Search Documents

By M. Abdollahy

In this paper, the hydrophobicity of chalcopyrite particles produced with different laboratory mills has been studied; different grinding mechanism in themills made some changes in particles shape, Image Analysis (IA) method was used to determine the shape properties of chalcopyrite particles which are ground by a laboratory ball mill, rod mill and ceramic ball mill. The shape characters are stated in terms of shape factors such as circularity, convexity, roundness and regularity factor. Hallimond tube was used to float chalcopyrite particles followed by determination of critical surface tension of particles, this parameter used as a criterion to study the wetting behavior of chalcopyrite particles. The correlation between shape properties and critical surface tension of chalcopyrite particles showed that the hydrophobicity of chalcopyrite was affected by the shape. Investigations showed that the circular, round and more convex particles that produced with ceramic ball mill had lower hydrophobicity with higher critical surface tension (?c). The results also showed that the hydrophobicity of particles ground by ball and rod mills increased with the decrease of roundness, circularity, convexity and regularity factor of particles. Keywords: chalcopyrite, particle morphology, flotation, image analysis system, micro flotation method, hydrophobicity, shape properties

Sep 1, 2012

By A. Vidyadhar

Using pure quartz and hematite minerals, the adsorption mechanism of mixed cationic/anionic reagent schemes was investigated through Hallimond flotation studies. The flotation response of quartz and hematite independently with cationic and anionic collectors as well as with mixed cationic/anionic collector systems is assessed. The flotation response as a function of pH and collector concentration was investigated. The single mineral flotation tests in the presence of anionic collectors, quartz does not respond to flotation, but the C12 amine flotation of quartz was observed to be pH and concentration dependent. It was observed that hematite flotation recovery is maximum at acidic pH with sodium dodecyl sulphate (SDS), neutral pH with oleate, and at basic pH about 9.5 with C12 amine. Flotation results with both quartz and hematite indicate an increased adsorption of cationic collector in the presence of anionic collector apart from its own co-adsorption. The incorporation of oleate in between C12 amine molecules decreases the electrostatic head-head repulsion and thereby increasing the adsorption of C12 amine due to attractive tail-tail hydrophobic bonds, besides forming a closely packed adsorbed layer enhancing the hydrophobicity. The increase in oleate concentration beyond C12 amine concentration leads to the formation of soluble C12 amine-oleate complex / precipitate and the adsorption of these species decreased the flotation since the alkyl chains are in chaotical orientation with a conceivable number of head groups directing towards the solution phase. Keywords: quartz, hematite, adsorption, mixed collector system, flotation, zeta-potential

Sep 1, 2012

By I. Kairyakov

The present paper is about the restoration of the molybdenum production in the floatation plant of Ellatzite-Med AD in Bulgaria. The process, based on a working design, includes the construction of a new floatation molybdenum section in the existing molybdenum department of the Floatation Plant using the so called Vemco inert-gas floatation machines, made especially for the molybdenum floatation. While in the ordinary floatation machines, block impellers create suspension of the air, sucked from the atmosphere with the slime particles of the concentrate, which creates conditions for oxidizing the reagent, Vemco inert-gas floatation machines are covered with hermetic lids and the air inside the chamber is used. The technology, suggested by Geotechkoper Ltd. for making the working project, employs special machines from Dor Olliver Aimco, suitable specifically for molybdenum floatation in order to reduce the oxidizing of the reagent sodium hydrosulphate. Also the transport of the chamber product is done in hermetic conditions as the molybdenum flotation is done in two floatation rows and refining operations 3 to 8 are placed in the second row. Thus in the basic molybdenum floatation together with the first and second refining operations, which are hermetically closed, an ambient condition with low content of oxygen is created, that is about 8% for oxygen and about 92% of nitrogen, in which the oxidizing process is extremely reduced. This in turn results in reducing the consumption of the reagent depressor ? sodium hydrosulphate. In that way there is an improvement of the economical indices of the molybdenum production.

Jan 1, 2014

By H. B. Zhou

The process of bioleaching marmatite using moderately thermophilic bacteria has been studied in this research by comparing marmatite leaching performance of mesophilic bacteria and moderately thermophilic bacteria and valuating the effect of venting capacity on marmatite leaching performance of moderately thermophilic bacteria and the effect of pulp densities on marmatite leaching performance of moderately thermophilic bacteria. The results show that moderately thermophilic bacteria have more advantages over mesophilic bacteria in bioleaching marmatite. Aeration agitation can improve the transfer of O2 and CO2 in solution and promote the growth of bacteria and therefore, enhance the leaching efficiency. With the increase of pulp density, the total leaching amount of valuable metals increased, however, the extraction efficiency decreased due to many rea-sons, like increasing shear force that results in poorly growth condition for bacteria, etc.

