sensor measurement method and the mathematical models proposed in this paper provided a new way and solid basis for optimization and control of ball milling.

Jan 1, 2014

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

By M. Saghaeian, R. Hejazi, M. Farahani, M. Dehghani, A. Tohry

"Wet tailing dams of iron ore processing plants typically contain a significant amount of valuable minerals. In more recent years, due to the increase in iron’s prices and technological innovations, as well as the low energy consumption which required for processing of materials from tailings, dams can consider as potential valuable deposits. However, the production of iron concentrate from tailings is usually complicated where the high moisture content of the material, the high clay content and the presence of chemicals of processing such as flocculants, acids and flotation reagents, all make materials highly sticky which can be easily swollen. In the present paper, the optimization of operational parameters to recover ultrafine hematite iron ore from the wet tailings dams of the Chador-malu iron ore mine was investigated. The optimization of operational parameters, showed that with modification of the washing unit components for slurry making, the challenge of constraints from feeding the plant could be overcome. To decrease the magnetite content in the tail stream of the medium intensity magnetic separation (MIMS) and subsequently increase the efficiency, the orifice of the cleaner tail flow exit pipe was changed from 7 inches to 3 inch and yoke angle changed from 14 to 8 degrees. These changes increased mass yield by 3% and decreased the magnetite content in the final tailings to 1.2%. By recirculating the cleaner SLons of final tailings within the circuit, the solid percentage of the feed to rougher SLons decreased to around 15%, and as a result the matrices were not overloaded that easily, and mass yield increased to about 13% from 7%. All the above mentioned optimizations were achieved without significantly affecting the concentrate Fe grade."

Jan 1, 2018

By I. D. Ustinov, V. A. Arsentyev, A. O. Mezenin, A. M. Gerasimov

"The solid mineral raw materials of the sediment deposits containing the argillaceous variations such as the coal and the potash ores are the most multi-tonnage solid minerals mined and processed in the territory of the Russian Federation. Both types of the deposits have relatively simple geology aspects with large and medium-sized solids and as a rule, the most often, with the regular bedding which are characterized by the fitchery thickness and the internal structure. Such deposits are very difficult for mining and processing. The thermal modification of this of ores allows changing the physico-chemical properties of its components in such a way that their further processing - grinding, separation, transportation and storage can be carried out without the use of process water or significantly reduces its consumption. The purpose of the present study is to increase the efficiency of the mineral processing containing the layered aluminum silicate by reducing their negative impact on the basic dressing processes, the separation of suspended matters and the storage of waste. INTRODUCTION Many deposits of minerals are associated with the presence of layered silicates such as the argil, mudstones, argillaceous slate - highly hydrophilic mineral varieties which have the ability to swell in the water. This ability to self-disperse creates the great difficulties both for the extraction and the processing of such ores. Since the dressing of most minerals is associated with the use of wet processes, where in contact with water the swelling layered silicates are dispersed to a particle size of less than 50 µm, but due to their high hydrophylic property they form bonds that promote the formation of so-called structured suspensions having increased viscosity. In this case the structured suspensions make it difficult to perform the separation operations as the classification, the gravity and magnetic separation, the flotation and thickening and filtration operations."

Jan 1, 2018

By E. T. Tuzcu

In this manuscript, a new approach for modeling the rate of grinding process is explained. A review about grinding rate definitions so far is given and the possible ultimate way for grinding modeling is given as modeling the rate based on energy spectra. The traditional/phenomenological approaches for modeling size distribution of grinding mills give their place to a new generation modeling technique. Developments in the computational methods and necessity to model product size distribution of large mills, larger than ball mill size, paved the way for this novel technique. The traditional grinding rate models are mostly based on the back calculated breakage parameters from the experimental data. However, direct modeling of breakage parameters and hence the prediction of size distribution of the grinding mills may become possible with this approach. The material breakage data and discrete element method (DEM) energy spectra are the main components of this approach. Albeit the focus in this study is on modeling of breakage rate under impact mode of breakage, the abrasion mode of breakage was also tested by carrying out abrasion tests. Impact mode of breakage was analyzed using ultra-fast load cell device (UFLC) and drop weight tester. Dry tumbling test was carried out for abrasion experiments. Obtained material breakage versus energy data are combined with the collision energy spectra to obtain the breakage rate function. In addition, the material breakage versus energy information from the tests is converted into breakage distribution function. The model was verified in a lab scale mill (90 cm diameter-15 cm length). 10 to 15 kg of limestone was ground using 50 mm steel ball at varying conditions, i.e., rpm, volume loading. It is shown that the proposed model predicts all (1, 2, 4 min.) grinding intervals for all experiments highly accurate.

