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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 S. Serranti

A fast, reliable, and low cost characterization of ore minerals products, as they result from different processing actions, represents one of the most challenging targets in the mineral processing sector. Today different techniques are available according to different sampling strategies and analytical principles. In this paper, the possibilities offered by the adoption of hyperspectral imaging based sensing units working both at micro- and macro-scale are presented and discussed. According to the different phases and stages of ore minerals and products characterization, and starting from the analyses of the detected hyperspectral firms, it is thus possible to derive useful information about mineral flow stream properties and their physical-chemical attributes. This last aspect can be utilized to define innovative process mineralogy strategies and to implement on-line procedures at processing level. The present study discusses the effects related to the adoption of different hardware configurations, the utilization of different logics to perform the analysis and the selection of different algorithms according to the different characterization, inspection, and quality control actions to apply. Keywords: process mineralogy, hyperspectral imaging, NIR spectroscopy, surface mapping, textural analysis, quality control

Sep 1, 2012

By Z. Naziemiec

Since several years in Poland a huge demands on mineral aggregates occur, for the reason of intensive development of housing and road industry, as well as industrial building. Limitations in re-sources of broken aggregates in Central and Northern parts of Poland cause, that both the non-waste production of aggregates with high quality and the production of alternative aggregates from recycling gain greater importance, nowadays. It entails increase in demands for crushing devices, which are easy and reliable in operating as well as inexpensive and enabling to obtain a good quality products. Jaw crusher, regarded as the most spread in Polish industry, meet these requirements, however, their crucial disadvantage is a large content of irregular grains in crushing products. Numerous investigations show, that the shape of grains is a significant feature of aggregates, which influences on durability and quality of produced concretes. The advantage of jaw crushers is their easy operation, low price as well as low amount of dusts (wastes) generated in comminution products in comparison to other types of crushers (i.e. hammer crushers).

Jan 1, 2014

By W. Y. Liu

A sulfate reducing bacteria strain (named SRB-A) is isolated from sanitary wastewater by using anaerobic technology of Hungate. The studies of physiological, biochemical and phylogenic of the isolated strain are carried out. The colonies of the strain are circle. Cells that are slightly curve, rod-shaped with the size of 1.0~3.0µm in length and 0.8~1.0µm in width. The optimum temperature for growth of the organism is 30~35°C. The optimum pH for growth is 7.0~7.2. Strain SRB-A can use sodium lactate, sodium citrate, sodium acetate, ethanol and acetone as electronic acceptor but can not use glycerol, glucose, sucrose and sodium oxatate. The isolated strain reduces sulfate, sulfide, sulfur, DSMO and FeCl3, then nitrate and nitrite can not be used. The strain has higher tolerance of NaCl, and the optimum growth occurs in the presence of 5%~8% (w/v) NaCl. The result of 16S rDNA sequence analysis indicates that the isolated strain SRB-A is the most similar to Desulfo-vibrio halophilus, and the level of the similarity was 98.4%. The isolated strain has a stronger ability to reduce sulfate, and the level of sulfate reduction reaches about 90% at pH 7 in the liquid medium. 0.6 to 0.8 is the optimum COD/SO42- in the medium for the isolated strain to show better ability to reduce sulfate. At pH 2.5 the level of removal of Cu2+ reaches 96.3%. Under the condition of pH 3.5, the level of removal of Zn2+ reaches 92.6%. When the value of pH reaches about 7, the Fe3+ is precipitated by the formation of Fe(OH)3, and Fe3+ is removed up to 89.4% at last.

Jan 1, 2014

By Q. Zhang

The flotation behavior of jamesonite was investigated with ethyl xanthate as a collector. It has been shown that jamesonite has good floatability from pH 2 to pH 12, and relatively poor floata-bility at pH>12. The flotation of jamesonite was also dependent on pulp potential at certain pH val-ues. The potential-pH range for jamesonite flotation was established. The FTIR spectroscopy analy-sis and XPS measurement showed that the major adsorption product of ethyl xanthate on jamesonite was lead ethyl xanthate and antimony ethyl xanthate. The intensity of the FTIR signals of metal ethyl xanthate adsorbed on jamesonite and the flotation response of jamesonite were correlated with pulp potentials.