Jan 1, 2014

By Jia Ma, Lu-De Qiang, Zhi-Chao Liu, Chun-Feng Li, Guang Li, Bao-Bin Tang

"At present, research on the surface chemical properties of uranium minerals is very scanty, which restricts the research progress of uranium ore flotation process research. The research aimed at exploring the surface characteristics of two common uranium minerals and providing basis for flotation process to enrich uranium minerals in ore. This paper selected pitchblende and uraninite as the object of study, which are widely distributed in uranium deposits. We chose out the pure minerals of pitchblende and uraninite from different ores collected from different uranium deposits. By means of Zeta potential test and X-ray photoelectron spectroscopy (XPS) test, a preliminary study on surface characteristics of the pure minerals of pitchblende and uraninite was conducted. And the significance of the change of Zeta potential, the elements composition and valence state on the minerals surface for flotation was discussed. The research shows that, the Zeta potentials of pitchblende and uraninite in pure water are negative mainly when the pH value varies from 2 to 11, which maybe a result of the difference of ionization capacity between two kinds of oxy-compounds on the surface of minerals. On the surface of pitchblende and uraninite, the metal elements are mainly U, Th and Pb. U is mainly in the form of UO2, Th is mainly in the form of ThO2, and Pb is mainly in the form of Pb and PbO. Based on the surface characteristics of pitchblende and uraninite, we can select process and reagents appropriately in uranium ore flotation.INTRODUCTION Globally, the major challenges associated with exploitation of low grade ores are about finding economically feasible processes for reducing the mass of gangue minerals (Filippov et al., 2012). Among the beneficiation technologies of low grade uranium ores with complex minerals assemblage, flotation is the common process which is used to reduce production cost and eliminate the acid-consuming minerals (Li et al., 2016; Liu et al., 2015)."

Jan 1, 2018

As a leading global company in the mining sector, we are committed to sustainable development. To this end, we invest in the responsible, integrated management of economic, environmental and social issues. Vale?s objective is for our businesses to produce local, regional and global prosperity, enabling the construction of a positive legacy throughout the lifecycle of our activities. This covers everything from talking with stakeholders and preventing failures to complying with legislation, paying constant attention to environmental issues and respecting ethics in business. Keywords: sustainable development

Sep 1, 2012

By W. S. Eu

Thermal treatment of mineral ores can initiate thermal phase transformations which can affect either their activation or deactivation, subsequently influencing their ability to dissolve in a leaching reagent. The formation of rutile and hematite from ilmenite minerals, for example, has been suggested to occur through a series of reduction and segregation reactions. This process has been used in beneficiating low-grade weathered ilmenite ores to higher grade rutile. Despite decades of re-search, the mechanism of this process is not well understood, because dissolved intermediates are poorly crystalline and are difficult to quantify, with the exception of the final rutile products. Previous studies have shown that disrupted intermediate phases, by thermal treatment, are most susceptible to reagent attack and can often demonstrate ?activation? effects. In this study, synchrotron based X-ray diffraction method was used to investigate in-situ and in real-time the transformation of ilmenite minerals to rutile and hematite during calcination. The rate of formation and disappearance of specific Bragg peaks during the reaction and thermal decomposition of the mineral were used to derive an understanding of the solid-state reactions. The effects of the mineral transformation were validated by laboratory based batch calcination and leaching in sulphuric acid. The results suggest that transformation of major mineral phases occurs within of specific window of operation and thermal treatment appears to influence the extent of activation and leachability of ilmenite minerals.

