The understanding and application of autogenous (AG) and semi-autogenous (SAG) mills at various mines in China have been developing rapidly. A review of the application status of AG and SAG mills in metal mining operations in China is summarized in this paper. The SABC comminution circuit adopted for the first stage of Wushan copper-molybdenum mine project has been studied. Matching the equipment specification to the actual plant capacity, production instability and high energy consumption were the major issues at the Wushan SABC circuit. The operation status and energy distribution of each equipment were first analyzed and JKSimMet was then used to simulate the SABC circuit. Modifications and improvements including changing the grinding media filling ratio of SAG and ball mill, redesigning the pebble grate and adding pebble cabin have been performed based on the results obtained from simulations. A 36% increase in the designed mill throughput and a 2 kWh/t reduction in the energy consumption has been achieved through these modifications. It has been concluded that the optimization of SABC circuit using JKSimMet simulation can help increasing the throughput while reducing the energy consumption and can further be used for optimization of SABC comminution circuit at other mining operations in China.

Although the benefits of sensor-based sorting are well documented, the technology has not been widely applied. There are two main technical barriers that prevent the broader application, including limitations of sensors to accurately classify rocks and limited throughput capacities of the rock sorting platforms. Artificial intelligent approaches applied to sensor outputs has lead to improved discrimination. The integration of these sensors into the material-handling equipment has enabled sorting of bulk materials. The greatest beneficiaries of these breakthroughs are low-grade large tonnage deposits where sensor based grade control leads to greater resource utilization and more consistent and higher quality ore reporting to the mill leading to lower comminution costs and higher metallurgical recoveries. This paper presents the results of pilot scale bulk sorting studies and the operational improvements that are achieved.

Coming Soon

The algorithm for topological correction of lists of simplexes of different dimensions (TCLSDD) has been used to analyze the published methods for determining the internal diagonals in polyhedration of reciprocal systems. The errors were found in the polyhedration of the quinary system Li,K,Ca,Ba||F,WO4 with the five binary compounds. Advantages of the algorithm have been demonstrated in cases of a competition of internal secants, when all the possible (allowed) combinations of 1D, 2D, 3D and 4D simplexes are checking. The end result of polyhedration should satisfy the formulas relating the numbers of graph vertices and links between them with the numbers of 1D (internal diagonals), 2D (secant planes), 3D (tetrahedra) and 4D (pentatops) simplexes. TCLSDD gives a table that enumerates all the possible internal secant planes and tetrahedra. After analyzing the table, an unambiguous answer is given by the combinations of 2D, 3D and 4D simplexes that satisfy the resulting formulas. The algorithm allows one to determine all the variants of polyhedration and reveal the participation of competing internal diagonals in it. Of 15 pentatopes, into which the Li,K,Ca,Ba||F,WO4 system is partitioned, eight pentatopes were missed in the earlier study.
This work has been performed under the program of fundamental research SB RAS (project 0336-2014-0003) and was partially supported by the Russian Foundation for Basic Research (projects 14-08-00453, 15-43-04304).

The mining industry is well accustomed to taking the risks inherent in investing capital an orebody we can neither see or touch. Despite this, we, as an industry have often shied away from spending the upfront capital required to adequately de-risk a project. This has led to a recent history of start-ups which have failed to achieve their design capacity, and which require significant additional capital reinvestment early in their life. Diligent front end engineering, testing and design work is the best and lowest cost way to address these problems. In these underperforming projects, capital equipment was selected without sufficient information to design with confidence. Of critical import is an understanding of the geometallurgical units in the ore body, and their relative expected grinding and metallurgical performance in the selected circuits. Relevant to this, there now exists an advanced, integrated toolbox that has been under development for the past 25 years. This toolbox, if correctly used de-risks projects.
This presentation is intended to address the value which can be gained (or losses which can be avoided) through robust engineering. It will include a discussion of the evolution of industry best practices in design, for comminution and metallurgical recovery plants, corporate structure, and expectation differences for junior and senior mining companies, as observed during a 55 year career by John Starkey in mining and process engineering. Common mistakes and myths at the project engineering stage will be addressed with a focus on autogenous and semi-autogenous grinding, flotation, gold leaching, and iron ore metallurgical recovery circuit designs. Ultimately this presentation is intended to inform engineers, executives and investors about modern project engineering services available in the mining industry, and how mining companies can derive maximum value from their projects through careful front end engineering practices.

