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By T. Tsurata

The accumulation of thorium and/or uranium by various microorganisms from a solution containing thorium and/or uranium at pH 3.5 was examined. Among the species tested, a high accumulation ability for thorium was exhibited by strains of gram-positive bacteria, such as Bacillus megaterium, B. subtilis, Micrococcus luteus, Rhodococcus erythropolis, and actinomycetes, such as Streptomyces levoris. On the other hand, though uranium was accumulated in small amounts from the solution containing both elements by all these microorganisms, actinomycetes, such as S. flavoviridis and S. levoris had relatively high uranium accumulation abilities. In these high performance thorium- and uranium- accumulating microorganisms, S.levoris, which accumulated the largest amount of uranium from the solution containing only uranium at pH 3.5, could accumulate about 300 µmol thorium and 133 µmol uranium per gram dry wt. of microbial cells from a solution containing both thorium and uranium at pH 3.5. After this screening, uranium accumulation using microorganisms isolated from uranium mines, among which some strains of bacteria were found to possess an extremely high uranium accumulating ability. The microbial biomass may thus be considered for use as an accumulating agent for the removal and recovery of uranium that may be present in metallurgical effluents, mine tailings, seawater and other sources. Recently, hundreds of micro-organisms existing in uranium deposits located in North America, Australia, and Japan for their ability to accumulate large amounts of uranium, and found some new strains which accumulated large amounts of uranium, such as Lactobacillus and Bacillus sp. from Japanese and Arthrobacter and Bacillus sp. from the United States uranium deposits. These bacterial strains can accumulate about 2500 µmol uranium per gram dry wt. of microbial cells within one hour. These microbial cells can remove uranium from the uranium refining wastewater with a high efficiency. The accumulation of uranium from a solution (pH 5.8) by microorganisms contained Arthrobacter nicotianee, which is a similar strain mentioned above Arthrobacter sp., was examined. Among the 76 strains of 69 species tested (23 bacteria, 20 actinomycetes, 18 fungi, and 15 yeasts), high uranium accumulation ability was exhibited by strains of the bacteria, A. nicotianae, B. subtilis, and M. luteus. A. nicotianae cells, which showed the best performance, could accumulate about 698 mg uranium (2.58 mmol) per gram dry wt. of microbial cells.

Jan 1, 2014

By P. Vijay Kumar

Phosphate minerals are conventionally concentrated by flotation process using soap or soap- light diesel oil emulsion as collector. Some plants use detergents such as sodium petroleum sulfonate or alfa olefin sulfonate to enhance efficiency of soap flotation. It is reported that urea a known hydrotrope enhances flotation efficiency of soap as efficiently as alfa olefin sulfonate or linear alkyl benzene sulfonate at bench scale tests. In the present study tri sodium citrate also a known hydrotrope is tested as promoter in the flotation of phosphate mineral from Eshidiya ore.

Sep 1, 2012

The present study is devoted to improvement of the leaching efficiency during phosphorous removal from high phosphorous gravity-magnetic concentrate. Before leaching the concentrate has been subjected to roasting with the addition of either Ca(OH)2 or CaO. The oolitic iron ore is roasted at 900°C for one hour. This reflects in reaction between alkaline earth additive and quartz, aluminosilicates, phosphorus, and some other minor components of the gangue minerals. The application of leaching, physical separation, and wash out of salts has resulted in the decrease of phosphorus from 0.7 to 0.15 % and it is established that the major influencing factor is the concentration of acid and to a less extent duration of the leaching process. About two third of the phosphorus can be removed by roasting with 3 % CaO to hematite, coarse grinding to d50 0.3 mm, dry high intensity magnetic separation and leaching of the magnetic fraction with hydro-chloric or nitric acid.