Jan 1, 2014

By S. Jagdish

India ranks fourth in the world of iron ore production and exported 55% of the total iron ore production of 180.9 million tons in 2006-07. As per United Nations Framework Classification (UNFC), the total iron ore reserves in India is 25249 mt. This consists of about 14630 mt of Hematite ore and 10619 mt of Magnetite ore. While the deposits of magnetite iron ore are limited to the states of Karnataka, Andhra Pradesh and Tamil Nadu, hematite ore is available in abundance in Jharkhand, Orissa, Chhattisgarh, Karnataka and Goa. National Steel Policy, declared by government of India in 2005 envisages 110 million tons of steel production by 2020. This is likely to be revised upwards. Massive exploration work in iron ore is needed to convert the available resources of iron ore into reserve category. Steel Authority of India Limited (SAIL) produced more than 24.5 million tons of iron ore during 2006-07 and plans to produce 42.0 million tons per year by the year 2010-11 to meet the requirement for a hot metal production of 26.2 million tons. While processing iron ore, the challenge faced would be the reduction of the gangue materials ? alumina and silica. It is proposed to bring down alumina and silica in the iron ore to less than 2% each from the current level of 2.5%~3.5% each. Appropriate beneficiation schemes are being developed depending upon the mineralogical characteristics of iron ores at different mines in the country. The state-of-art beneficiation technologies like Hydro-cyclone, jigging, magnetic separation etc. will be incorporated. SAIL?s corporate plan envisages blast furnace burden of 15% iron ore lumps, 15% pellets and 70% sinter by 2010. This strategy opens up the opportunity of utilization of micro fines generated in the mining and beneficiation processes for pellet making. This also directs towards all together new technological approach to the beneficiation process. SAIL is planning to set-up three pelletisation plants of 2~3 mtpa capacity. Environmental issues like reduction in slime loss and utilization of dumped low-grade iron ore are very important. R&D Centre for Iron and Steel, SAIL has carried out extensive laboratory investigations in the above area. This will help in reducing the loss of valuable iron through slimes and also increase the iron ore resource base. Laboratory investigations indicate that low grade dumped ore fines with Fe: 55.5% can be upgraded to a product with Fe: 66.2% with about 48% recovery.

Jan 1, 2014

By A. Gueciouer, A. Akkouche, K. Chalah, A. Benmounah

"Drilling solid waste is a typical industrial solid waste, and it is a major pollutant source to ecological environment. Generally, waste management dewatering systems separate solids and fine particles from the liquid phase of drilling fluid, thereby leaving a clarified aqueous solution and allow the cleaning of waste fluids. Typically, dewatering waste management systems clean drilling fluid through coagulation, flocculation and/or mechanical separation. Chemicals used in dewatering are based on the coagulation-flocculation process, which it facilitate the removal of suspended solids and colloidal particles. The factors which can promote the coagulation-flocculation are velocity gradient, contact time, and PH. The objective of this work is to optimize a formulation adequate for dewatering based on the coagulation-flocculation process used coagulant (Aluminum sulphate), anionic flocculants (Partially Hydrolyzed Polyacrylamide) and anionic polyelectrolytes (in solid form with linear chain with very high molecular weight). The results obtained show the good efficiency of the coagulant and flocculants. INTRODUCTION Rig site dewatering of drilling fluids with recycling of processed water can help an operator to comply with environmental rules by reducing volumes of waste and reducing long term liabilities. It can also reduce disposal costs and provide a cleaner drill site overall. Most of the environmental concerns during the 1980s involved hazardous materials and toxic wastes. Drilling fluids, many of which are chemically benign, have escaped many of the difficult-to-comply-with rules and regulations. During the 1990s, however, operators may be required to submit a written plan for liquid waste reduction for even nonhazardous materials. Many states and local agencies may institute total bans on oil field wastes. Drilling rigs typically produce about 1 bbl of liquid waste for every 1 ft of hole drilled. Thus, a typical drilling operation can produce a large quantity of waste [1]. To improve the dewaterability of sludge, different pretreatment processes have been widely studied and developed including thermal, chemical, magnetic, mechanical, acoustic, electric, electro-acoustic and their hybrid treatment processes [2]. Rig site dewatering (figure 1) is the process of injecting coagulants or flocculating chemicals into the mud entering a large clarifying centrifuge. Coagulation occurs when the solid and allowing it to be attracted to other solids by van der waals forces. Flocculation is the binding of individual solid particles into aggregates of multiple particles. It is physical, rather than electrical, and occurs when one segment of a flocculating polymer chain absorbs simultaneously onto more than one particle [3]."