Sep 1, 2012

By Paulo Castillo, Cesar Gomez, Jaime Alvarez

Operations using flotation to produce mineral concentrates require testing of frothers to characterize their ability to preserve bubble formation size and to build a stable froth. Many techniques have been proposed to measure parameters associated with these two roles. These techniques focus, in general, on only one of these roles and are based on special equipment operated at conditions quite different from those existing in industrial cells and columns. Both roles have been simultaneously characterized in a laboratory flotation column, but the requirements associated with the installation and operation of one of these units, are a serious limitation for its use on-site. A technique based on the use of a laboratory mechanical cell, a common piece of equipment in operations, will have wider application. Establishing the ability of a frother to control coalescence by preserving bubble formation size is done through bubble size measurements as a function of frother concentration. Froth build-up and stabilization is associated with the amount of water carried by bubbles into the froth layer, which has been demonstrated to correlate with the gas holdup in the collection zone. Procedures devised for determining the critical coalescence concentration (CCC) from measurements of bubble size as a function of frother concentration, and the gas holdup by collection of water displaced from the cell by the presence of bubbles at different frother concentrations, were tested. Three analytical-grade frothers were utilized: a straight-chain (1-heptanol) and a branched (MIBC) alcohol and a polyglycol (PPG425). The results obtained at a standard set of conditions, demonstrated consistent differences between these frothers, and the ranking from least to most effective for reducing bubble size or decreasing water drainage followed the same sequences found when more complex frother characterization techniques are used.

Jan 1, 2014

By P. S. Dash

With implementation of stringent environmental regulations, ultra clean coal technology development programs have gained significant importance worldwide. As far as Indian scenario is concerned, most of the coals present in India are of drift origin and low grade, containing high mineral matter varying from 15% to greater than 50%. The inorganic or ash constituents of Indian coals are finely disseminated through the organic or carbonaceous constituents so, that commonly used physical beneficiation techniques are of only limited value in affecting separation. Chemical processes involve addition of chemicals, which react with the mineral matter and allow its easy removal. The present study envisages the effect of aqueous alkali leaching followed by acid washing on the removal of mineral matter from two different captive coals of Tata Steel at elevated temperature and pressure. The experiments are conducted at desired conditions using a bench scale pressure reactor set up having proper data acquisition and control system. The research study revealed, that it is possible to reduce the ash content up to 70% by this method. The alkali content of the product clean coal does not increase whereas the silica and alumina content reduces by nearly 58% and 62% respectively. Significant reduction in the phosphorus content is observed after the acid treatment. The crucible swelling number of the feed coal improves after the treatment. The mechanism of demineralisation was evaluated by analyzing the coal samples before and after the alkali and acid treatment using scanning electron microscope (SEM). Because of the acidic nature of the silicates and aluminates, they dissolve into the NaOH solution and form sodalite. Sodalite is partially soluble in the alkali solution. The hydrates formed during alkali treatment are partially removed due to acid wash. This study in overall provides an insight into possible alternative methods of beneficiation for removal of ash from high ash Indian coals.