Sep 1, 2012

By H. Z. Liu

An extra-refractory gold ore in China belongs to Carlin Type Gold Ore which is not only submicroscopic but also rich in arsenic and organic carbon. They have been proved that its floatability is not good enough and the gold in the ore could not be leached almost if it was not pretreated. The tests for the ore were carried out in accordance with flotation-concentrate preoxidation-cyanidation(or CIL) processes in order to exploit the mine. Two new depressants were discovered in the flotation tests and improved concentrate grades from about 20g/t to 32~50g/t. The methods of the concentrate preoxidation tests were alkaline atmospheric oxidation, acidic atmospheric oxidation, acidic pressure oxidation, roasting oxidation?biooxidation. The cyanidation tests after the concentrate preoxidation have proved the gold extraction of the pressure oxidation to be the highest(92.5%) and that of roasting secondary(89.3%). After fuller techno-economic comparison, it is suggested that the flotation-pressure oxidation or roasting-CIL process should be the most optimal for treating the ore. The gold recoveries of the ore were 83% for the pressure oxidation and 80% for the roasting respectively.

Jan 1, 2014

By Montaser S. EL Salmawy, Takahide Wakamatsu, Eishi Kusaka

"The effect of ethoxylation of long chain alcohols on the quartz and feldspar flotation behaviors was investigated for surfactants of the octylphenol polyoxyethylene family. The tests were carried out with an average of 7.5 (Triton X 114), 9.5 (Triton X 100), 30 (Triton X305), 40 (Triton X 405) and 70 (TritonX 705) oxyethylene units. Electrokinetic and flotation studies on quartz have shown that at low pH values, quartz could be floated with polyoxyethylene octytlphenols. The possible mode of adsorption of these nonionic surfactants may be suggested to be due to hydrogen bonding between the oxygen of ether and hydrogen in the free hydroxyl groups on quartz surface. It was anticipated that the selectivity between quartz and microcline would decrease as oxyethylenic chain length increases.Electrokinetic methods were used to elucidate the mechanism of surfactants adsorption and to correlate these findings with the optimum flotation conditions. The polymeric surfactants would reduce the negative values of zeta potential of quartz while the reverse is true for feldspar. After treatment of microcline with HCl, its electrokinetic behavior in the presence of Tritons X surfactants became similar to that of quartz.The obtained results would suggest that separation of quartz from feldspar using nonionic surfactants of octylphenoletoxylated alcohols having shorter oxyethylenic chain length at low pH could be achieved"

Jan 1, 2003

By S. Castro, L. Gutierrez

"Mining operations are often located in remote arid environments with limited access to fresh water. Shortage of fresh water in such cases makes it necessary to use seawater in mineral processing plants. Such plants treating Cu- Mo sulfide ores in seawater have been fully operational in Chile (e.g. Las Luces, Centinela). In many cases process waters used in commercial flotation plants (e.g. Mt Keith in Western Australia) are even more concentrated electrolyte solutions than seawater. This paper is an attempt at classification of the flotation operations carried out in process waters that are concentrated electrolyte solutions.INTRODUCTIONAccording to Gleick (1966), of the total Earth’ water resources 97.5% is in the oceans and ice caps, and thus only about 2.5% is fresh water. Shortage of fresh water in many parts of the world makes it necessary to use seawater in mineral processing operations. The existing commercial operations using seawater as well as recent research projects that deal not only with sulfide ores but also with apatite ores provide a lot of information that can now be generalized. The progress that has been made in this area is reviewed and based on this information an attempt is being made at classifying the flotation operations carried out in highly concentrated electrolyte process waters.SALT FLOTATIONFlotation in highly concentrated electrolyte solutions was studied by Klassen (Klassen, 1963). He reported that hydrophobic, bituminous coals, could float in salt solutions without addition of any other flotation agents. The process is referred to as salt flotation. Other inherently hyhrophobic minerals (e.g. talc, graphite, sulfur, etc.) were shown to behave similarly (Klassen and Mokrousov, 1963)As Figure 1 shows, some coals float quite well in solutions of Na2SO4, NaCl and NaNO3 (Klassen, 1963). While there are differences between the tested salts (explained by different foamabilities of these solutions) all the tests indicate that only bituminous coals float well in concentrated electrolyte solutions. 0.3 M solutions are quite sufficient to initiate a good and very fast flotation. If wettability of various coals is compared it becomes obvious that these well floating coals are very hydrophobic bituminous coals (Figure 2)."

