Search Documents

By N. P. Haran

A detailed study was undertaken to beneficiate sub-grade iron ore sample from Kenojhar District, Orissa, India containing 57% Fe (T), 7.7% SiO2, 4.8% Al2O3, 4 % L.O.I. 0.4% TiO2,1.3 % Mn and traces of S(T) to make it suitable for the user industry. The mineralogical study indicated that it predominantly consists of haematite with subordinate amounts of goethite and clay. Quartz, Cryptomelane / Psilomelane, Pyrolusite, Gibbsite, Feldspar and Muscovite mica were present in very minor to trace amounts. The Denver grind ability tests indicated, that the sample could be categorized as ?medium soft to medium.? The Bond ball mill work index was determined to be 14.19 kwh per short ton. The beneficiation process involved classification followed by tabling of the classified sand, ground to minus 48 mesh size. The table slimes were subjected to Wet High Intensity Magnetic Separator (WHIMS). The developed process yielded a composite concentrate from tabling and WHIMS operations assaying 65% Fe(T), 2% SiO2, 1.8% Al2O3, 2% Mn and 0.9% LOI with a recovery of 60.1% Fe (T), amounting to 52.5 wt.% yield. To meet the size specifications for pellet making, it was further ground. Dewatering studies were also carried out on the ground combined concentrate and rejects. The thickener area of ground combined concentrate using 0.02 kg/t of Sufloc A 1115 flocculant was 0.02 m2/tonne of dry solids per 24 h. And for the combined rejects using 0.12 kg/t of flocculant, it was 0.035 m2/tonne of dry solids per 24 h. The moisture content, in the pressure filtration cake, in the ground combined concentrate product was 10.0%, and productivity was 506.7 kg/m2h. Thus, by thickening and filtration of process products, 90% of water used in the process could be recovered. The study highlights the development of a simple and cost effective flowsheet with almost complete water recovery for a subgrade iron ore sample. Keywords: tabling, WHIMS, thickener, filtration

Sep 1, 2012

By Xiaojing Li, Yueyuan Zhou, Shengyao Ma

The paper presented the acnalysis of field intensity of rare-earth permanent magnet with high BH product and the research of magnet configuration with narrow pole pitch on open magnet surface, both using ANSYS. The possibility to separate micro-disseminated feebly magnetic minerals by improving the field intensity and the capture line distribution rate on open magnet surface were verified. The research on the method to pile up magnets to increase peak value of field intensity on the open magnet to 1.0T was done through correlation analysis between shape and dimensions of magnetic material and field intensity. And the research on technology method to improve capture line distribution rate in the separating field to 1.25×105/m2 was done through optimization design of magnet configuration of the open magnet with narrow pole pitch. Laboratory tests were performed with hematite sample from ore dressing plant such as Hainan mine, Qidong iron ore, etc. The separation results acquired were at the same level as using the electromagnetic separator, verifying the possibility to separate micro-disseminated feebly magnetic minerals with open magnet. The research suggested a new idea about the development of magnetic separator with high efficiency and low costs to separate feebly magnetic minerals and non-magnetic gangues.