Bauxite supply has been a bottleneck problem with mass production of Chinese alumina industry in the decades, so nontraditional ore such as high-sulfur bauxite is being paid more and more attention. There is more than 0.56 billion tons of the ore in China, and the reserve is still increasing with further exploration. Yet the ore is seldom adopted or often abandoned because of the negative effect of the sulfur impurity on alumina production, so it is necessary to study on the desulfurization of high-sulfur bauxite to relax the shortage of bauxite supply in China. In this paper, current desulfurization methods were reviewed and future development trend was also predicted. Taking alumina production as a reference, current desulfurization methods of high-sulfur bauxite were divided into two groups. One was pretreatment desulfurization, and the other was process desulfurization. For roasting pretreatment of desulfurization, its technical economic effect should be reevaluated, and it might be a promising method of treating high-sulfur bauxite with organic and / or goethite impurities. For process desulfurization, if certain sulfur impurity in the sodium aluminate liquors was made to rapid and centralized precipitate before the seeded precipitation process, it would be very meaningful for the Bayer process to treat high-sulfur bauxite.

Although the effect of interfacial tension of liquid is often negligible at the macroscale, it plays an essential role in such areas as superhydrophobicity on rough surfaces, water walking of aquatic creatures and self-assembly of small particles or droplets. In this study, we investigate the migration and assembly of bubbles near the meniscus produced by a slender post with various cross sections.This topic actually is a fundamental subject for bubble fractionation in chemical engineering£¬the oil displacement in the steam-foam process and collection of oils from emulsified oil wastes in petroleum engineering.
The results show that the bubble always migrates to the solid wall of the post, although the cross section shape, material and tilt angle of the post are different. Especially, the final position of the bubble is not located at the singular point of the cross section, which is beyond what we have imagined. We simulate the morphology of the triple contact line via Surface Evolver, and then address the mechanism of bubble¡¯s migration from the viewpoint of force analysis and energy calculation. The factors governing the final position of the bubble are analyzed according to the scaling law. These obtained results cast new light on modulating the assembly of bubbles and small droplets by varying the material, geometric shape and posture of the post in water. These findings also have important implications for oil collection and oil displacement in petroleum engineering, drug delivery, design of microfluidic devices and chemical sensors.

Standard pyrometallurgical technologies of processing sulfide containing concentrates are accompanied by emission into the atmosphere the polluting tellurium, selenium and SiO2 gas. Catching of this gas and conversion into sulfuric acid is difficult and expensive problem because this requires PMG catalysts. Besides, sufficient part of rhenium is sublimated and lost. The paper describes the water-vapor processing of sulfide concentrates, particularly MoS2 in large scale plant (2.5 tons daily). Also, the features of conversion of SiO2 into Na2S and elemental sulfur are presented. The technology provides a high level of extraction of molybdenum (98.5%), rhenium (94%) and sulfur (98.4%) so it is efficient and environmentally friendly.

Grinding mills are the most often used communication equipment for size reduction and liberation purposes. The potentials of using speed as a key control parameter for mill optimization have not been fully studied in the industry. Variable Speed Drives (VSDs) offer flexible, responsive and easy control for SAG mill and ball mill operations. It provides an opportunity to improve and maximize the potential benefits. The potential benefits of using VSD drives for SAG and ball mill operations are presented in this paper. The effect of VSD compared to the fixed speed drives on the specific energy consumption, mill throughput, operating cost and overall grinding efficiency is also summarized in this paper.

In this paper the efficiency of non-thermal high-power (high-voltage) nanosecond electromagnetic pulses for the directional change of phase (functional and chemical) composition and technological properties of kimberlite rock-forming minerals (olivine, serpentine and calcite) and diamonds investigated using a complex of physical and chemical methods (XPS, analytical electron microscopy, atomic-force microscopy, microhardness measurement (Vickers indentation method), and the method of acid-base indicators adsorption). According to XPS and SEM-EDX analysis pulse, energy impacts causes a contravention of the dielectric-minerals surface microstructure forming area electric discharge traces and microcracks, that results softening of rock forming minerals and reduces their microhardness overall by 40-66%. According to our experimental data, the nanosecond high-voltage pulse pretreatment of diamond ore may increase the preservation (safety) of diamond crystals due to the kimberlite rock-forming minerals softening and more rapid release of diamonds in grinding process, caused by the reduction of time, that kimberlites presence in the mill.

