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By F. Karakas

In this investigation, one of the most energy consuming stage of the cement manufacturing process, grinding stage, was studied. The aim of the study is to reduce the energy consumption. Optimum operating parameters were determined. Experimental studies were performed at three differ-ent stages. Grinding of limestone, clay and marl which are the main components of the cement, to approximately below 90 microns, was the first stage of the cement grinding. At this stage, effect of feed size and ball charge were investigated. At the second stage, the Bond work index of clinker and additives (slag, trass, limestone and gypsum) was found separately. After forming composite cement with clinker and additives, the Bond work index of this mixture was also determined, thus the results of separate grinding and grinding of mixture were compared. The Bond work index of mixture was found as 13.59 kWh/t, while the arithmetic mean of the Bond work index values of components was 14.90 kWh/t. Finally, clinker and additives (slag, trass, limestone and gypsum) were ground under the same conditions. At this stage, laboratory type of ball mill was used in order to understand grinding characteristics of the cement components. As a result of the experiments, it was found that energy consumption for the grinding will be lowered if the mills with 38 % ~ 40 % ball charge are used in the cement grinding. Moreover, grinding with mixture of clinker and additives gave better results than separate grinding of these components in terms of energy consumption.

Jan 1, 2014

By P. Braga, A. Chaves, S. França, A. Luz

"In Brazil, there are no official reserves of molybdenum, and the unofficial reserves are modest. Therefore, the molybdenum ore (molybdenite) produced as a co-product or by-product of emerald mining in the region of Campo Formoso, BA, has arisen as the only economic option. The flotation process is commonly used in Brazil for the recovery of molybdenite from emerald mining tailings, but it produces low-content molybdenite concentrates, thereby resulting in a product with low economic value. The molybdenite concentrate produced in Campo Formoso contains 83.5% MoS2 (50% Mo), which is less than the international standard product that contains > 90% MoS2 (54% Mo).This low value is due to the presence of talc, which is a naturally hydrophobic mineral that is also floated with the molybdenite during the flotation process. Separability studies were done in a Partridge-Smith cell using dextrin and quebracho as a molybdenite depressor in solution at different concentrations and pH values to produce a technical-grade concentrate (i.e., 90% MoS2). These basic studies were accompanied by measurements of the zeta potential and contact angle, which was determined by the capillary rise method. The results of these floatability studies were used in bench flotation tests, which were performed in a Denver laboratory flotation cell. A molybdenite concentrate of 93.4% MoS2 was obtained when dextrin was used at a concentration of 100 g/t."

Jan 1, 2014

By P. Fecko

The objective of the paper was application of bacterial leaching on two brown coal samples from locality Mine Druzba, seams Antonin and Josef (Sokolov brown coal basin, Czech republic). Based on the results of bacterial leaching and petrologic analyses of the given samples, it is possible to say that application of bacterial leaching gived good results. Applying bacterial leaching it is possible to remove from 34% to 47% of total sulphur and from 45% to 64% of pyritic sulphur from the coal.

Jan 1, 2014

By M. Kinnunen

Handling of municipal solid waste (MSW) and control of its potential resources is becoming increasingly important in modern society. The OECD (Organization for Economic Co-operation and Development) average on municipal waste produced in 2003 was that of around 570 kg per inhabitant. In European Union countries around half amount is of MSW landfilled. In Finland still 88% of MSW was landfilled in 2004. Since incineration reduces MSW volume significantly while producing heat energy, it has become one of the most common waste handling techniques. The shortcoming of incineration is however, that incinerated MSW is often not pre-sorted and it produces slags and ashes as side streams from which recovery of metals is difficult. This paper looks into possibilities of scrap metal recovery for recycling from municipal solid waste incineration (MSWI) bottom ash. In order to do that, a flow sheet of physical separation methods was developed and tested with Finnish rotary furnace MSWI bottom ash. In addition, an empirical model for estimation of the recoveries of scrap metals with physical separation methods for treatment of MSWI bottom ash was developed. According to the results of this study, for 1 Mt of incinerated MSW with 30% mass reduction, a minimum resource potential of 100 kt for magnetic metal scrap of roughly 24 % grade and about 19 kt of non-magnetic metal scrap of roughly 65 % grade. In other words, 57 kg magnetic scrap and 12 kg non-magnetic scrap per inhabitant at the mentioned grades, respectively. Although wide variations of parameters affect the MSWI bottom ash quality, it can be said that a considerable amount of metals is drained into MSWI bottom ash. Results of this study show that from MSWI bottom ash significant material streams metal scrap can be reintroduced into the resource cycle which would otherwise be lost.