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 A. G. Bulaev

Biohydrometallurgical technologies based on activity of acidophilic microorganisms oxidizing ferrous iron, sulfur, and sulfide minerals are widely used to extract base and noble metals from sulfide ores and concentrates. As sulfide minerals oxidation is exothermic, industrial processes are usually preformed at 40–50°C. Moderate thermophiles predominate under these conditions. Most of moderately thermophilic acidophilic microorganisms that oxidize metal sulfide are mixotrophic, i.e., they use both organic nutrients and CO2 as carbon sources. Carbon availability is crucial for microbial activity and affects efficiency of biohydrometallurgical processes. Aeration with CO2-enriched air is often used to increase microbial activity in biooxidation reactors. Organic nutrients can be used as alternative carbon source for moderately thermophiles performing biooxidation of sulfide concentrates. We performed several experiments with different sulfide concentrates to study effects of organic carbon sources on biooxidation efficiency and demonstrated that application of such organic nutrients as yeast extract (YE) and molasses made it possible to increase biooxidation efficiency. For example, addition of 0.02% YE in the nutrient medium increased biooxidation rate of pyrite–arsenopyrite gold bearing and chalcopyrite concentrates in batch mode at 45°C. YE addition increased oxidation rate of sulfide sulfur and gold recovery level from 65 to 87% and from 73 to 81%, respectively. Similarly, YE addition increased copper extraction from 47 to 54%. At the same time, YE addition increased efficiency of biooxidation of pyrite–arsenopyrite gold bearing concentrate in continuous mode. Without YE addition, oxidation rates of pyrite and arsenopyrite were 65.7% and 94%, while gold extraction was 71%. YE addition (0.02%) made it possible to oxidize 74% and 95 % of pyrite and arsenopyrite and extract 78% of gold. Addition of molasses (0.02%) similarly affected biooxidation efficiency. Thus, addition of organic nutrients in nutrient media is a promising strategy for improvement of biohydrometallurgical processes.

Jan 1, 2018

By W. Y. Liu

A sulfate reducing bacteria strain (named SRB-A) is isolated from sanitary wastewater by using anaerobic technology of Hungate. The studies of physiological, biochemical and phylogenic of the isolated strain are carried out. The colonies of the strain are circle. Cells that are slightly curve, rod-shaped with the size of 1.0~3.0µm in length and 0.8~1.0µm in width. The optimum temperature for growth of the organism is 30~35°C. The optimum pH for growth is 7.0~7.2. Strain SRB-A can use sodium lactate, sodium citrate, sodium acetate, ethanol and acetone as electronic acceptor but can not use glycerol, glucose, sucrose and sodium oxatate. The isolated strain reduces sulfate, sulfide, sulfur, DSMO and FeCl3, then nitrate and nitrite can not be used. The strain has higher tolerance of NaCl, and the optimum growth occurs in the presence of 5%~8% (w/v) NaCl. The result of 16S rDNA sequence analysis indicates that the isolated strain SRB-A is the most similar to Desulfo-vibrio halophilus, and the level of the similarity was 98.4%. The isolated strain has a stronger ability to reduce sulfate, and the level of sulfate reduction reaches about 90% at pH 7 in the liquid medium. 0.6 to 0.8 is the optimum COD/SO42- in the medium for the isolated strain to show better ability to reduce sulfate. At pH 2.5 the level of removal of Cu2+ reaches 96.3%. Under the condition of pH 3.5, the level of removal of Zn2+ reaches 92.6%. When the value of pH reaches about 7, the Fe3+ is precipitated by the formation of Fe(OH)3, and Fe3+ is removed up to 89.4% at last.

Jan 1, 2014

By O. Kökkilic

This study covers the tests to develop separation process for production of clay and colemanite rich concentrates, and aims to serve the clay and colemanite concentrates extracted from the tailing dams to the industrial applications. For this purpose, samples from the tailing dams in Kestelek Boron Plant (Turkey) with an average B2O3 content of 8%~11 % were subjected to the investigations. The separation process of hydrocyclone--to make clear the way to obtain either clean clay or cole-manite--was initially discussed. Therefore, following the gentle scrubbing (to keep the bimodal size distribution between clay and colemanite) of the tailings to disperse the slurry, two alternative multistage hydrocyclone processes; allowing to recycling the overflows or underflows to concentrate clay and colemanite were respectively tested. As a result of the preliminary tests, the multistage hydrocyclone separation in direction to the clean colemanite concentrates (recycling the underflows) gave the better separation efficiencies. So, all the parameters such as apex and vortex finder diameters and feeding pressures were examined with the multistage hydrocyclone process allowing the recycling the underflows. The detailed multistage hydrocyclone separation process of the tailing dam wastes yielded with colemanite concentrates (approx. 12 % of the feed, w/w) with B2O3 content of 35.0 % and the clay concentrates (approx. 42 % of the feed, w/w) with B2O3 content of 2.1 %. Colemanite concentrates were found good enough either to re-feed in to the separation process or to keep upgrading for final product ready to use in Industry whereas the attempts on production of light bricks from clay concentrates has failed. But it is worth to point out that these clay concentrates can be used for agricultural purposes just in the form as it is.