Jan 1, 2018

By B. Q. Xiao

In surfactant flooding, surfactants added are often a mixture of the same type of molecules with different lengths of carbon chains. The relationship between a single, pure surfactant solution and crude oil is seldom studied. Additionally, up to now, alkylbenzene sulfonates are applied widely in surfactant flooding, such as Daqing oilfield, China. A factory producing alkylbenzene sulfonates will enlarge its yield to 20 000 tons per year over there. For the purposes of widening the alkylben-zene sulfonates? application, 16 kinds of pure alkylbenzene sulfonates were synthesized through Friedel-Crafts acylation and Wolff-Kishner reduction reactions, and the compounds? molecular structures were confirmed by 1HNMR and 13CNMR spectra. The factors affecting interfacial tension (IFT), such as, surfactant type, oil composition, electrolyte concentration, and alkali concentration were considered. The synthesized pure surfactants? critical micelle concentration (CMC) and optimal salinity were measured through interfacial tension technique. According to lab experiments results, heavy alkylbenzene sulfonate (2SY) was synthesized in magnifying scale in Jinzhou Wash Chemical Plant and the coretests were conducted using it. The results showed that the homemade heavy alkylbenzene sulfonate (2SY) flooding can improve oil displacement efficiency 20% more than water flooding at surfactant?s concentration from 0.05%(wt) to 0.2 %(wt).

Jan 1, 2014

By Liu Yong

A complex rare metal ore, containing various valuable elements is used in this study. The mineralogy results indicate that the mineral composition of the raw ore is complex, and there are more than thirty-eight kinds of minerals in the raw ore, and the elements, such as Nb, Ti, Fe, REO, Be etc, always form isomorphism relationship. The REO content of the raw ore is 0.45%, and the contents of other rare metals Nb, Ta, Ti and Zr are 0.33%, 0.02%, 0.93% and 2.00% respectively, and the main gangue elements are Si and Al, and their contents are 71.84% and 8.5% respectively. The beneficiation-metallurgy combination process of ?preconcentration-reduction and magnetic separation-acidification and leaching-precipitation? is used to treat the raw ore. The preconcentration of raw ore is realized through high intensity magnetic separation, and the magnetic field intensity is 1.0T, and the rough concentrate with 2.88% REO and 1.95% Nbresidue can be obtained, and the iron recovery is 92.83%, and the REO recovery is 95.87%, and the Nbresidue is treated by hydrometallurgy process of ?acidification-leaching-precipitation?, then the rare earth oxide, niobium concentrate and zircon-bearing residue can be obtained, and the REO recovery is 80.10% and the Nbresidue and the gangue obtained from the high intensity magnetic separation process is separated by gravity separation, and then the zirconium concentrate can be obtained. The indexes of the beneficiation-metallurgy combination process used to treat the complex rare metal ore are as follows. The REO content of the rare earth oxide is 92.58% and the recovery is 58.44%. The Nb2O5 and 27.42% TFe can be obtained. Iron in rough concentrates is removed after reduction and low intensity magnetic separation, then the iron powder with Fe content over 88% and nonmagnetic rare-metal 2O5 recovery is 94.77%. The rare-metal 2O5 recovery is 80.04%. The mixture of the zircon-bearing 2O5 content of niobium concentrate is 28.34% and the recovery is 54.02%. The ZrO2 content of zirconium concentrate is 28.43% and the recovery is 52.35%. The TFe of iron powder is 89.53% and the recovery is 78.13%. Keywords: rare metal ore, separation and extraction, beneficiation-metallurgy combination, comprehensive utilization