The importance of potash for the plants and human growth is well established. Unfortunately, there are no potash resources like sylvite, carnallite or polyhalite in agricultural based country such as India. Therefore, India is meeting complete potash demand through import. An attempt has been made to extract potassium (K) values from silicate rocks such as feldspar and mica. Extensive characterization studies revealed that the sample contains orthoclase and muscovite as major potassium bearing mineral phases and K is locked in the host matrix. These rocks contain ~5-10% K2O and are subjected to different physical and chemical beneficiation processing and recovered only 10-12% values. Finally, a heat treated and activation process has been developed to extract about 90-99% K values at optimum conditions.

HPGR technology is considered as a prerequisite step for cement, diamond industry and is now making inroads in copper, gold and iron ores also. The use of HPGR depends mainly upon the cost considerations, downstream benefits and safe practice. However, the HPGR performance is predominantly dependent on its precise working practice which is indeed quite complex. This study reveals the performance of lab-scale HPGR and its comparison to industrial scale. The comminution principle for HPGRs is all about stressing a bed of particles so that each particle breaks its neighboring ones. HPGR modeling is more empirical rather than fundamental primarily due to a scarcity of lab-scale units. The slow adoption of HPGR in the mineral industry is due to uncertainties regarding the reliability of modeling-scale-up from a laboratory to commercial installations. In the present study, numerous experiments on different ores were conducted in a lab-scale HPGR and piston and die set up. The data reveals the effect of operating conditions on specific throughput, specific energy, and product size distribution. The data shows that rolls speed had a considerable effect on the fines generation, reduction ratio, and power draw since it has the direct effect on the throughput. It is observed that self-similar spectra of product size distributions of HPGR are independent of the operating conditions. The collected data shows that scale-up factors obtained in lab-scale HPGR and the industrial machine confirmed the applicability of lab-scale machines for tradeoff studies.

Design and operation of efficient ore preparation cycle require a detailed study of strength properties and characteristics of ore. There are many methods for estimation of grindability ore. Selection of procedure depends on method and approach to the design and type of projected scheme. Basic indexes and parameters of existing techniques are described in the article. This information allows to determine mechanical properties of ore, and gives a brief description. At present, tests to determine the energy indexes (the index definition by F. Bond and «Drop-weight» test) are among the most popular in the world of research to assess the strength properties of the ore in the laboratory. Combinations of crushing cycles, SAG, classification, and secondary grinding can be modeled. Requirements in the crushing energy are estimated by the results of the drop weight test, and power consumption for SAG may be determined by the results of the simulation. Modeling can also be used in the design of new cycles, check of different configurations of the scheme and improve of choice equipment. The database of laboratory research of grindability of various types of ores was collected for analysis and identification of mathematical dependencies between the parameters of drop weight tests and Bond indexes. Statistical analyzes were performed, graphs were constructed and equation of dependencies were obtained. These dependencies shown good convergence between the parameters, which characterizes the impact strength of (A ∙ b), the ability to abrasion (ta), and the ball grinding work index. This leads to a significant reduction in deadlines on phase of the study of characteristics of ores.

The beneficiation of the jig slimes waste from the South African Sishen mine was investigated with three techniques to upgrade it to concentrates suitable for iron making. The slimes were first characterized by chemical, particle size and iron deportment analyses. Three beneficiation routes were then explored: reverse flotation of the as-received slimes, pre-concentration by magnetic separation prior to reverse flotation and reverse flotation over the narrower size distribution. The as-received slimes were found to contain 44.0, 20.4 and 8.7% iron, silica and alumina respectively, with iron being more in the finer -25 µm fraction. The reverse flotation of the as-received slimes gave a concentrate assaying 51.2% iron and 17% silica, while the magnetic pre-concentration gave a concentrate with 64% iron and 5% silica, which after reverse flotation gave 66% iron and 2.7% silica. Flotation over narrower size for the -25 µm fraction from the pre-concentrated fraction finally gave a concentrate with 68 % iron and 1.6% silica. Magnetic pre-concentration followed by reverse flotation over narrow size distribution using 75 g/t of lilafloat D817M (collector) and 1000 g/t of corn starch (depressant) will produce pellet grade concentrate from this iron ore slimes resource.