Jan 1, 2014

By A. A. Rogozhin, E. G. Likhnikevich, S. I. Anufrieva, A. V. Kurkov

"Russia is among the nations holding the world's largest lithium ore reserves. Lithium is of key importance for the global economy. Therefore, it is important to review the current state of technology research aimed at finding the most effective solutions for the recovery of lithium from promising reserves in Russia. In Russia, a number of process solutions for the flotation of spodumene into salable concentrate (5% Li2O) have been implemented at the earlier existing complex low-grade ore concentration project. By applying these solutions, a sample of high-grade spodumene ore (4.7% Li2O) of the Greenbushes deposit was processed into a spodumene concentrate (7.5% Li2O) at a high recovery (~93%) of lithium. In Australia and Canada, new processes have been developed for the recovery of high-grade spodumene concentrates from high-grade ores using dense medium separation and flotation. For the recovery of mica lithium concentrates from low-grade ore, a flotation process was developed in Russia using the cationic collector ANP-2 and Oxifos-B as an additional collector. Low-grade ore containing 0.14% of lithium oxide was processed into a 2.7% Li2O concentrate. New hydrometallurgical lithium concentrate and ore processes are developed to avoid high-temperature (>1000 °C) roasting. The Sileach process (Australia) includes leaching of lithium ore with sulfuric acid in the presence of a halogen-containing component at a temperature of 95-115 °C. In the Russian process, lithium is recovered into an alkaline solution from low-grade spodumene ore in a pressure alkaline leaching environment (250 °C, NaOH concentration > 300 g/l). The developed concentration and hydrometallurgical methods will allow to design on their basis efficient processes for recovering salable products for hi-tech industries from lithium ores.INTRODUCTION Lithium has many unique and important properties. It is the least dense hard metal. Its alloys have some of the highest strength-to-weight ratios. Lithium has the lowest melting point of all known solid elements and is used as a highly-effective heat transfer medium. The high demand for lithium is due primarily to its unique electrochemical potential and low thermal expansion coefficient. It is used in the production of glass and ceramics, in petrochemicals, metals, medical and other industries. Since the late 20th century, the electronics industry has been the largest consumer of lithium. In recent years, lithium has attracted much attention also as an important component of ultra-lightweight electronic devices. It is also the preferred metal for electric batteries used in mobile electronic devices, vehicles, household power generators, making it an important resource for the development of environmentally friendly technology. Leading automotive brands have ambitious plans for the production of electric cars — Tesla Motors, VW, Toyota, GM, BYD Auto. It is expected that the production of electric vehicles alone will triple the demand for lithium by 2025. A sharp increase in the production of lithium is expected. Lithium has all the prerequisites to become a strategic resource of the 21st century. (Deutsche Bank, 2016; Bradley et al, 2017)"

Jan 1, 2018

By J. Masinja

The mining industry is known to be a potential major contributor to the industrial development of any economy. Large-scale mining has been going on in Zambia for the last 100 years. The impact of mining in Zambia has been to create a development corridor along the line of rail to the Copperbelt Province, where hitherto, mining was concentrated, and then to develop a large consolidated high-density economic zone covering an area of about 72 km by 60km. This area is home to a number of very large integrated copper/cobalt mining complexes. The mining zone has expanded to the Northwestern Province in the last 10 years, where the largest copper mine in Africa now exists, having produced about 300 000 tonnes of copper in 2011. The total output of the Zambian mining industry is now about 820 000 tonnes per annum with projections of reaching 1.5 million by 2015, due to new Greenfield investments expected to come online by then. These new mining industry developments have come on the back of strong and sustained high base metal prices, in the last 10 years or so, due to demand mainly from China and India. This new lease of life has increased the contribution of the sector to the national treasury. The mining industry in Zambia has undergone a very important ownership restructuring with the sale of the previously Government owned parastatal, Zambia Consolidated Copper Mines (ZCCM) which dominated the sector, to allow for private sector participation. The privatization process lasted from about 1995 to about 2002. The recent growth of the mining sector has unfortunately not been matched by an adequate supply of skilled manpower for various reasons. These include: (i) A lack of strong in-house training strategies by the new mine owners (ii) Decrease in industry support to the training institutions (iii) The demise of and restructuring of ZCCM which has consequently limited the Government human resources planning tools for the mining sector (iv) The cyclic nature for the fortunes of the sector has lead to fluctuating interest of student recruitment into training institutions (v) Limitations, both staff and equipment, in the training institutions (vi) A re-structuring of the training institutions This paper examines the current status, and student output from tertiary training institutions for the mining sector in Zambia. This is then compared to the skilled labour demands of the sector. The various cause and effect issues are considered and a proposal on how this skills gap could be addressed sustainably is proposed. Keywords: skills gap, graduate training, quality of graduates

Sep 1, 2012

By X. Xu

This paper presents the research on comprehensive recovery of copper, gold, silver and iron from tailings from high-intensity magnetic separation in Tonglushan Mine. By comparison of experimental results of three flowsheets?regrinding of tailings-conventional sulphidizing flotation, water heating enhanced sulphidizing flotation and acid leaching-sulphidizing precipitation flotation, it is concluded that regrinding of tailings-conventional sulphidizing flotation flowsheet has the best economical and technical performance and practicability. Regrinding and using the mixture of sodium hydroxamate and sodium xanthate are two of the notable technical characteristics of this best flowsheet. The system for comprehensive recovery of tailings has been put into production. It not only can recover the valuable minerals from tailings in Tonglushan Mine, but also can reduce the environmental pollution, resulting great economic and social benefit.