Sep 1, 2012

By Y. Y. Li, T. T. Yang, R. X. Zhou, Z. H. Shen

"Wetting theory is one of the basic theories of flotation. The effects of concentrations, carbon chain length and pH values of saturated fatty acid collectors (lauric acid, myristic acid, palmitic acid and stearic acid) on the surface wettability of collophanite and dolomite were investigated by measuring the contact angle with dynamic captive-bubble technique and calculating adhesion work of bubble-mineral. The results show that the contact angles both of collophanite and dolomite are higher with enhancement of hydrophobicity when pH value of 5~9. The contact angles both of collophanite and dolomite are reduced with improvement of surface hydrophilicity. When strong acid pH value of 2~4 or strong alkaline pH value of 10~13. The reasons for this are that the fatty acids mainly exist with insoluble RCOOH molecules in strong acid condition, and competitive adsorption of OH- and RCOO- in the mineral surface is formed in strong alkaline condition. With the increase of the collector concentration, the contact angles of the collophanite and the dolomite all first increase then decrease. The formation of hydrophilic micelles results in the decreasing of contact angles and enhancement of surface hydrophilicity opposite when the collector concentration exceeds CMC. The contact angles of the collophanite and dolomite and the WSG of the bubble adhesion increase, the hydrophobicity enhance with the increasing of carbon chains of saturated fatty acid from 12 to 18. The variation tendency for the adsorption quantity of collectors and floatability of collophanite and dolomite are in line with the change trend of contact angle basically. It shows that the wettability of solid-liquid-gas interface can be well characterized by the dynamic captive-bubble technique.INTRODUCTIONPhosphorite resources are the main raw material for producing phosphate fertilizer and producing phosphoric acid (Cao et al.,2005), which is an important strategic mineral resource. The useful minerals in calcareous-magnesium phosphate ore are collophanite, and the main gangue minerals are dolomite (SISH et al.,2003). The lattice ions of the phosphorite and dolomite are both Ca2+, their similar surface properties and similar floatability are the main reason for the flotation of calcareous-magnesium phosphate ore difficultly (Fang et al.,2011). Usually, fatty acid collectors are used for the flotation of calcareous-magnesium phosphate ore under acidic conditions by reversing flotation method to remove dolomite (ABOUZEID et al.,2009), or direct flotation is used to gather collophanite in the alkaline conditions (Gong et al.,2017). The flotation behavior of collophanite and dolomite affects the indexes of concentrate and flotation efficiency directly. Therefore, it is necessary to study the action mechanism and the flotation method of the collector with the phosphate rock and dolomite respectively (Moudgil et al.,1988; Hanna, et al.,1990)."

Jan 1, 2018

By V. F. Petrov, O. D. Khmelnitskaya, V. M. Lodeischikov

"The processing of copper gold ores is one of the major issues of gold-mining industry in the beginning of 21st century. In this case, application of ammoniacal cyanidation process for this type of mineral raw materials deserves special attention. Irgiredmet Institute has carried out a wide range of studies on ammoniacal cyanidation process and evaluated the possible commercial use of this process for Russian operating plants. Copper gold-bearing ore from a current Russian deposit was studied. The content of gold and copper in the ore is 9.4 g/t and 0.4%, respectively. Based on the results of preliminary test work, a flow sheet was developed. It included gravity concentration followed by cyanidation of the gravity tailings using CIP. The flow sheet provides sufficient total gold recovery (91.5%). However, this technology has disadvantages, such as high specific consumption of reagents: 4.5 kg/t NaCN and 13.5 kg/t Ca(OCl)2 the ore and the increased gold grade in the liquid phase of the tails slurry (0.2 g/t). In order to improve cyanidation process parameters, test work on gravity tails processing using ammoniacal cyanidation was carried out. After the test work was completed, ammoniacal cyanidation flow sheet for copper gold-bearing ores was developed. Leaching conditions were optimized using recycled process solutions. Recommendations on gold recovery from the solutions and tails detoxification are given. The proposed flow sheet provides 91.5% gold recovery. In this case, compared to the conventional option, the consumption of cyanide decreases by 3-4 times.INTRODUCTION The technology of precious metals recovery from gold-bearing ores is based on cyanidation. This accounts for up to 90% gold recovery and the significant portion of silver (Lodeischikov, 1999). However, there exists the category of so called refractory ores. They are not amenable to direct cyanidation (without using additional expensive processes), or they are characterized by low indices of metals recovery and high consumption of reagents. The latter also include copper gold ores. Their deposits can be found extensively both worldwide and in Russian Federation. A feature of these ores is that they contain not only gold but also copper. It is considered not only as a valuable component but also as a harmful mineral impurity that hinders gold cyanidation, gold precipitation from the solutions by cementation onto zinc dust and adsorption onto activated carbon (CIL, CIP-processes), detoxification of cyanide bearing effluents."