Keywords:

Since the advent of sulphide flotation over a century ago, the processing of sulphide ores by grinding and flotation to concentrate the economic minerals into a low-bulk product suitable for smelting and refining has become common practice. This choice places the concentrator as a key lever in the business case of the mining company, however, the final tailings produced by the concentrator carry the highest and most variable amount of paymetal loss in the entire production chain of saleable metals (Cramer, 2001). For decades, the flotation process was operated by empirical heuristics and was limited by incomplete understanding. Quite often this metals loss to the final tailings could be considerably reduced with more appropriate flowsheet design and optimisation.
Since the 1980s, there has been much advancement in the technology used to diagnose the causes and find possible flowsheeting solutions to this problem, starting with the milestone work of Henley, 1983, in which he proposed the integration of geology, mineralogy, and mineral processing to synergise the processing information and develop more effective flowsheeting solutions. This was followed by the development and commercialisation of quantitative mineral measurement systems such as QEMSCAN, MLA and TIMA. Sampling practice, using the methods published by Pierre Gy in 1979, was also introduced for obvious reasons. There are now many publications on this modern integrated practice, which is called Process Mineralogy. In the best practice of Process Mineralogy, it is possible to quantify the process entitlement of performance. This gives a benchmark against which to compare existing plant performance and leads to an operations improvement programme that will close this performance gap.
Moving forward into the mining and milling of future orebodies, the challenge becomes more a matter of how to treat these difficult and complex ores, since the older, simpler and richer orebodies have already been discovered and treated. Additionally, the paymetal grades of these future orebodies are lower than was the case with the older ones, implying that more efficient processing will be necessary in order to profitably treat these future ores. It is thus critical in a greenfield project to establish the performance entitlement for the ore and to develop a flowsheet that will deliver that entitlement so as to assure the project of the maximum financial return on the investment.
This paper presents a summary of the modern toolbox and discusses some case studies in which successful flowsheeting solutions were found for both existing operations and greenfield projects.

In this research, Bond work index was used to evaluate the grinding energies of selected rock samples in order to predict their use as aggregate for road pavement. Samples of granite gneiss, porphyritic granite (Location1 i.e. L1), charnockitic rock and porphyritic granite (Location2 i.e. L2) from Itaji and Ikere in Ekiti State, Akure and Itaogbolu in Ondo State respectively; all in southwestern Nigeria were tested for hardness (aggregate crushing value, ACV and aggregate impact value, AIV). The Bond work index of these samples was also determined. The Bond work index of the granite gneiss was found to be 13.72kWh/t, that of the porphyritic granite (L2) 12.76kWh/t and that of the porphyritic granite (L1) and charnockitic rock were found to be 13.64kWh/t and 17.12kWh/t respectively. In order to predict aggregate quality, Bond work index (Wi) of samples were correlated with aggregate crushing value (Xacv) and aggregate impact value (Xaiv). Hence, the Bond work index values ranging between 0-7kWh/t, 7-10kWh/t, 10-14kWh/t, 14-18kWh/t and >18kWh/t are classified as ‘very easy’, ‘easy’, ‘medium’, ‘difficult’ and ‘very difficult’ respectively. It was shown that rock samples with work index values >10 kWh/t are qualified for use in flexible road pavement construction.

Quebec Northern Plan is one of the unique initiatives in the world for sustainable development of natural resources. Launched as one of the largest economic, social and environmental initiatives in 2011 it is underway today in Northern Quebec in the entire cycle of metal mining, mineral processing, extraction and refining. This article makes an analysis of this plan in terms of political, governing and financial frameworks as well as its implementation mechanisms comparing each aspect of it to sustainability principles.