Jan 1, 2014

By M. Vulkov

The paper is focused on the optimal selection of grinding medium for a drum mill. The decision-making is based on the fuzzy multiple attribute approach. One way to optimize the grinding process in a tumbling mill is associated with the development and testing a new shape of grinding body. Family of new grinding bodies ? spheroidal tetrahedrons (tetraballpebs) has been manufactured. Two types of spheroidal tetrahedrons and a classical ball (sphere) with one and the same weight are compared. A fuzzy entropy method to calculate the weight of the attributes is suggested. A grinding body which is the best approximation to the fuzzy formulated technological conditions is selected. Keywords: grinding, spheroidal tetrahedrons (tetraballpebs), balls, fuzzy sets

Sep 1, 2012

By Zhen Hu, Chenghang Wang, Jianjian Zou, Xiujuan Li, Hanwen Li, Tai Wang, Baoxu Song

A rare earth deposit in Sichuan, China is rich in wulfenite in addition to bastnaesite and barite, and the deposit has already adopted high intensity magnetic separation technique to pre-enrich the rare earth minerals, during which the wulfenite and barite have been left in the non-magnetic product. Because the chemical composition of wulfenite is only 24.17% Mo and 42.15% Pb, it is very hard to obtain qualified lead or molybdenum concentrates by physical separation process. To pre-concentrate the wulfenite, flotation has been first introduced, and by using 100g/t GY-7 as dispersant, 1500g/t CP-1 as depressant and 160g/t GY-4 as collector, a floatation concentrate assaying 15.52% Mo with a recovery of 86.12% was obtained. Then a leaching process was conducted by using 1.2mol/L Na2S as leaching agent, and molybdenum can be translated into sodium molybdate in the solution with a leaching recovery of 99%. To recover rare earth oxides (REO) and lead from the leaching residue, a magnetic separation process has been conducted. Above all, by the whole process, the molybdenum recovery reaches 86.16% in the sodium molybdate solution, and a lead concentrate assaying 54.59% Pb with recovery of 27.99% could be obtained.

Jan 1, 2014

By X. Q. Ma

The beneficiation test on low grade phosphate ore from a state of Russia is carried out. The rougher-cleaner ? re-cleaner system is used in the flotation process, The fineness of grind is 39.07% minus 200 mesh. The result indicates that concentrate containing 31.25% P2O5 can be obtained from the flotation feed assaying 6.18% P2O5, with 93.54% P2O5 recovery. The test result is also a guideline for further development of some currently operated phosphate beneficiation plants.

Jan 1, 2014

By Sergey S. Gudkov

In the current climate of changing the approach to mining and treatment of mineral resources, processing technologies are being developed that require little maintenance and are economically as well as ecologically sustainable. This may also involve the development of entirely new ways of ore processing. One promising approach is to use bioleaching for the pretreatment of gold refractory ores to cyanidation. Capital costs for vat bioleaching of concentrates and ores are very high and cannot be applied for small or medium-size deposits. IRGIREDMET JSC carried out bio heap leaching test work on refractory ore samples from three Russian deposits. Following this biological treatment a combination of flotation, vat bioleaching, and cyanidation are used to recover gold. After heap bioleaching, gold recovery was 75-80 per cent. It was found that efficiency of heap bioleaching process depends on ore feed size. High duration of this process is another feature and it lasts for about a year. This process can be also used for carbonates in the combination with other process during which acid generation occurs. The results of our studies have shown that this technology is amenable for refractory gold ores. Its introduction allows an increase gold recovery and to solve a number of environmental problems. Keywords: heap biooxidaton, the refractory of the ores, the degree of oxidation, arsenopyrite, pyrite, CIL