Jan 1, 2018

By Stoyan Gaydardzhiev, Michel Shengo, Pierre Kalenga

Lab-scale flotation of copper and cobalt oxidized ore from the Luiswishi deposit in the Katanga province (DRC) has been done focusing on the influence of the degree of process water recycling on metals recovery. Results have shown that at 20 % recycling rate, the recovery of copper and cobalt in the cleaner stage have been respectively reduced to 23 % and 45 % in comparison to 53 % Cu and 63 % Co if process water has not been recycled. At 10 % recycling rate however, the system could still tolerate the effect from recycling, since Cu and Co recovery has remained respectively at acceptable levels of 52 % and 60 %. In order to explain the reasons for the observed worsening of flotation results if process water was recycled at rate higher than 20 %, electrochemical investigation of the pulp has been performed. It has been established that the chemical compounds formed in the pulp when process water was recycled, do influence the sulphidization of malachite and heterogenite and impact further collector adsorption. To confirm these assumptions, the effect from thiosulphate ions presence during the sulphidization of high purity malachite has been studied. It has been found, that thiosulphate ions depending on their concentration in water induce variations in pulp properties such as DO content, pH, Es and contribute to formation of undesirable chemical compounds on mineral surface as identified by DRIFT spectroscopy.

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 Máximo Pérez, Julio C. Videla, Rosa Dzioba

"This paper reports the hydrometallurgical treatment of gravity concentrates of gold samples and outcrops associated with graphite ores obtained from:- flotation tailings of crystalline graphite minerals- outcrop samples of graphitic rock associated with auriferous minerals and free gold located in the Villa Union district and surrounding areas - La Rioja Province - Argentina.Previous studies of the flotation potential of crystalline graphite minerals failed to consider the presence of noble metals.The samples represent a mineralized zone of crystalline graphite which is distributed in different formations with a NE - SW trend in Maz, Punta Colorada and Las Ramaditas hills, covering an area of about 300 square kilometers.The most important variables affecting the leaching process, such as grain size, mineralogical species, reagent consumption, and so on, were previously studied. (Weiss, L.1985)On the basis of the present study results, the possible definition of an economically viable mineralization will be analyzed to define an auriferous district."

Jan 1, 2003

By A. Mainza, H. Hill, L. S. Bbosa

"Impact breakage is the most elementary size reduction mechanism in comminution devices. In comminution research, characterization of breakage is primarily concerned with the energy expended to cause it. The main challenges of this approach have been quantifying the actual energy requirements of impact breakage and developing mechanistic models to accurately describe the process. For engineering load analysis, fracture is characterized in terms of strengths such as yield stress and ultimate tensile stress, which govern the maximum loads specific materials can be subjected to before irreversible inelastic deformation and subsequently complete fracture occur. With this approach, the main challenge has been to elucidate the underlying mechanism, in the means that the load causes weaknesses in the material microstructure to act as sites for stress concentrations, leading to crack initiation, propagation and eventual failure. Studies dedicated to investigating particle fracture under impact loading have led to the development of several devices for conducting breakage characterization tests. These devices include the drop weight tester, split Hopkinson pressure bar, rotary breakage tester and the short impact load cell. All these have different particle loading and breakage methods, and thus can yield distinct information which can be compiled together to study a material and the nature of breakage. This work analyses the single impact breakage data obtained across the listed devices. A homogenous ore commonly known as blue stone is used for all breakage tests. The work is conducted using standard procedures specific to each device as closely as possible. Drop weight and rotary breakage tests were used to obtain hardness parameters based on an existing t10 breakage model, while split Hopkinson pressure bar and short impact load cell measurements provided properties based on conventional engineering load analysis. The results were used to highlight the significance of the loading geometry, impact mechanism and impulse on the extent of breakage."