The leaching efficiency of gold from some Saudi ores by the toxic cyanidation process is as low as 60-80%. Mining tailings of these ores contain considerable amounts of residual gold and toxic cyanide ion. These tailings are stored in massive ponds (tailing dam) containing considerable amounts of gold and pose environmental hazards. Utilization of these materials thus remains a challenging task for the gold ore industry in Saudi Arabia. This paper is aiming to recover gold from tailings of Al-Amar mine using the harmless thiosulfate process. Petrography of mineral constituents and XRD analysis showed that the rock samples consisted mainly of the following minerals in decreasing order of abundance: sphalerite (ZnS), chalcopyrite (CuFeS2), pyrite (FeS2) and galena (PbS). The elemental distribution map showed that gold is distributed mainly in sphalerite with gold content ranged from nil up to 0.04% in the tested sample. However, fine gold is found also in chalcopyrite and pyrite. Cyanidation of Carbon in Leach (CIL) feed samples gave about 60% extraction of gold at CN- ion concentration of 0.2% for 24 hours. We supposed that fine dispersion of gold in sulfide minerals could be the main reason for the limited gold recovery. Therefore, the encapsulated gold could be released after oxidation of sulfide minerals by calcination at open air. Chemical analysis of tailings showed that it contained 1.1 ppm gold. Maximum possible gold extraction reached 45% at 0.2 M ammonium thiosulfate (ATS), 0.3 M ammonium hydroxide (AH) with solid to liquid ratio of ½, and calcination for two hours at 400 ○C. The addition of Cu2+ or thiourea (TU) has no big influence on extraction efficiency. Replacing AH with TU gave almost similar results.

During manufacture of permanent magnets (Sm2Co7 magnets), around 20-40 percent of the slurry would be generated from the machining process. It is estimated that 20 tons of SmCo-containing slurry are produced annually. The SmCo-containing slurry contains 26.04% of samarium, 55.88% of cobalt and 12.12% of iron 4.39% of copper and 1.57% zirconium. Due to slightly oxidizing during the machining process, hydrometallurgy was chosen as a recovery method. The innovative recovery method includes drying, leaching, precipitation, purification and calcination. 6M nitrate acid was used as a leaching agent, leaching rate of all five elements were over 99%. Followed by oxidation and pH adjustment, iron(III) and cobalt(III) precipitate as iron hydroxide and cobalt hydroxide. After filtration, cupferron was further used to purify the leachate. Cupferron would precipitate with copper and zirconium as complex. After removing the cupferron-complex, oxalate acid was added to form samarium oxalate. Furthermore, calcination of samarium oxalate, samarium oxide was received. The recovery rate of samarium oxide is up to 95%, and the purity of samarium oxide is 99.5%.

In the process of resource utilization of high phosphorus iron ores, phosphorus should be removed first. Compared to other dephosphorization methods, selective leaching with acid has special advantages such as high de-phosphorizing efficiency, low iron loss and so on. However, a large amount of acidic wastewater containing phosphorus was produced after acid leaching. Therefore, the rational use of acidic wastewater and decrease of acid consumption is crucial to remove phosphorus by acid leaching. In this paper, the thermodynamics of the acid leaching was studied according to the existence form of mineral constituents. Then, crosscurrent acid leaching was employed to remove phosphorus from high phosphorus iron ore in Wushan Mountain and the changes in de-phosphorizing efficiency, iron loss and acid concentration was observed during the leaching. The results showed that the phosphorus in Wushan iron ore could be removed selectively by acid leaching. After three-stage crosscurrent leaching, the dephosphorization ratio exceeded 74% and the iron loss was under 2.1%. Meanwhile, the acid concentration was decreased to 0.65mol/l in leaching solution, which could be returned to selective leaching after precipitation of phosphorus and supplement of hydrochloric acid.