Sep 1, 2012

By C. B. Wu

This paper presents an analysis of comminution behavior of using cast iron segment (CIS) as fine grinding media with comparison to conventional steel ball. Grinding experiments utilize just one-size medium and mixed size media in laboratory were carried out and its efficiency is expected to be improved. The results show that no matter whether one-size medium or mixed size media employed, grinding efficiency of CIS media can be considerably equal to that of steel ball, on the other hand, grinding product by two kinds of media can conform to Robin-Rammler?s size characteristic curve and distribute in function of . )exp(100nbxy-= Comparing with steel ball, the milling capacity with CIS media could be increased up to about 8.6 percent, overcomminution decreased 3.96 in percentage and qualified size increased 3.98 in percentage in case of grinding fineness retained. At the same time, due to the improvement of grinding product size characteristic and its metal distribution characteristic, the grade and recovery of easy to separation size increased 0.24 in percentage and 6.47 in percentage respectively. Based on these results, the CIS media can be employed as novel fine medium for grinding process substituting for steel ball.

Jan 1, 2014

By Gulsen Tozsin, Ekrem Kalkan, Taskin Oztas, Elif Agirman Akturk, Ercument Koc, Ali Ihsan Arol

Marble wastes are generated by quarries (marble quarry waste-MQW) and processing plants (marble cutting waste-MCW). The large amount of marble wastes is becoming serious problem for industry and environment because of discarded into rivers and lagoons, without any treatment. Marble wastes can cause environmental problem and economic loss if the waste is not used. However, this type of wastes has a good potential to be used as an amendment for the neutralization of acid soils. In this study, MQW and MCW were applied to an acid soil at different rates and their effectiveness on neutralization was evaluated by a laboratory incubation test. The results showed that soil pH increased from 4.71 to 6.36 and 6.84 by applications of MCW and MQW, respectively. It was suggested that MQW and MCW could be used as soil amendments for the neutralization of acid soils, and thus the negative impact of marble wastes on the environment could be reduced.

Jan 1, 2014

By D. Gucbilmez

Three spiral concentrators having different geometries were compared in a chromite processing plant. They had different diameters, helix-cross sections and capacities. Two of the spiral concentrators were manufactured in China and one of them was manufactured in Australia. The tests were carried out in a closed circuit experimental setup by using a low grade chromite ore. The pulp densities kept the same during the operation, and the samples were taken simultaneously. The effects of the different positions of the splitters on separation and the feed rate were the parameters that were observed during the experiments. The performances of three spiral concentrators were found to be different. To clarify the effect of the particle size on the separation in spiral concentrators, the screening was applied to the feed. The samples were sieved from 75µm. The test results indicated that the separation performance decreased dramatically in very fine particles. Although fine particles caused some problems in spiral concentrators, fine grinding is required for this particular chromite ore for better liberation. A suitable method for the fine particles should be investigated for acceptable recovery.

Sep 1, 2012

By M. M. Kulkarni1

Kaolin clay is used as a filler and pigment in various applications such as paper, paint, rubber, plastics, adhesives, ink and ceramics etc. Major mineral content in crude kaolin clay is kaolinite along with some accessory minerals as quartz, hematite, mica, feldspar, anatase, rutile, illemnite etc. The Fe and Ti bearing minerals play very important role in determining quality of the kaolin, as these minerals impart yellow, pink or darker color to the white kaolin. Conventional beneficiation methods used in kaolin processing are de-gritting, classification and sodium dithionite bleaching, which improves the optical properties of kaolin, wherein reduction of color imparting constituents such as Fe2O3 and TiO2 is marginal. In the present study, these coloring impurities are separated using selective adsorption of water-soluble polymers. Degritted kaolin samples after passing through 45 micron sieve is used in the study for selective flocculation by polyacrylamide based polymers. The effect of pH, zeta potential, and polymer dose on the reduction of impurities is studied. Analytical tools such as XRF, XRD, SEM, and TEM techniques are utilized and results are discussed in detail.