Jan 1, 2018

By M. D. Vilarinho, W. Xuan, F. Vasconcelos Guimarães

"This article summarises the efforts to reduce the energy consumption in grinding in a magnetite ore beneficiation plant. ArcelorMittal Kryvyi Rih ore beneficiation plant produces magnetite concentrate at 65% Fe and 8% SiO2, of which the D80 is approximately 44µm after three stages of grinding with ball mills and magnetic separation. Characterisation and laboratory scale bench tests performed on samples from the beneficiation plant indicate that the industrial flowsheet could be simplified. After the first stage of grinding and magnetic separation, a significant size fraction of the intermediate concentrate is already well liberated. Therefore, it can be directly concentrated in a second stage magnetic separation without further grinding. If a screen of 150µm size can be implemented after the first stage of grinding-magnetic separation, only the oversize of screening, representing 35% of the material, requires secondary and tertiary grinding and magnetic separation. The combined concentrate from the two fractions already meets the industrial specifications. This new route can provide the same final product, with fewer mills; it saves around 30% in energy consumption only in the grinding step without changing the main structures of the processing plant.INTRODUCTION Comminution, including crushing and grinding, is responsible for at least 40% of total energy usage in mining and mineral processing. This paper shows an example to reduce grinding cost, by changing the flow sheet design strategy in ArcelorMittal Kryvyi Rih (AMKR).AMKR is one of the most important mining and steel complexes in Krivoy Rog basin in Ukraine, which has been studied over 100 years because of mining of iron ores. The iron ores are associated to Banded Iron Formation of the Saksagan suite, with an average iron grade of around 36 percent Fe. The total thickness of the Krivoy Rog Supergroup reaches 5-6 km, whereas that of the iron-ore Saksagan Group comprises up to 1400 m. High-grade iron ore extends to more than 2,000 m below present surface"

Jan 1, 2018

By Zhang Yuejun, Feng Tianran, Shen Zhengchang, Han Dengfeng

"With continuous mining industry development and dressing plant scale expansion, flotation cell is developed towards to large scale and intelligence. Based on flotation cell scale-up theory and industrial practice, KYF-320 air-forced mechanical flotation cell with effective volume of 320m3 was successfully developed by Beijing General Research Institute of Mining and Metallurgy (BGRIMM) and adopted by China Gold Inner Mongolia Mining Co., Ltd, Luming project of China Railway Resource Group Co., Ltd, and Toromocho project of Chinalco in Peru. In this paper, the structure and technical characteristics of KYF-320 flotation cell are introduced, and the application of that equipment in China Gold Inner Mongolia Mining Co., LTD is demonstrated. The tank of KYF-320 flotation cell is cylinder-shaped, 8200mm in diameter and 7500mm high, with double froth lauders and large inclined angle cone bottom. 16 sets of KYF-320 flotation cells of which the processing capacity is 26,000,000 tons/a, are used in the second phase project of China Gold Inner Mongolia Mining Co., LTD. Their stable running shows the long life of impeller and stator and the power intensity (power consumption divided by effective volume of flotation cell) of KYF-320 flotation cell is only 0.73kW/m3 which is significantly less than that of small scale flotation cells. The industrial production obtains good results that the Cu grade of final concentrate of entire flotation circuit is 22.90% at the recovery of 86.73%, when Cu grade of feed is 0.35%, which indicates that KYF-320 flotation cell has good performance and can be widely used in large scale mine."