Bauxite ore is the main raw material for aluminum production, it is converted into alumina (Al2O3) to obtain a proper charge material for aluminum production in Hall-Heroult process. Bayer process is the main commercial alumina production method in which bauxite ore is first digested by NaOH at moderate hydrothermal conditions, followed by aluminum hydroxide (Al(OH)3) precipitation from the obtained sodium aluminate solution. Calcination of the hydroxide to alumina yields a high purity alumina feedstock for aluminum production. One of the main by-products of the Bayer process is red mud, which is separated from the bauxite solution after digestion and contains a significant amount of iron oxide. Red mud is one of the most important disposal materials in the world with no commercial use. Alternative sustainable process for bauxite treatment to alumina is Pedersen process, which was patented in the 1920s. This process was run for 40 years on a commercial scale before it was closed down due to the high cost of the alumina produced. The Pedersen process is more sustainable compared to Bayer process regarding lower CO2 emission and energy consumption. In this process, iron (the main impurity in bauxite) is removed from the ore through a smelting reduction process, which yields pig iron and high alumina containing slag. The slag is further hydrothermally treated to alumina through an economical process. In the present study, the carbothermic reduction of bauxite is studied at elevated temperatures through experimental work with lime addition as the flux. The effect of process temperature, slag chemistry, and type of carbon material on iron removal is studied. Moreover, the distribution of the elements such as Si, Ti, Al, Ca, Mn, and so forth is investigated under different process conditions. The chemical, physical, and microstructural properties of the produced slags are also studied.

In this paper, Electrochemical analysis technology was utilized to study the behavior of pyrite under different system. The result of cyclic voltammetry showed that the process of pyrite anode reaction consists of multi-step. Through the redox potential information obtained from the cyclic voltammetry curve, consolidating the intermediate reaction process, pyrite was oxidized to ferric ion and sulfate finally. Studies on Tafel polarization curve under acidic, ferric ion and inoculation condition showed that pyrite was more susceptible to be oxidized and oxidation rate was faster in presence of bacteria. The corrosion current was 1.41uA under acidic condition, the corrosion current was 123.49 uA under ferric ion (c(Fe3+)=1.0g¡¤L-1) condition and the corrosion current was up to 142.40 uA. The polarization resistance was up to 1.84¡A106 ¦¸¡¤cm-2 under acidic condition, and the polarization resistance was respectively 7.59¡A104 ¦¸¡¤cm-2 and 2.30¡A104 ¦¸¡¤cm-2 under ferric ion and inoculation condition. The leaching test of pyrite in presence and absence of bacteria showed that the presence of bacteria could significantly improve the leaching rate of pyrite. The leaching rate of pyrite was 12.94% under acidic condition after eighteen days, the leaching rate was 36.01% under ferric ion. However, the leaching rate of pyrite was up to 89.46% in presence of bacteria, which was 6.91 times higher than the one without bacteria.

Alumina (Al2O3) is the main material used for the aluminum production, which is originated from bauxite ore through hydrothermal processes. Although bauxite conversion to alumina can be done through a few competitive processes, the main commercial process is still the well-known Bayer process. This process has specific environmental challenges and in more than a century the mining and aluminum industry could not overcome them. For instance, red mud disposal that is produced in the digestion step of the bauxite is high in iron oxide and also contains a significant amount of aluminum oxide. However, there has not been successful approaches in Bayer process for preventing red mud production, and even there is not still a promising method for its consumption in other industry. In the present research work, different processes for alumina production from bauxite are studied and compared with regard to sustainability; the integrated processes, their alumina yield, energy consumption, waste materials, and so on are evaluated and discussed.

The mill liners are one of the most crucial component in a grinding mill. The metal magnetic mill liners have got a wide application in Chinese mines since 1993 especially for iron ore. With the development of large scale non-ferrous mining industry, the application of magnetic liners has been limited. The Nano Steel Magnetic liner (NSML) is a magnetic liner recently developed to cope with the shortcomings of magnetic liners and has been successfully installed at Erdenet copper mine in Mongolia successfully. The new liner assembly has additional 12 months of service life and approximately 6.5% of increased mill throughput with ~50 hours less reline downtime.

The mineral processing research of gold ore with arsenic, carbon, fine disseminated has been the focus of the work of researchers these years, various methods and technology for Refractory gold ore have been studied , each one has its own merits, the ore roasting method is one of the world recognized can effectively solve this kind of ore, but more the main Chinese reported in the experimental research, in practice, few successful examples, from researching, investment,production, technical innovation, experience from trial production to the entire process of mature, Guizhou Jin Xing company has gone through a tortuous road of success .Using cyanidation process after ore roasting ,the smelting plant of the daily processing 1000t raw ore in Guizhou Jin Xing gold company,has been running for many years , the production index is stable, the problem of environmental emissions, waste water, and waste residue, is completely solved, comprehensive recovery of gold at a rate of 80%, the Steady increase in economic benefits.