Jan 1, 2014

By P. Raghavan1

Reverse froth flotation experiments were carried out in the laboratory using two different types of kaolins for the separation and removal of coloring titanoferrous impurities from cryo-filtered clay after subjecting to high shear pre-treatment. This high shear pre-treatment consists of high shear agitation of a high solids clay slurry with the dispersant (high shear dispersion, HSD) followed by high shear agitation with the collector (high shear conditioning, HSC). After this pretreatment, the slurry is diluted and reverse flotation is carried out. One sample is from, Gujarat, India (Mamuara clay, ?MC?) while the 2nd sample is from Amberg, Germany (AKW clay, ?AC?). While MC consisted of 89% particles below 2µm and analyzed 1.06% of TiO2 and 0.29% Fe2O3 and measured a brightness of 83.4 %ISO, the corresponding values for AC are 67% below 2µm, 0.3% of TiO2? 0.49% Fe2O3 and 83.4 %ISO. The flotation performance is found to be greatly influenced by the conditions of high shear treatment. Important variables are HSD intensity (rpm), HSD time, HSC intensity (rpm), HSC time, HSD/HSC time ratio, ?HSD+HSC? total time etc. Higher shear intensities favor both the impurity liberation and collection. For both clays, it could be shown that impurity removal increases as total pretreatment time (?HSD +HSC? total time) increases up to a certain limit. For MC, the HSD time was only half or less than that of HSC time, while for AC, HSD time is at least twice (or more) than HSC time which is just an opposite manifestation. This is believed to be due to the striking differences between these two clays. Most importantly, the shear frequency is found more influential than the shear rate for the overall flotation performance for both clays. Interestingly, at high shear frequencies, i.e., when a stirrer with more number of teeth on the rotor is used, the ?HSD+HSC? total time is greatly reduced. Again, increased shear frequency helps to reduce flotation time and significantly improves flotation performance. At optimum conditions, product titania reduced to 0.35% for MC whereas the same reduced to 0.13% for AC. The product of flotation of MC measured 85%ISO brightness while that of AC measured84.6%ISO thus enhancing the value of the final product. It could also be established that the high shear pre-treatment shows better flotation performance than that due to collector dosage. Keywords: high shear dispersion, high shear conditioning, titanoferrous impurities, shear rate, shear frequency, brightness, clay recovery, Mamuara clay, AKW clay

Sep 1, 2012

By Qidong Zhang, Yongsheng Song, Wenjuan Li, Guiying Zhou, Kun Song

"Molybdenum is a very important rare mineral resources, which exists largely in oxidized ores and sulphide ores in nature. About 99% of metallic molybdenum comes from molybdenite. The talcose molybdenum resources are abundant but the resources utilization is low, because the talc is naturally hydrophobic and the floatability of talc is similar with molybdenite, which lead to difficult separation by flotation. Talc is easy entry into concentrate in flotation which can cause the content of MgO overhigh, therefore the molybdenum concentrate grade can not meet the industrial requirements. Thus the utilization level of talcose molybdenum resources has been restricted greatly.The adsorption of water on talc and molybdenite surfaces and natural floatability of minerals were studied by density functional theory method. The results showed that molybdenite and talc were layered minerals which exhibited similar surface wettability and H2O molecule prefers to stay with water rather than the minerals surfaces. N2 is adsorbed on talc and molybdenite surfaces more easily than H2O. The interaction and flotation behavior were studied by SEM and flotation experiments. The reason why talc interferes with the flotation molybdenite has been revealed. The agglomeration between molybenite and talc was caused easily in neutral or acidity solution, and it was dispersing between molybenite and talc particles in alkaline solution. The flotation results showed that good floatability of talc was the key factor causing a low grade of concentrate in alkaline solution. Thus, it is the key factor to enlarge floatability difference between molybdenite and talc.INTRODUCTIONMolybdenum is a kind of important rare metal and strategic reserve resources (Zhitao Y et al, 2016a). Due to excellent characteristic, such as high melting point, good thermal property and et al, it’s widely used in metallurgy, machinery, chemical, aerospace, and many other areas. It has become an indispensable metal in modern industry. Molybdenum generally exist in the form of molybdenite which is a kind of mineral with excellent natural floatability. Talc is a kind of typical hydrous and layered magnesium silicate minerals (Beattie D et al,2006a), which is one of the most common gangue mineral of the platinum group metal ores and metal sulfide ores (Tao L et al,2011). Due to its good native floatability, talc is easy entry into the concentrate product with foam in the process of sulfide ore flotation (Kelebek S and Smith S, 2006b), which resulted in decreasing concentrate indexes. Not on that, the high-content MgO of concentrate will also produce a series of adverse impact to the subsequent smelting (Lotter N O et al, 2008). Therefore, it is difficult to separate talc from sulfide ore concentrate effectively."