Jan 1, 2014

By Lilong Huang, Yuan Long, Li Shi, Guowang Zhang, Xiao Xiao

"Graphite is the key raw material of new carbon materials such as graphene and spherical graphite. The size and completeness of graphite flakes directly affect the performance of new carbonaceous materials.The research aims to increase the yield of large flake graphite by way of preventing the flake graphite from being damaged during the grinding process. A series of grinding and flotation studies on the flake graphite samples of Yichang in Hubei Province were carried out by vertical stirred mill . The damage coefficient L characterising the degree of graphite flake fractured and corresponding formula was proposed to determine the quality of the grinding and grinding of the flake graphite. The way the damage coefficient L of graphite flake would be affected if with different mill, different media material and size, stirrer speed were investigated. The test results show that vertical screw stirred mill helps the protection of large flake of graphite as well as the graphite liberation. When grinding to the same fineness, the damage coefficient L of graphite flake is 1.20 for vertical stirred mill, while the damage coefficient is 2.93 for ball mill. Minimum damage coefficient of graphite flake was obtained when using 6 mm polyurethane coated ball as grinding media, under the condition that rotation speed of the stirrer within the range of 100~130r/min. The grade of graphite in the concentrate floated from the ground product was 94.16%, the rate of recovery for graphite was 94.66%, and the content of +0.15mm was 54.83%.1 INTRODUCTION Flake graphite is a very important non-metallic mineral[1,2],and due to its special flake structure, the greater the scale and the higher the C grade, the value of its application is larger too. Therefore, in the grinding of graphite sorting process, We should minimize the destruction of graphite scales.. In this paper, graphite mine in Yichang, Hubei Province was used as the raw material for the study. Rough concentrate with C-grade of 36.49% was prepared by rough grinding and coarse separation. Then a series of grinding and flotation studies on the rough concentrate were carried out by vertical stirred mill , which aims to increase the yield of large flake graphite and to provide technical support for improving the beneficiation process of graphite ore."

Jan 1, 2018

By V. Panayotov, M. Panayotova

"Wastewater from ores processing is often polluted by molybdate and sulfate (SO42-) ions. Sorption is one of suitable methods for removing those pollutants when presenting in low concentrations. This work reports results on adsorption of sulfate and molybdate ions on metal modified (with barium - Ba and lead - Pb) and organic reagent modified (with Hexadecyl-trimethyl-ammonium bromide - HDTMA) clinoptilolite. Zeolite’s modification with Pb, Ba and HDTMA increases its uptake capacity with respect to Mo(VI) at pH 3, with the uptake capacity decreasing in the order CL-Pb > CL-HDTMA > CL-Ba. Lead-modified clinoptilolite shows high uptake with respect to Mo(VI) in acidic, neutral and slightly alkaline conditions. The presence of SO42- in concentrations twice higher than the amount of Mo(VI) do not interfere with the Mo(VI) removal by CL-Pb. Zeolite’s modification with Ba and Pb renders it able to immobilize SO42- from water in the pH range 3-9. Kinetics of the uptake process is best described by the pseudo-first order kinetic equation. Increasing the initial concentrations of Mo(VI) and SO42- increases the removed amount of pollutants. INTRODUCTION Wastewater from copper-molybdenum ores processing is often polluted by molybdate and sulfate ions. Molybdenum (Mo) migrates easily in water and consequently the Mo polluted areas could extend for hundreds and thousands of meters (Ryzhenko, 2010). Molybdate anion is the only Mo(VI) species in natural water, i.e. at pH > 6.0. Its median freshwater hazardous concentration affecting 5% of the species (HC 5.50%) is 38.2 mg Mo/L (De-Schamphelaere et al., 2010). The marine water chronic toxicity (HC 5.50%) is assessed at 5.74 mg Mo/L (Heijerick et al., 2012). The predicted no-effect concentrations (PNEC) are 12.7 mg Mo/L and 1.92 mg Mo/L correspondingly for freshwater and marine water (Heijerick et al., 2012a). When sulfates present in drinking water in excess of 250 mg/L they cause a cathartic action (especially in children) in the presence of sodium and magnesium, and when the concentration exceeds 600 mg/L, diarrhea. When sulfate-rich effluents are discharged into the environment, they may increase the acidity of water bodies and soils (Guimarães and Leão, 2014). Because of the adverse effects to human health and the environment, limits are set for SO42- concentrations in waters and wastewaters in the range of 250 / 500 mg/L."