Sep 1, 2012

In this paper High Pressure Grinding Rolls(HPGR) was utilized to pretreat CVRD southern specular hematite for enhancing the pelletization of the refractory hematite. The process parameters of HPGR, balling and firing were optimized, and the mechanism of HPGR was demonstrated by determining the surface activity by means of Blaine specific surface area tester, laser size analysis, scanning electron microscopy (SEM),X-ray diffraction (XRD), micro calorimeter and pelletability index. It is shown that the pelletization of the refractory hematite was greatly improved. The drop strength of green balls increases from 3.4 times to 13.6 times from 0.5m height while the bentonite dosage decreases from 2.2% to 1.3%.The compressive strength of roasted pellets also reaches 2500N/pellet. The mechanism of the pretreatment of CVRD southern specular hematite concentrates by HPGR is revealed that the surface activity is improved by an increases in specific surface area and the amount of micron size fractions, and higher lattice deformation and defects due to the fractures occurring inside particles during static pressure comminution, resulting in more wetting enthalpy, higher pelletability index and good property of roasting.

Jan 1, 2014

Mineral processing is an energy and water intensive activity. Mill comminution equipment usually has high energy requirements which necessitate extensive cooling to remove heat. Cooling requirements are typically 10% to 20% of the comminution energy. If there is an adequate supply of suitable water, open water-based cooling systems are the simplest, cheapest and most energy efficient cooling method available. This paper describes a method to determine the water demand for open water-based cooling systems at a plant and to determine whether the mine has sufficient water to meet that demand.

Jan 1, 2014

By R. C. Dunne

As ore grades of existing and new ore deposits continue to decrease there is ever increasing pressure to decrease operating costs to maintain profitabitabitiy at existing mine sites and for new projects. The accepted solution to this dilemma in most cases is to increase treatment rate, leading to a coarser grind, at the expense of marginal decreases in recovery. The recovery loss is usually associated with losses of liberated and composite coarse material. This paper will review the practice of coarse particle flotation, including the reagent chemistry, cell hydrodynamics, froth stability, entrainment and flotation cell design, all parameters important to the recovery of coarse liberated and composite particles. This will provide a better understanding of opportunities to improve the recovery of coarse particles. Some examples will be provided.

Sep 1, 2012

By Y. Q. Yang

Jig is a kind of conventional and old gravity concentration equipment, which is mainly used in the preconcentration of medium particle fractions of low-grade nonferrous metal ore. In the past ten years, studies on jigs have made a great progress on separation of coarse and fine particle fractions. At the same time, pneumatic jigs have been widely used in processing of nonferrous metal ore. In this paper, pilot test study and commercial operation for several kinds of jigs used in Dachang con-centrator has been introduced. Dachang mining area of GuangXi province is rich in mineral resources, where many minerals exhibit various complex properties. Many elements such as Sn, Pb, Sb, Zn, S, As, Cu, In, Ag, Gd, Ag, Ga, etc, were found in the run-of-mine ore (ROM). At present, Dachang concentrator produces tin concentrate, lead-antimony concentrate and zinc concentrate. Other valuable elements get enriched and recovered in above concentrates. Dachang Mine with a mining operation history more than sixty years will end its mission on the rich ore resource exploitation. At present, low grade ores are porcessed in the concentrator, and the concentrator begins to run at a loss upon processing the low-grade and refractory ore. Heavy medium cyclones were used in the concentrator for processing 20-4mm fraction, Gongge jigs for 4-2mm fraction, and cone concentrator combined with spiral concentrator to discard the tailings of -2mm fractions. In order to minimize overgrinding, table flotation was used to recover some liberated cassiterites in a complex processing technology. Therefore, the concentrator is difficult to manage. Many years studies have shown that heavy medium cyclones and spiral concentra-tors can be replaced by sawtooth shaped wave jigs to discard 50% tailings to improve the grade of feed. And the feed was divided into rich one and poor one to minimize overgrinding of valuable cassiterites with different grinding mills. In this case, the recovery of the valuable minerals can get improved and the flowsheet was simplified. Moreover, the concentrator begins to make profit with reduction of cost. At the same time, pollution in the concentrator gets reduced and the working condition gets improved too. Sawtooth shaped wave jig was used in Changpo concentrator for replacement of cone separators and spiral concentrators to discard the tailings of -4mm fraction, and the yield of discarded tailings got improved from 30% to 50%. Grades of tin, lead and zinc in the tailings are lowered from 0.15%, 0.12%, 0.7% to 0.06%, 0.05%, 0.4% respectively, with a loss reduction of tin, lead and zinc from11%, 9%, 10% to 7.5%, 6%, 5% respectively, corresponding to the increasement of recovery of tin, lead, zinc from 52%, 50%, 55% to 56%, 56%, 62% respectively. Cost of the concentrator for processing one-ton ROM was therefore dropped from RMB155.28 to RMB119.74. Changpo concentrator lost RMB2.5 million in 2003, but it made a profit of RMB0.92 million in 2006 after the innovations. Batac jig was used in Tongkeng concentrator to discard the coarse tailings at 20-4mm, with a discarded yield of 35%, and the grades of valuable minerals got improved with a recovery above 95% for tin, lead-antimony and zinc.