Jan 1, 2018

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 Z. C. Zhen

Basing on character of fine ores, and employing all the advantage of dissolved-air flotation, the study within the dissertation put forth the methods of superfine metal mineral flotation with dissolved-air flotation equipment, and constructed a full set of laboratory flotation system. Experiments both in water and in slurry were respectively carried out by means of this flotation equipment. Further study was also fulfilled on mechanism of air-dissolved released devices, and the key components of system including ejector, releaser and saturator were designed. Optimizing devices parameters were chosen by taking ideal performance of the devices into consideration, according to orthogonal experiments and tests on bubbles factors, those performance factors were called air release rate, air release efficiency. The results with some minerals are better than JJF flotation machine with 30 litres bulk. The Dissolved-air Flotation(DAF) machine shows great potentiality in treating super-fine metal mineral concentration. The research indicates the Dissolved-air Flotation(DAF) system has superiority over mechanical flotation machine in fine flotation. Air-dissolved released bubbles appear on the surface of hydrophobic minerals in priority, solving collision probability less in the tradition fine mineral separation, such that the metallurgy technology of fine metallic minerals are improved. The exploratory research is a foundation for industrial pilot, commercial test and equipment maturity in the future.

Jan 1, 2014

By C. Han

The analytical results of Dagushan grinding workshop primary grinding operation product show that the size fraction of -0.079mm is 32.88%, the size fraction of -0.01mm is 9.97%, the rate of -0.01mm size fraction and -0.079mm size fraction is 30.32%. It means that there is too much -0.01mm size fraction in primary grinding operation product and fall out that there will not be a better result in following operations. Several tests have been carried out to control the size distributing of the primary grinding operation product according to confirm the appropriate conditions of grinding operation. Integrate with theoretic count, grinding property tests show that the appropriate rev ratio of ball mill should be between 85% and 90% so as to get better size distributing. Based on the results of grinding property tests, the shocking property tests simulated the momentum of different diameter steel balls in the ball mill have been carried out. It showed that if want to get better size distributing the appropriate diameter of steel ball should be 110mm. The tests result shows that regulate diameter of steel ball and rev ratio of ball mill could control the size distributing. Contrast to the technical parameters of ball mill in grinding operation now, there are some significant advices are given for practice and industrial tests.

Jan 1, 2014

By A. P. Liu

Semi-industrial test on fine products of Meishan dressing plant was carried out with type RP80/25 high pressure roller mill produced by Homburg Corporation of Germany, and the influences of such factors as energy consumption, water containing, throughput and circulating load on rolling effect were investigated. Closed circuit experiment result showed that Meishan iron ore could be suitable for powder grinding with high pressure roller mill, and energy consumption of the operation was declined by 25%~30%, which was favorable for energy-saving, increasing production efficiency and improving grinding effects. According to above experimental results, this paper put forward the technical proposal of application of high pressure roller mill in Meishan, and pointed out some technical problems which needed to be settled urgently in technology disposal.

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 Xiaoxu Sun, Jianchao Yao, Jiancheng He, Shijie Lu, Hongxi Zhou

"With the trend of increasingly more mineral resources turning low-grade and refractory, more and more new ore bodies being developed worldwide are more finely grained, which drives the rapidly development and application of techniques related to tower mills (vertical spiral stirred mills). However, the lacking in fundamentals of fine grinding, as well as standard procedures for equipment selection and scale up, seriously restraint high efficient application of tower mills. Taking grinding media motion characteristic and grinding intensity as a breakthrough point, this paper studies mechanisms behind how critical parameters affect grinding efficiency of tower mill, including ratio of screw pitch and diameter, agitator rotation speed, grinding media size. Several sets of orthogonal test are conducted on the quartz ore using the grinding system of KLM-3 tower mill. All the tests are under the same character of feeding mineral and undergo the consistent sampling for at least 60min grinding time. The input power is measured by a torque measurement system and the grinding products are analyzed by the laser particle size analyzer. The test results show the influence of parameters on grinding efficiency. Among the three important parameters, the effect of grinding media diameter is the biggest, followed by the agitator tip speed, and finally the ratio of screw pitch and diameter. For the different particle size of grinding products, the best combination of grinding parameters is different, with the mineral size becoming finer, the ratio of screw pitch and diameter become smaller, the diameter of grinding media become smaller, while the agitator tip speed does not change too much. The conclusions of the study help us to improve the grinding efficiency of the tower mill, to assist in the selection and optimization of working parameters, establish new scale up method on the basis of grinding model and eventually provide theoretical basis of rational selections of structural and media physical parameters within tower mill."