Jan 1, 2014

By Arun Appadurai

Pneumatic transport systems play a vital role in conveying discrete particles over a sizable distance with minimal energy consumption. However if such a system is not designed keeping particle physics in mind, it leads to intractable problems which could possibly assume dangerous proportions, including but not limited to expensive redesign of the entire system. This paper describes a novel method, which harnesses the powerful technique of Computational Fluid Dynamics (CFD) to investigate a problem occurring in rotary kilns using coal as a major fuel source. In some of the sites, a unique phenomenon of abnormally high CO emission was observed and owing to the highly random nature of occurrence, it was difficult to scientifically investigate the problem and its cause. Most of the published solutions for the high CO problem tend to concentrate on the incomplete combustion aspect of the kiln and resolve the situation by increasing the air supply thereby improving the stoichiometric ratio of combustion. This paper offers an alternate correlation that relates high CO emissions to the phenomenon of coal delivery fluctuations caused by the sub-standard operation of the coal transport system. A CFD model for the coal delivery pipe is validated by utilizing the actual process data sourced from the measurements taken from a functioning plant. The results of the model are used to derive correlative conditions that point to the unstable operating conditions of the coal delivery pipe prevalent in the industry. The conclusions are summarized into a series of recommendations for optimized design of coal delivery systems which are implemented in a pilot plant. The results irrevocably prove a statistically significant reduction in CO emissions without resorting to increased air supply and power consumption. Keywords:CFD, Pneumatic Conveying, Saltation Velocity, Particle Flow

Sep 1, 2012

By Peng Qian, Xiao Li, Guoyan Fu, Peiwei Han, Yongliang Wang, Shufeng Ye

"Arsenic removal from high arsenic gold concentrate is conducive to increase the mineral value and realize the mineral comprehensive utilization. This study investigated the alkaline pressure oxidation leaching (APOL) of an arsenical gold concentrate in lower temperature to separate the arsenic into filtrate. The effects of temperature, NaOH concentration, solid-liquid ratio, reaction pressure and stirring speed on the leaching efficiency were investigated, and the characteristics of the gold concentrate and leaching residues were evaluated using XRD and SEM analysis methods. The obtained results showed that by using lower temperature (<60?) it is possible to avoid the production of elemental sulfur during the leaching process, which is benefit for the oxidation of arsenopyrite; When the reaction was carried out under appropriate conditions, more than 98% of the arsenic will be extracted into the filtrate as the form of arsenate or thioarsenate. INTRODUCTION In recent years, there has been considerable interest in the recovery of gold from refractory arsenical gold ore. The arsenic in this kind of ore usually exists as the form of arsenopyrite, and the gold surrounded by arsenopyrite exists as the form of fine particles, which will give many difficulties to metallurgical work. When the content of arsenic in the gold ore is more than 0.5%, it will seriously penalize the smelting efficiency (Ruiz et al., 2014). So pretreatment of the refractory gold ore is necessary to obtain the largest economic value and environmental benefits (Balaz et al., 2000). The oxidation pretreatment processes mainly include roasting oxidation, pressure oxidation, chemical treatment and biological treatment (Ann et al., 1992; Kou and Chen, 2012; Tongamp et al., 2010; Fernandez et al., 1995; Lin and Zheng, 1996). Among them, the roasting oxidation and pressure oxidation are the more ordinary processes in industry. The roasting oxidation process is the mature and adaptable technology, but the production of waste gas containing sulfur and arsenic will pollute the environment. The pressure oxidation method possesses certain metallurgical and environmental advantages, and can efficiently decompose the mineral. According to the different solution media, the pretreatment can be divided into alkaline and acidic pressure leaching pretreatments (Papangelakis and Demopoulos, 1990; Hiskey and Sanchez, 1995). The acidic pressure oxidation method has been used in most smelting plants for high arsenic gold ore pretreatment, while the alkaline pressure oxidation is still not widely applied. Compared with the acidic pressure oxidation, the alkaline pressure oxidation can be realized under lower temperatures."