Jan 1, 2018

By H. Ding

Calcium carbonate/Titanium dioxide composite, characterized by coating TiO2 on the surface of CaCO3 particles, is an important substitute for titanium dioxide. This paper studies preparation method of CaCO3/TiO2 ,composites based on mechano-chemical effects, measures its properties as a pigment, analyzes the binding form and interface reaction mechanism between CaCO3 and TiO2. Through single finely grinding of CaCO3, co-grinding of CaCO3 together with TiO2, and mecha-no-chemical effects produced in the course of grinding, CaCO3/TiO2 composites can be prepared successfully. Results indicate that grinding fineness of CaCO3, co-grinding time of CaCO3 and TiO2, the weight ratio of grinding media to mineral feeding, and the amount of TiO2 have much influence on the properties of CaCO3/TiO2 composites. CaCO3/TiO2 composites have the properties same as titanium dioxide pigment, oil adsorption and ultraviolet adsorption same as TiO2, and 90% of hiding power as that of TiO2. Wet grinding of CaCO3 causes the production of mechano-chemical effect and hydroxyl group, through which CaCO3 and TiO2 can be bonded together. Repulsion occurs between the particles of CaCO3 and the particles of TiO2, respectively, they are both in good dispersion. But attraction occurs between CaCO3 and TiO2. TiO2 particles are distributed evenly on the surface of CaCO3. Therefore, coating of TiO2 on the surface of CaCO3 particles and chemical bond between them make CaCO3/TiO2 compo-sites have pigment properties of Titanium.

Jan 1, 2014

By S. J. Lui

Sodium oleate was an effective diaspore collector, whereas chelate collector OL2 showed certain collecting power over diaspore and nonionic surfactant OL3 showed little collecting ability. Then experiments were carried out using sodium oleate as the main collector with the addition of OL2,OL3 to study the influences on diaspore flotation, it could be seen from the experiments that accelerants had a marked influence on the recovery of diaspore, which could be raised by 10%, and the addition sequence also affected the flotation behavior: the best results could be gained when the accelerants were mixed thoroughly before adding and the best ratio of collector OL1 and accelerant OL2, OL3 stood at 30:2:1. Based on the calculation of the ingredients in the sodium oleate solution, sodium oleate reacted with surface of the mineral and formed the acid-soap polymer [HOl?Ol-] when pH was about 9. Zeta potential test showed the accelerant promoted the absorption of collector on the mineral surface, which lowered zeta potential. As could be seen from surface tension experi-ments, the addition of accelerant OL3 lowered the CMC value of OL1 solution, which was equiva-lent to raise the power of the agents. Further Infrared Ray experiments showed the co-absorption of OL1 and OL2 make aluminum oleate on the mineral surface more stable. Up till now, the mixed reagents with sodium oleate as the main collector, combined with other two accelerants had been used in the Zhongzhou concentration plant, which is the first diaspore flotation plant in China.