Jan 1, 2018

By Kaioeng Wang, Qi Liu, Yahui Xiang

"In the differential metal sulfide ore flotation it is desirable to replace the toxic inorganic depressants with environmentally benign chemicals. Chitosan, as a natural and non-toxic polymer, has been proven to be an efficient depressant for chalcopyrite while allowing galena to be floated by xanthate collectors. However, the poor solubility of chitosan limits its potential applications as the flotation could only be carried out at about pH 4 where chitosan is soluble. A carboxymethyl derivative of chitosan, named N-carboxymethyl chitosan (N-CMC), was synthesized by substituting the amino groups of chitosan with carboxymethyl groups. The substitution significantly improved the solubility of chitosan. The structure of N-CMC was studied and compared with chitosan via Fourier transform infrared spectroscopy (FTIR). Flotation tests were performed on single minerals and mineral mixtures (with weight ratio of 1:1) with the addition of appropriate amount of potassium ethyl xanthate (KEX) and N-CMC. The solution pH was varied from neutral to alkaline. The flotation concentrates and tailings were collected and analysed for the contents of copper and lead. FTIR measurements showed that new peaks of C=O stretching of -COOH and N-H deformation of -NH- appeared in N-CMC, which indicated that the carboxymethyl groups were introduced and the amino groups were the sites for the substitution. Flotation results indicated that N-CMC could depress either chalcopyrite or galena depending on the pH. The results were not affected by the sequence of KEX and N-CMC addition. Therefore, N-CMC is potentially useful in Cu-Pb sulfide separation following a bulk Cu-Pb flotation. The N-CMC was also found to have surface cleaning functions, and was able to remove contaminating copper ions from galena surfaces. Therefore, its application in sulfide ore flotation is expected to be more robust than the original chitosan."

Jan 1, 2014

Beneficiation and dephosphorization of refractory oolitic hematite ore are investigated in this paper. It is shown that single magnetic separation, gravity separation or flotation is unable to recover iron effectively from the ore due to the complex mineralogy. The joint separation by spiral chute-shaking table shows a prospect for the treatment of the ore. An iron concentrate with 58.67% iron grade and 51.93% recovery is obtained by the joint separation of spiral chute and shaking table under the fineness of ?0.074mm 90% and dispersant dosage of 2kg/t for a sample ore of 37.51% Fe and 0.88% P. However, P content in the concentrate is still up to 0.52%. Dephosphorization from the concentrate is hence carried out. The final iron concentrate assaying 59.26% Fe and 0.056% P is obtained when the concentrate obtained by joint separation is leached by sulfuric acid of 1% (mass fraction) with solid percentage 10% at room temperature for 10min.

Jan 1, 2014

By A. N. Zagorodnyaya, T. N. Bukurov, Z. S. Abisheva, A. S. Sharipova

"The paper describes the results of stripping of copper production dusts by leaching with aqueous soda, nitric acid solutions and recovery from solutions resulting in the production of lead sulphate, tribasic lead sulfate (TBLS), ammonium perrhenate, zinc, copper-cadmium cake.The combination of two stripping operations under chosen optimal conditions allows the recovery of 98% rhenium, 82% lead, 92 % copper, and 96% zinc and cadmium each. The major amount of rhenium (~ 80%) is recovered at the carbonization stage, and other metals - at the nitric acid leaching stage.Lead sulfate was precipitated by mixing solutions resulting from carbonization and leaching. Tribasic lead sulfate was produced by dissolving lead sulfate in sodium hydroxide solutions. Rhenium was recovered from mother liquor resulting from lead sulfate precipitation by liquid-liquid extraction and zinc was recovered from raffinates. Trialkylamine (TAA) was used as an extractant for rhenium recovery and di-2- ethylhexylphosphoric acid was used for zinc recovery. Optimal liquid-liquid extraction parameters have been defined allowing the recovery of 96% rhenium in crude ammonium perrhenate and 94% zinc in sulfuric acid solution. Based on the experimental data, the flowchart for dust processing to produce salable products - lead, rhenium, zinc salts has been suggested."

Jan 1, 2003

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 D. Moradkhani

Copper metal has important role in the basic industrials, as if it did not exist, modern human life would not develop! Copper leaching, as the first step, is important step in copper production processes. In this research, efficient factors on the leaching have been investigated. For this reason, four efficient factors on leaching namely pH, liquid to solid ratio (L/S), temperature and time, as independent variables, were optimized using response surface (RSM) with D-optimal. A quadratic equation was used to create response and contours. According to the results from analysis of variance (ANOVA), the value of determination coefficient (R2=96.77%) indicates that the model was good fit. Optimum experiment condition also was found: pH of 1, L/S of 8.24, temperature of 26.06 ? and time of 43.64 min. At this condition, the maximum recovery of copper was equaled to 92/38 in which good desirability achieved.