Jan 1, 2014

By G. Deschênes

In the last 4 years, the high price of silver attracted more interest for improving its extraction. Metallic silver and silver minerals require a high concentration of cyanide and show slow leaching rates and poor extraction. This investigation determined the effects of dissolved oxygen, lead nitrate and a pretreatment on silver leaching from slurry containing quartz mixed with metallic silver and high purity acanthite. Stephanite, pyrargyrite and polybasite were also used in the study. The silver minerals were characterized by chemical assay, X-ray diffraction analysis (XRD), image analysis (MP-SEM-IPS) and electron microprobe analysis (EMPA). Increased dissolved oxygen of the slurry produced the fastest silver leaching kinetics. The leaching of silver from high purity acanthite was determined under various conditions and compared to a new process called ?CANMET Enhanced Leaching Process (CELP). For a slurry containing acanthite, a 23% improvement (from 76% to 99%) in silver extraction was obtained with the CELP. In presence of pyrargyrite and polybasite, silver extraction increased from 75% to 90% and 86% to 99% respectively using the CELP. No improvement was obtained for the slurry with stephanite (99% extraction in 72 hours). However, the sliver leaching rate was much faster with the CELP. XPS analysis of individual silver mineral particles showed that CELP leached surfaces were considerably more oxidized relative to the conventional cyanidation leached surfaces. Leaching of two gold/silver ores indicated that the efficiency of the CELP increased with the refractoriness of the sample. Gold extractions were comparable for the two technologies while silver extraction improved up to 5% (70g/t) for the CELP. The final leach solutions contained lower concentrations of copper, which consequently reduces the effluent treatment costs.

Jan 1, 2014

By Peter Ay, Harry Pempel, Satya Narra, Mike Müller, Jens Markowski

"Within the next few years major changes in mobility are expected. Increasing numbers of electric powered cars, electrobikes and E-Scooters define the transport sector. Recently lithium based traction batteries as storage medium have led into matrurity of series production combining high electrical efficiencies with low weights and compact dimensions. Due to the relatively young development with lithium batteries utilization, only few investigation were conducted regarding their recycling. Conventional battery recycling processes can not be applied due to differences in design and chemistry. So an automated disassembly and processing procedure for lithium traction batteries has been developed in the R/D-project ""Li-WERT"". Instead of complete smelting of the batteries without pretreatment, an automated disassembly and specific treatment of the material streams was realised, adjusted to the needs of the subsequent recovery technologies. A higher quality, with reduced expenses for the separation of fine-grained or fused material mixes, can be obtained for the individual components. The automated disassembly using an industrial robot significantly reduces dangers for the operating crew. The selective disassembly and beneficiation allows full recovery of the fractions. The batteries will be disassembled to cell level by the industrial robot. Anodes, cathodes, and separation layers are isolated and processed. The technology is designed, that no waste is generated for disposal. The pelletised cathode coating and the other separated metals (stainless steel, copper, aluminum) can be used in respective metallurgical plants. Circuit boards and plug contacts are also coveted secondary raw materials for reuse. The process is modular and offers high flexibility, e. g. for new battery types/ sizes by quick adjustment of the robot and tool change. Adaptation to other cathode materials (e. g. Li[FePO]) is possible. After finishing the R/D-project, a pilot plant for demontage was realised in 2013."