Jan 1, 2014

By C. Y. Wang

Anodic reaction mechanism of complicated antimony-lead concentrate in Slurry Electrolysis has been investigated by the anodic polarization curves determined under various conditions. The main reactions on the anode are the oxidation of FeCln (2-n), though the oxidation of jamesonite particle on the anode can occur during the whole process, it is less. With the help of mineralogy study and relevant tests, the leaching reaction mechanism of jamesonite and gudmundite during Slurry Electroly-sis has been ascertained also. Because of the oxidation reaction of FeCl3 produced by antimony-lead concentrate itself, the non-oxidation complex acid dissolution of jamesonite, the oxidation complex acid dissolution of gudmundite, and the oxidation of air carried by stirring, the leaching ratio of antimony reaches to about 35% when using HCl-NH4Cl solution to leach antimony-lead concentrate directly. So given the theoretical electric quantity, which to oxide antimony in Slurry Electrolysis, all of antimony, lead and iron, which contained in antimony-lead concentrate, are leached.

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 X. M. Chen

The selection of leach reagent mainly according to the ratio of useful mineral to gangue in mineral raw material and the structure of mineral raw material. Besides that the price of reagent, the capability of reagent decomposing mineral and its causticity on equipment is also supposed to be in regard. On common conditions, the scandium content in mineral raw material is low, even Sc concentrate of specimen-Yunnan rare earth ore which contain Sc used in this experiment only is 148 g/t. Moreover, in enlarging scale experiments the content of scandium in leach liquid is only 3.6g/t, meanwhile various and complicated impurity existing in it. At present, both domestic and abroad has succeed in enriching scandium from vitriol solution, while enriching scandium from hydrochloric acid only has been studied in some minority units, which is not reported to be practical in industry. Therefore, this item offer a new research issue on Sc?s extract, which is as well as the task of this research. Spectrum analysis, chemic component analysis and scandium content have been made in main mineral measurement on rare earth with Sc in the paper. Based on characters of sample, select hydrochloric acid, vitriol and nitric acid as leach reagent and make different blueprints to accomplish the experimental research about selecting leach reagent. In the aspect of rare earth leach scandium leach density is researched, leach liquid to solid rate, leach temperature, leach time, leach granule rate and leach solution. This experiment claims that in the optimal experimental ambience, leach rate of vitriol is 58.18%, the leach rate of nitric acid is 50.73% and the leach rate of hydrochloric acid is 59.34%. Among them, hydrochloric acid has the best effect, therefore this experiment choose it as the leach reagent.

Jan 1, 2014

By Nicolás Caussade

"The IMPC 2014 slogan "Optimizing Water and Energy Usage for Sustainable Mining" refers to the ever decreasing availability of fresh water and energy, which has turned out to be a crucial aspect in assuring the competitiveness of the mining sector in Chile and the Andes region in general. The concern for sustainability and the supply of water and energy is nowadays part of the top priorities of mining countries and communities. This is also the case for Antofagasta Minerals. Several years ago its mining group implemented an energy policy based on intelligent, strategic and sustainable management, in order to successfully face the challenges imposed by the market. It is called an intelligent policy because it intends to provide energy through a diversified range of sources, which includes the development of in-house alternatives. It is also a policy focused on efficient energy consumption and one that is strategic. Because it is in line with the characteristics of the mining activity, it is developed for the long term. Finally, what makes the policy sustainable is that it gives priority to energy usage from renewable resources and as such, the required capacities have been developed to generate innovative solutions that respond to the restrictions that characterize the industry today."

Jan 1, 2014