Jan 1, 2018

By W. Q. Zhao

In order to raise the utilization rate of phosphate resource of Al-Jalamid Mine in Saudi Arabia, a flotation experiment for its phosphate rock was carried out by using WF-01collector that have been produced by Wengfu Phosphate Mine. The results showed that WF-01 collector had extensive adaptability for Al-Jalamid phosphate rock, and the grade of phosphate concentrate could be up to 33% P2O5 mixing the upper, middle and lower beds rock as well as its 80% more recovery.

Jan 1, 2014

By T. Wajima

"A novel carbonaceous immobilizing agent for heavy metal contaminated soil was prepared from rice straw using sulfur immersion and pyrolysis, and the lead immobilization in artificial contaminated soils using sulfur-impregnated carbonaceous material was estimated. The rice straws were cut to 1 cm pieces, and then immersed in 0.1 - 1 M K2S solution for 0 - 24 h to prepare sulfur-immersed materials. The immersed-materials were heated at 400 oC for 1 h in nitrogen gas to produce the sulfur-impregnated carbonaceous material by pyrolysis. The abilities of the product to immobilize lead from aqueous solution were examined to obtain the product with high lead immobilization ability. With increasing K2S concentration, the immobilization ability of the product for lead gradually increases and then above 0.5 M K2S those are almost constant, while 15 min is sufficient for the immersed time to obtain the product with high lead immobilization ability. The product prepared from material immersed in more than 0.5 M K2S solution for less than 15 min has a maximum immobilization ability for lead ion. The lead immobilization using the sulfur-impregnated product is sustainable due to the formation of leadhillite [Pb4SO4(CO3)2(OH)2] and anglesite [PbSO4]. The product can immobilize lead ion in various artificial lead contaminated soils. By mixing artificial lead contaminated soil with the sulfur-impregnated product, the eluted solution became neutral, and the eluted concentrations of lead ion dropped below the Japanese elution standard for soil.INTRODUCTION Soil contamination with heavy metals is a worldwide problem. Accumulation of heavy metals in soils affect soil ecology, agricultural productivity, quality of agricultural products, water resources, and serious health problems for human and animal (Raicevic, et al., 2005). In the United States, for example, approximately 63 % of the sites on the National Priority List (NPL) for the treatment of contaminated soils are contaminated by metals, and lead is the most common metal, found at 15 % of the sites. In Japan, according to a report by the Ministry of Environment, 43 % of the contaminated sites that exceed the environmental quality standards are contaminated by lead compounds. Soil contamination by lead compounds is also prevalent in other developed and developing countries where lead compounds are used extensively in industrial activities without careful contamination management. Lead is a ubiquitous heavy metal pollutant in soils due to their use widely. The primary sources of Pb contamination include industrial activities such as mining, smelting of metals, and the use of Pb-containing products such as paints, lead-acid batteries, bullets, gasoline and pesticides (Cao, et al., 2009). It can damage human nervous (especially children) and reproductive systems (ATSDR, 2007). The high concentration of Pb in the soil poses risks to human and animal health by the leaching of metals from the soil into water and the consumption of edible plants growth in the contaminated soil. Therefore, proper remediation is necessary to reduce metal availability in soil for protecting human health."

Jan 1, 2018

By Z. M. Wang

A large scale a polymetallic mine in north China is a refractory ore containing many useful com-ponents: W, Mo, Cu and Fe. Mineralogical investigation shows that the deposit is a quite complex one due to fine disseminated size and unevenly distribution of valuable, intergroth of sulphide and tungsten minerals, concurrence of scheelite and calcium minerals. Based on ore characteristic, a flowsheet is used by the floatation processing of sulfide minerals superior to scheelite. Bulk sulphide flotation is used in sulphides. Mo and Cu are floated in sequence after sulphides regrinded. Tungsten mineral is floated using combined depressant that is an effective depressant to gangue, and can improve the grade of rough tungsten concentrate. Compound depressant has high effective in removal of collector in gangue and sulphide, and tungsten is activated also. High quality of tungsten concentrate is obtained at satisfactory recovery. The test production obtains Mo concentrate with grade of 48.16%, recovery of 81.43%; W concentrate with grade of 66.47%, recovery of 78.19%; Cu concentrate with grade of 23.14%, recovery of 56.6%; Fe concentrate with grade of 67.33%. The valuable metals are recovered comprehensively and well techno-economic index is obtained. The mine enterprise profit is increased greatly.