Grinding is a major contributor to the cost of processing fine grained ores, (e.g. ores containing copper, nickel, zinc, gold and platinum). At least two stages of grinding are used and the second stage is typically ball-milling. The cost of ball wear is similar to the cost of power. Pebbles are normally allowed to discharge from ports in the primary mill, so that crushing of a recycled stream can be applied, to control the charge level in the primary mill. It is envisaged that recycled pebbles (with a size range of say 19 to 75 mm), which are normally crushed, can be more usefully used in combination with balls in the secondary mill(s). Mixtures of steel balls and pebbles were tested using a 0.57m diameter mill and the results were compared to ball-milling in the same mill. Power was measured on-line and the pebble wear rate and product size distribution were measured after each test. Various proportions of pebbles were used and a 25 percent pebble content (by volume), was found to be the optimum. <br />The results were very encouraging, with power being reduced by 10 to 18 percent, due to a reduction in the density of the mill charge, and an implied saving in ball consumption was 25 percent. It was also noted that there was no change in the product size distribution and the grinding capacity. Up to a pebble content of 25 percent, the grinding capacity was maintained, but it reduced progressively after that point, implying the need for a larger mill. <br />Most of the tests were designed to produce a finished product, equivalent to the size distribution of a cyclone overflow. Preliminary tests were done using silicate pebbles (from a gold mine) and quartz sand. Further tests were done using pebbles from a platinum mine and a sample of the feed to a ball-mill at the mine. Some of the latter tests simulated closed-circuit grinding, where the mill product was relatively coarse, requiring classification and a recycle of coarse material. <br />The pebble consumption at the optimum proportion of pebbles was relatively low (about 7 percent of ore throughput). However, it is envisaged that pebble storage would be needed in an operating circuit, to allow for periods when the ore has a low proportion of competent rock. The effects of withdrawing pebbles from a primary mill are discussed, including the saving of power for pebble crushing and an estimated reduction in ball addition to the primary SAG mill. <br />It is concluded that the use of a ball-pebble mixture in secondary mills can reduce costs significantly, without compromising throughput. There is potential to use existing ball-mills and operators can revert to ball-milling at times when there is a shortage of competent pebbles. Further tests in a continuous pilot-plant or plant are recommended to confirm the findings.

For the ore with a high content of mud and water, traditional three stages crushing with one closed circuit caused ore transfer difficult, especially in Ailaoshan area, Yunnan province, where just has the rainy and dry season.The dust is rising in the dry season and the ore flow is unsmooth in rain season, these influence mine production seriously. After transformed the crushing & ball milling to semi-autogenous grinding & ball milling, the environment of workshop improved greatly, the equipment running efficiency and the throughput of concentrator increased, and the production and economic benefits also improved a lot. The transformation practice is worth use for reference.

Artana Mine is part of Trepca mining company, which is known as one of the biggest Lead and Zinc ore recourses in Southeast Europe. The groundwater’s flowing from the Artana mine, in contact with sulphide minerals of Pb and Zn, but as well because of the composition of heavy metals and toxic substances such as Pb, Zn, Cd, As, etc., which have sensitive acidity, cause environmental pollution. The acidity of the mine effluents was calculated to 1024 mg CaCO3/L. This causes a permanent threat for stream waters, wells but as well the flow of cross-border rivers.
Being that levels of toxic elements exceeding the prevailing environmental limits,treatment of the polluted water from the mine, has been identified as a high priority from the Ministry of Environment in Kosovo as it is part of the strategy for environmental protection.
To prevent environmental pollution with these toxic metals, an appropriate chemical treatment with proper advanced technology should be conducted, using equipment and material for the neutralization and sedimentation which will provide the parameters set by European standards for waters category. Water after treatment with this process can be recycled and used in the ore flotation processes in order to produce concentrates.

« Back To Technical Program