Jan 1, 2014

By A. Mainza, H. Hill, L. S. Bbosa

"Impact breakage is the most elementary size reduction mechanism in comminution devices. In comminution research, characterization of breakage is primarily concerned with the energy expended to cause it. The main challenges of this approach have been quantifying the actual energy requirements of impact breakage and developing mechanistic models to accurately describe the process. For engineering load analysis, fracture is characterized in terms of strengths such as yield stress and ultimate tensile stress, which govern the maximum loads specific materials can be subjected to before irreversible inelastic deformation and subsequently complete fracture occur. With this approach, the main challenge has been to elucidate the underlying mechanism, in the means that the load causes weaknesses in the material microstructure to act as sites for stress concentrations, leading to crack initiation, propagation and eventual failure. Studies dedicated to investigating particle fracture under impact loading have led to the development of several devices for conducting breakage characterization tests. These devices include the drop weight tester, split Hopkinson pressure bar, rotary breakage tester and the short impact load cell. All these have different particle loading and breakage methods, and thus can yield distinct information which can be compiled together to study a material and the nature of breakage. This work analyses the single impact breakage data obtained across the listed devices. A homogenous ore commonly known as blue stone is used for all breakage tests. The work is conducted using standard procedures specific to each device as closely as possible. Drop weight and rotary breakage tests were used to obtain hardness parameters based on an existing t10 breakage model, while split Hopkinson pressure bar and short impact load cell measurements provided properties based on conventional engineering load analysis. The results were used to highlight the significance of the loading geometry, impact mechanism and impulse on the extent of breakage."

Jan 1, 2018

By Sydney Mantsho, Toni Streczynski, Manuel Gonzalez

"In 2013, the commissioning of the MillStar Stabilisation and FloatStar Stabilisation and Optimisation controllers were completed at the Cerro Bayo Silver (Ag) mine in Patagonia, Chile. The MillStar control system has stabilised the feed to the SAG mill as well as the density at the discharge end of the SAG mill and ball mill. The FloatStar Stabilisation and Optimisation controllers have successfully stabilised and optimised the flotation circuit to ensure consistent product quality within desired specifications.The mill feed is controlled utilising the MillStar Solids Feed controller. Additionally, the solids to liquid ratio into the SAG mill was controlled utilising the Mill Inlet Ratio controller in conjunction with the Solids Feed controller. The discharge end of the milling process is a highly interactive and complex system. The use of a Robust Nonlinear Model Predicative Controller (RNMPC) was ideally suited to control this section of the process. On the Cerro Bayo milling circuit, the RNMPC was used to control the mill discharge sump level and the primary cyclone feed density to produce a more consistent feed to the flotation circuit.Three levels of the FloatStar control system were installed, for flotation stability, concentrate flow stability as well as grade optimisation. The Level Stabiliser was used to stabilise the level control on 6 flotation banks. The Flow Optimiser was commissioned on the Rougher, Scavenger and Cleaner concentrate sumps to stabilise concentrate flow from the flotation cells. The Grade Recovery Optimiser was commissioned on the Roughers section. A number of instrumentation challenges were identified which limited the overall benefit derived from the system. Once these were addressed, the performance was optimised. The overall benefit provided by the system was observed in terms of the improvements in Ag recovery."

Jan 1, 2014

By A. Y. Senchenko, Y. V. Kulikov

"The most common technique for selection of grinding equipment is the Bond method implying determination of a ball mill work index (BWi). The method is perfect for greenfield projects where a ball mill must be sized to grind an ore to 80% passing 75-100 µm. Finer grinding will require application of specific correction factors to a standard equation since initially the method was not designated for sizing of fine (minus 75 µm) grinding mills. Significant issues are related to selection of grinding equipment for treatment of originally fine materials when the standard procedure is not applicable. In 1984, Levin published his special technique titled as “A proposed test for the determination of the grindability of fine materials”, where he offered to use the standard Bond ball mill for determination of a specific grinding energy. However, this method did not meet with wide recognition. In 2017, Institute TOMS under guidance of JKMRC’s specialists performed a testwork aimed at verification of a new universal technique for determination of grindability of initially fine materials. An object was to test three aged tailings samples for the subsequent modelling of comminution circuit and evaluation of potential throughput of the existing ball mills with final grind size of ?80 passing 53 µm. In parallel with development of the universal approach, TOMS’ specialists carried out tests according to the Levin method in order to compare the data resulted from two methods. The results from lab ball mill testing on three products following the alternative test methods are presented in this paper along with the testing methodology and results analysis. Specific energy was calculated for regrinding of the materials to the required size. Difference of the examined methods and assessment of their applicability for sizing of full-scale equipment are explored."

Jan 1, 2018