Jan 1, 2014

By B. P. Baruah

A good deposit of high sulphur coals of tertiary origin is existent in North eastern region of India. These coals are known to have indifferent characteristics in comparison to other Indian coals. The general Physico-chemical characteristics are low ash and high volatile matter, calorific value and sulphur content. Sulphur in these coals (70-95% of organic) is mostly affixed to the structure of the coal. Owing to the stringent environmental regulations, the utilization of these coals has severe limitations due to high sulphur content. In the present investigation, sulphur incorporation in to these coals has been discussed along with possible organic sulphur functionalities. The various desulphurization techniques carried out for removing sulphur from these coals have been discussed. Two step oxidative desulphurization processes has been found to be most efficient for organic sulphur removal along with mineral matter and potential toxic elements. Keywords: oxidative desulfurization, potential toxic elements, sulfur incorporation

Sep 1, 2012

By R. S. Wang

The flotation of pyrite which be pretreated by electrochemical ways under external controlled voltages in different pH is explored. The floatability of pyrite is increased indistinctively after being pretreated in acidic and xanthate environment; Whereas, it is increased obviously between 400~800 millivolt in alkaline and xanthate condition. The reason for higher recovery of pyrite is that oxida-tion reaction, which results in S0 and S02, takes place on its surface, and that ethyl xanthate is oxi-dized into dixanthogen. In the meantime, the kinetics and mechanism is also studied.

Jan 1, 2014

By Sirish L. Shah

It is now common to have archival history of thousands of sensors sampled every second over long time. Yet we frequently have process engineers complain:??.We are drowning in data but starving for information??. How can these rich data sets be put to use? This paper addresses the issue of information and knowledge extraction from data with emphasis on process and performance monitoring including fault detection and isolation. Most of the major plant, factory, process, equipment and tool disruptions are avoidable, and yet preventable fault detection and diagnosis strategies are not the norm in most industries. It is not uncommon to see simple and preventable faults disrupt the operation of an entire integrated manufacturing facility. For example, faults such as malfunctioning sensors or actuators, inoperative alarm systems, poor controller tuning or configuration can render the most sophisticated control systems useless. Such disruptions can cost in the excess of $1 million per day and on the average they rob the plant of 7% of its annual capacity. Over the last decade the fields of multivariate statistics and data visualization and analysis methods have merged to develop powerful sensing and condition-based monitoring systems for predictive fault detection and diagnosis.These methods rely on the notion of sensor fusion whereby data from many sensors or units are combined with process information, such as physical connectivity of process units, to give a holistic picture of health of an integrated plant. Such methods are at a stage where these strategies are being implemented for off-line and on-line deployment. This article attempts to outline the field of sensor fusion - the application of signal processing methods, in the temporal as well as spectral domains, on a multitude and NOT singular sensor signals to detect incipient process abnormality before a catastrophic breakdown is likely to occur Keywords: Process analytics, process and performance monitoring, multivariate statistical analysis, sensor-fusion

Sep 1, 2012

By Y. C. Liu

Arsenic bearing copper-gold ores deposit have been found in most areas of China, especially in southwest. Due to the very closed association between arsenic, copper and gold, conventional flotation and cyanide leaching process may not give positive results. An arsenic bearing copper-gold ore in Sichuan province ,with gold grade of 10.12 g/t, 0.6% Cu and 0.14% As, is characterized by superfine grains with -40 microns fraction accounting for 70.9% and the gold enwrapped mainly by pyrite and tennanite accounts for 34.31%. Arsenic in this ore occurs in isomorphism, deposited in tetrahedrite. The ore was processed primarily in two stage flotation to get copper bearing gold concentrate and pyrite bearing gold concentrate respectively, and sequentially processed by leaching. Under the pressure of 300 KPa and 110~115 ?, the copper-gold concentrate was leached by an oxidizing and catalyzing leach agent then copper and gold were separated from each other in leach solution. The pyrite bearing gold concentrate was processed by cyanide leaching with the leach residue as sulfur product. The test results showed that copper recovery was up to 88.89%, gold recovery up to 89.18% and sulfur recovery up to 92.64%.

Jan 1, 2014