Jan 1, 2018

By F. Burat

At the present time, methods of mining and coal preparation produce tones of coal fines. The removal of water from these fines is necessary for economical and technological reasons. Supplementary processes that utilize different physical and chemical methods have been developed to in-crease the productivity of mechanical dewatering processes. Researches have shown that chemical reagents used along with conventional systems diminish moisture and increase the capacity and the yields of the dewatering method. In this study, the parameters of the vibrating screen (incline, frequency, feeding rate and screen size), the effects of the application of additional vertical mechanical vibration and surface active reagents (CTAB, SDS, Umectante B-70 and Kerosene) were investigated. At the end of the optimization experiments, 61.0% moisture was decreased to 42.3%. By keeping optimum conditions con-stant, the experiments have been conducted to determine most effective reagent. 41.2% moisture has been obtained with 5 g/t CTAB at the normal pH of the pulp, which were 7.25. By using vibrating screen with combination of the vertical vibrating mechanism, CTAB gave the best result of 40.7% moisture. Finally, the effect of increased surface area of the screen has been investigated and de-creased the moisture level to 38.7%.

Jan 1, 2014

By D. W. Lui

Tangdan copper oxide deposit, the largest independent copper oxide deposit in China so far, is located in the northeast of Yunnan province, southwest of China. The ore from this deposit is characterized by: low grade, high oxidation ratio, and fine-grained disseminated, resulting in poor flotation recovery. The analysis of plant flotation data reveals that the loss of copper minerals into tailings is mainly with coarse size fraction due to insufficient liberation and fine size fractions, especially minus 10 microns fraction, which proved to be very difficult-to-float with conventional flotation. In order to improve the performances of plant flotation of this ore, laboratory flotation tests were conducted with the pure malachite, which was the principle copper oxide mineral in Tangdan copper ore deposit. The results obtained suggested that a finer grinding (up to -325 mesh or even -400 mesh) be needed to decrease the loss with coarse size fraction, and vacuum flotation is a promising way for the recovery of the fine malachite effectively.

Jan 1, 2014

By Y. Rama Murthy

Around 90% of the chromite resources of India are concentrated in the Boula-Nuasahi Sukinda belt of Orissa state. In order to conserve these valuable ore resources strategically, several companies established chrome ore beneficiation plants in this region. The general beneficiation process in these plants consists of gravity unit operations such as Floatex density separator, spiral, wet shaking table etc. Most of these gravity circuits suffer huge losses of valuable minerals in the tailing. Any attempt towards decreasing these losses would not only increase the limited reserves in India but also make the economics of the operations more attractive. Apart from the liberation phenomena, in many of the operating plants considerable quantity of values are lost in the tailings, due to inconsistent feed quality, inappropriate selection of operating and design parameters. Mineral engineers in this regard have to play a proactive and continuous role to improve the performance of all separating units by modifying even small changes based on tests conducted in laboratory under controlled conditions followed by attempts to make necessary changes in the plant. For such improvements, accurate data collection and proper data interpretation followed by making necessary change which is implementable in an operating plant play a very critical role in performance of the circuit. Databank collected over a period of time under various conditions would also help in overcoming the future problems related to either variation in the feed characteristics or specific demand by metallurgical industries. The above concept was adopted in one of the operating chromite beneficiation plant at Sukinda. The approach adopted and practical problems encountered during the study were reported in this paper. The result of trial campaign has shown that, an overall product assaying 30.2% Cr2O3 from the feed (18% Cr2O3 ) can be produced to in single stage. The final discards of the process contain 12% Cr2O3. Keywords: chromite, chromite beneficiation, chromite losses, gravity concentration techniques, plant operating data bank

Sep 1, 2012

By D. Moradkhani

The heap leaching of oxide copper ores with copper cathode recovery by solvent extraction and electrowinning is now well established as a low-cost method of copper recovery. The main purpose of this study was to extract copper from the copper low-grade oxide ore of Chodarchaei mine using column leaching. The copper oxide ore contained 1.1% Cu and 1.75% Fe. The mineralogical analysis indicated the malachite (Cu2(OH)2CO3) was mainly composed of oxidized phases. The sulfuric acid leaching experiments were performed under the laboratory conditions. The influence of several parameters on the course of the reaction such as particle size, acid concentration, flow rate, and time was examined. The optimum collective extraction of copper and iron was obtained at a particle size of +10-15 mm for a leaching duration of 3 days with sulfuric acid concentration of 100 gpl and using a flow rate of 2.5 cc/min. Under these conditions, the recovery of copper and iron were 98.54% and 41.99%, respectively. Keywords: column leaching, copper, iron, working diagram.

Sep 1, 2012

The characteristics of mineral resources and tailings resources in China are analyzed. Those tailings, which have double characteristics, can occupy land, pollute environment and even influence human habitat if they are not disposed in time. So pay attention to the comprehensive utilization of the tailing more and more both at home and abroad. The present situation and problems in comprehensive utilization of iron tailings in China are introduced by combine some practice experience, and have looked forward to the comprehensive utilization of iron tailing situation.

Jan 1, 2014