Sep 1, 2012

By Priyanka Dhar, Kurt Aasly, Hanumantha Rao Kota, Hassan Bouzahzah, Maria Thornhill

The interest in investigating the processing characteristics of mineral deposits in Norway has seen an upsurge in the last decade. One of the major areas of interest is a huge copper deposit, operated by NUSSIR ASA located in the Repparfjord Tectonic Window in the caledonides of west Finnmark. This study reports analysis of ore from the deposit for development and modifications in the flotation flowsheet for the NUSSIR ASA copper ore. The mineralogical characterization for the ore sample was achived by optical microscopy and Zeiss automated mineralogy while grinding characteristics were tested using Bond Index tests. The results confirmed the presence of Cu minerals in the form of chalcocite, chalcopyrite and bornite in the samples, which are mainly liberated in the – 105 µm size range. The majority of non-liberated copper sulphides associated with silica and the carbonates varies from 3 to 28 percent in the –250 µm samples . It is also observed that the copper minerals are uniformly distributed in all size ranges. Selective flotation of NUSSIR copper ore was performed in different size fractions with a motive to identify the correct liberation size and thus to obtain a copper concentrate meeting the quality requirements. The flotation experiments are essentially performed in two stages: the rougher and the cleaner stage. Mass balance calculations were performed showing that approximately 88 percent of copper can be obtained at the end of the process. Ultimately, overall circuit copper recoveries ranged between 83.5 to 88.1 % with a concentrate grade of 35 to 48 % Cu.

Jan 1, 2018

By Anuj Narang

Large-scale separation or flotation cells, used in the primary extraction in the oil sands industry, are integral parts of the overall process of bitumen extraction. Good regulation of the interface level between the bitumen froth and the middlings in these cells can result in a significant improvement in bitumen recovery and throughput, and heavily influence process economics. Automatic control of such industrial processes presents challenges such as multi-phase flow dynamics, variable process gain and time delays, poor quality of measurements and significant disturbances. This paper details a case study application of development of multiple models of the dynamics of the interface level and the design of model predictive controllers (MPC) for a separation cell process. A Model predictive controller (MPC) using linear models is designed and implemented in real time on an industrial separation cell. The industrial implementation results show that the MPC scheme provides significant benefits over the current operations which use a PID controller. The benefits include significant reduction in the variance of the interface level resulting in higher bitumen recovery and smoother downstream operation plus energy savings due to reduced underflow pump speed.

Sep 1, 2012

By D. R. Nagaraj

The traditional (popular) approach to reagent development and optimization, which has become entrenched in both research and practice for many decades, is highly reductionistic, incremental and costly, does not produce robust chemical solutions, and is not sustainable. There are also several other key drivers and changes in the mineral industry that clearly warrant a new approach. In response to these, an intense effort was made at Cytec over the past fifteen years to develop a meaningful, efficient, and sustainable approach to develop new reagents and robust chemical solutions in mineral separations. This effort culminated in three important outcomes: a) development of the holistic approach, called FLOTATION MATRIX 100? process, b) novel reagents, and c) enhanced application knowledge for reagents. In this paper, the efficiency, utility and power of the holistic approach will be demonstrated with examples using both existing and new reagents in the processing of Cu-Au, Au and Cu-Mo ores.

Jan 1, 2014

By H. H. Li

Reverse flotation is usually used for hematite/silica or bauxite/clay flotation separation in which the silica or clay is floated and rejected. Some properties of these silicate minerals such as particle size and surface characteristics have significant effect on their flotation behaviours. Firstly, the silicate mineral particles (especially clay minerals) generally have fine particle size (< 5 microns) in their natural states or due to overgrinding and they display poor flotation kinetics, consequently having low flotation recovery. Secondly, the wettability difference on different particle basal planes influences the affinity for adsorptions of different types of chemicals such as collectors or macro-molecule. Common polyacrylamide (PAM) flocculants can be used to minimize the exposure of the most hydrophilic planes of clay particles via hydrogen bonding but they can not efficiently enhance the overall particle surface floatability due to the hydrophilic properties of this type of macromolecules. A novel method to improve both flotation kinetics and surface wettability of silicate minerals has been developed and studied. That is to use a temperature-sensitive polymer, poly (N-isopropyl acrylamide) (PNIPAM), as a process aid in the flotation of silicate minerals. Unlike PAM polymers, PNIPAM can induce a hydrophilic/hydrophobic transition on the particle surface when the temperature is changed to be lower or higher than its critical solution temperature (CST). At a lower temperature, the PNIPAM adsorbs on the particle surface via hydrogen bond similar to PAM. It induces strong hydrophobic aggregation when the temperature is increased above the CST. Thus, both floc size and mineral floatability are greatly increased. The flotation results show very good flotation performance and the addition of conventional flotation collector was no more required because the increased particle surface hydrophobicity induced by PNIPAM. Contact angle measurements explained the role of PNIPAM in manipulating particle surface hydrophilic/hydrophobic transition.

Jan 1, 2014