Jan 1, 2014

By Janusz S. Laskowski

The flotation-related properties of hexanol derivatives and mono-alkyl ethers of propylene oxide, which include many important flotation frothers (e.g. MIBC, DF-200, DF-250, DF-1012, etc.) have been studied. The obtained results show that the DFI (Dynamic Foamability Index) - CCC (Critical Coalescence Concentration) plot can be used to classify flotation frothers. The frothers characterized by low CCC and high DFI values have properties of strong flotation frothers, while those with high CCC and low DFI values are more selective. The proposed frother classification system, based on simple CCC and DFI measurements, provides, for the first time, a solid ground-work for characterization of the flotation frothers.

Jan 1, 2003

By Kari Niiranen

LKAB (Luossavaara-Kiirunavaara AB) is operating iron ore mines, concentration plants and pelletizing plants in Northern Sweden. The largest of the apatite magnetite deposits and the mines are Kiirunavaara with annual production rate of approximately 27 Mt crude ore underground. LKAB produces two varieties of pellets: blast furnace pellets and direct reduction pellets (LKAB DR Oxide Pellets). Meanwhile the concentration process in a sequence of the low intensity magnetic separation (LIMS) and flotation at the concentration plant. In spring 2007 there were noticed great fluctuations of SiO2 grade in the crude ore. The high SiO2 grade is particularly problematic in the case of direct reduction pellets. In consequence, a project was started (called Silica in the Mine) to define exactly the problem related with silica and to find out, if possible, the reason for the great fluctuation of SiO2 grade in the crude ore going to the processing plant. A further target of this project was to develop a simplified method at the laboratory scale, to predict SiO2 grade in the magnetite concentrate in the future, but also predict the physical properties of the ore with respect to mineral processing. The essential stage of systematic characterization of the ore body for mineral processing properties is the estimation and simulation of different parameters from the laboratory scale to the large scale at the concentration plants using empirical data collected at the mineral processing by LKAB in Kiruna. Further a target was also to find useful physical parameters for mineral processing and implant those parameters into the existing geological 3D-model of the deposit. This information will be used for making prognosis of the future mining and the quality of the crude ore. It will also give better control and improve the production planning in the mine and the performance at the concentration plant in Kiruna concerning the decrease of the SiO2 grade of the magnetite concentrate.

Sep 1, 2012

By Sun Chuanyao, Cao Fei, Sun Desi, Zhou Dezhi

"The research applies the density functional theory and molecule design technology to design and synthesize the novel flotation collectors for copper-sulphur separation. Density functional theory (DFT) was applied to investigate the electronic properties of O-isopropyl-N-benzyl thionocarbamate (IP-BIAN) and O-isopropyl-N-ethyl thionocarbamate (Z-200). The calculation results show that both the energy of highest occupied molecular orbital (EHOMO) and the lowest unoccupied molecular orbital (ELUMO) of IP-BIAN are smaller than that of Z-200, electronegativity of IP-BIAN is higher than that of Z-200. According to the Klopman’s generalized perturbation theory, the collecting power of the two compounds is predicted to be Z-200 > IP-BIAN, the selectivity of IP-BIAN is better than that of Z-200. Then the thionocarbamate molecular is synthesized, and the compounds are characterized by nuclear magnetic resonance (NMR). It turns out that the test result identifies the prediction after the flotation verified test of pure mineral and actual mineral. The results demonstrate that the EHOMO and ELUMO are smaller in the thionocarbamate after a nitrogen atom is bound to benzyl, the thionocarbamate has strong selectivity and low collecting power. The lower the LUMO energy of thionocarbamate is, the stronger the back donation covalent p-bond between collectors and chalcopyrite is, thus improving flotation power for chalcopyrite and selectivity against pyrite. The result proves the feasibility of design and synthesis of the novel thionocarbamate through the frontier orbital properties of the collectors.1. INTRODUCTION Thiocarbamate is a kind of nonionic polar collector and is now widely used as flotation collector for copper-sulphur separation. The flotation power of thiocarbamate to chalcopyrite is stronger than pyrite, so it has high selectivity against pyrite. The frontier orbital theory and density functional theory (DFT) has been widely applied to study the structure-activity relationship of flotation collectors [1-6]. The flotation test results can be interpreted by using the reaction energy criteria and quantum-chemical parameters, such as the energy of the highest occupied molecular orbital (EHOMO) and the energy of the lowest unoccupied molecular orbital (ELUMO) of collector [7-11]. In turn, there are rarely reports about screening the novel flotation collector, by the frontier orbital properties such as HOMO and LUMO of flotation collectors. In this thesis, we apply the density functional theory and molecule design technology to design and synthesize the novel flotation collectors for copper-sulphur separation. Based on the previous findings of the structure-activity relationship of xanthogen formats [12], it has stronger collecting ability to chalcopyrite while the xanthogen formats after a nitrogen atom is bound to benzyl. Thus, in this study, a novel thionocarbamate molecule O-isopropyl-N-benzyl thionocarbamate (IP-BIAN) will be constructed, when the group structure connected with N atom in the known collector O-isopropyl-N-ethyl thionocarbamate (Z-200) is replaced with ethyl by propyl. The collectors (IP-BIAN and Z-200) have been calculated by DFT methods in quantum chemistry. By analyzing the reaction energy criteria and the frontier orbital properties (HOMO and LUMO), this research predicts flotation performance of novel collectors (IP-BIAN), then the synthetic experiments and flotation verified tests are conducted. The research provides a new theory reference for screening out the high-effective flotation collectors of copper-sulphur separation. This technology adoption will contribute to the sustainable development of mineral resources as it shortens the research cycle of new collector molecules and reduces the investment."

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 L. C. Zhou

The floatability of andalusite and associated minerals are studied and their action mechanisms of andalusite and associated minerals with collector alkyl benzene sulphonate are also studied. Through the mensuration of electrical potential and the infrared spectroscopy, as well as desorption tests, it is confirmed that the interaction of andalusite with sodium dodecyl benzene sulphonate (SDBS), is in addition to physical adsorption, but also is chemical adsorption. The study results of the pure minerals are used for the flotation of actual andalusite mineral. By flotation from contain-ing 45.68% andalusite ore, the fine andalusite concentrate is gained which Andalusite grade is 85.88%, containing Al2O355.29% and Fe2O3 less than 1.5%.

Jan 1, 2014

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 W. M. Zeng

A mixed culture of moderately thermophilic microorganisms was enriched from Acid Mine Drainage (AMD) samples collected from several chalcopyrite mines in China,which can leach copper from chalcopyrite effectively. Its tolerance to chalcopyrite was brought up to 80 g/L after being adapted to gradually increased concentrations of chalcopyrite. The effects of several leaching variables on copper recovery in Stirred Tank Reactor had been investigated. The ore contained chalcopyrite (62.2%) and galena (25.6%) as the main sulfide minerals. The results of the tests show that it is possible, operating at 8% of pulp density to attain copper extraction of 75% in 44 days. The leaching rate of chalcopyrite tends to increase with the dissolution of total iron. Microscopic counts of microorganisms in the solution tend to be higher at low pH range. Furthermore, the analyses of leached residues indicate that the passivation of this chalcopyrite is mainly due to the formation of a mass of jarosite and anglesite (about 48.3% and 21.7% in residue respectively), other than elemental sulphur layer. The bacterial community composition was analyzed by using amplified ribosomal DNA restriction analysis (ARDRA). Two moderately thermophilic bacteria species were identified as Leptospi-rillum ferriphilum and Acidithiobacillus caldus, with different proportion in the bio-pulp, 67% and 33%, respectively.

Jan 1, 2014

By E. Hulthén

Cone crushers are used in the mineral, mining, and aggregate industry for fragmentation of rock materials. Control systems for cone crusher settings are widely used to compensate for wear and to protect the machines. The eccentric speed in a cone crusher affects the number of compressions the material is exposed to and thus the particle size distribution of the product. Eccentric speed also affects crusher capacity. However, the speed of the crusher is mostly fixed, because speed changes must be made by shifting pulleys, a process which is quite time-consuming. By applying a frequency converter, which has decreased in cost during recent years, it has become possible to adjust the speed continuously. By also applying mass-flow sensors to the process, the crusher can be run optimally to yield the most sellable products in a given moment. Existing systems normally only protect the machine. The sensors can be mass-flow meters, e.g., conveyor-belt scales. To analyze data from the process and calculate the appropriate value for the speed, an algorithm has been developed. The developed algorithm was tested and evolved at a crushing plant for aggregates that produces around 350 kton a year. The algorithm was implemented in a computer that could communicate with the frequency controller, retrieve data from four mass-flow meters, and also interact with the opera-tor. The computer was reachable over the Internet for the researchers at Chalmers and the algorithm was tuned and improved on-line. The result is a crushing stage that consistently and maximally produces the most desirable product. The performance (yield of required products) increased by 4%. As a bonus, the lifetime of the mantles increased 27% on the evaluated crusher.

Jan 1, 2014

By Rong Fan, Roger Smart, Ning Xu

As part of an Australian Research Council project with Newmont and Newcrest mining companies studying the influence of clay minerals on rheology, hydrodynamics and flotation response, the cryo-SEM technique has been used to capture and image the clay (low crystallinity kaolinite Q38) aggregate structures in the flotation pulp immediately after collector and before frother addition. Samples were also collected from the earliest froth phase and the froth overflow corresponding to early and later concentrates. In this technique, a copper tube is filled with the sample during operation of the cell. The tube is immediately plunged into liquid nitrogen vitrifying the water phase before it can crystallise as ice thereby retaining the structures without volume or other physical change. After sublimation of the vitrified water surface, the aggregate structures are revealed and can be compared between pulp and froth phases from clays in different feeds and flotation conditions. The images from both low-clay ore and ore with clay content reveal various levels of aggregation as predominantly edge-edge connected aggregates similar to those found in our previous studies of high-clay tailings. For the samples from the ore with clay content, more extensive edge-edge clay strings are found in the early froth phase as compared to exiting froth overflow and the pulp phase with short edge-edge connected strings. It is suggested that the strings of clay particles result from edge-edge aggregation in the Plateau borders of the bubbles before breakage during sampling and the more extensive edge-edge aggregation in early froth phase is induced by crowding in the bubble borders. The clay strings collected into the overflow concentrate are almost all broken up compared with the Froth before drop-back. The implications for entrainment and entrapment mechanisms of gangue capture in froth will be discussed.

Jan 1, 2014

By Alban Lynch, Benigno Aquino, Hakan Dündar, Alexander Kalugin, Marco Delgado, Alberto Palomino, Ali Türkistanli

Dynamic separators are efficient dry classifiers because new designs during the last 50 years have reduced the by-pass and improved the partition curve. By contrast cyclones have been used as classifiers in wet grinding circuits for 50 years but without serious change and the early problems which were caused by high and variable by-pass, and different mineral specific gravities, still exist. High frequency screens are now used for wet separation and the operating characteristics of closed grinding circuits using cyclones or screens are discussed. Data come from circuits at the Condestable, Cerro Lindo, El Brocal and Catalina Huanca mines in Peru, the Eczacibasi mine in Turkey, and the Apatit mine in central Kola Peninsula in Russia. All classifier data are described by their partition curves and all mill data by their breakage rates. With cyclones the by-pass, d50, and sharpness of the partition curve change as operating conditions change but with high frequency screens the values vary little because the by-pass is low, the sharpness is high, and d50 depends on the aperture size. Data from all plants indicate that lower by-pass and sharper separation improve breakage rates and throughputs. An initial model of the screen is proposed.

Jan 1, 2014