Search Documents

By D. J. Hallbom

The ?yield plastic? rheological model describes the flow behaviour of a variety of non-settling suspensions, including many types of mineral slurry. The current paper presents the laminar flow relationship (pressure gradient vs. flow rate) for a yield plastic fluid flowing through a pipe or cylinder. Simplified algebraic equations, suitable for engineering purposes, are presented for yield plastic fluids with values of the scaling factor in the range that includes most industrially important slurries. The laminar pipe flow relationship is one of the most important fluids engineering calculations. It may be used to determine the rheological parameters of a material in a capillary rheometer or flow loop. If the rheology is known, these relationships may be used to determine the laminar flow pressure gradient in pipelines of various sizes.

Jan 1, 2014

By S. Mohanta

In composite washeries optimization of operating parameters to achieve maximum clean coal yield at the desired clean coal ash level is a major problem. This problem is more acute in countries like India, which have predominant reserves of difficult-to-wash coals. The constrained operational parameters of washing for some equipments make it more severe. In addition to this, the dependence of separating performance of different equipments upon various variables aggravates the situation. Here an attempt is made to find a numerical solution to get maximum yield and minimize the difference between the actual and the theoretical yield. The solution is arrived through constrained non-linear optimization of a multivariable objective function that utilizes spreadsheet tools; the method accommodates any number of source coals or washing size fractions. By using a designed Ep value the predicted yield of composite clean coal has been calculated and the yield is optimized subject to constraints on both the ash and specific gravity. It is shown that operational constraints of different washeries in the composite plant that utilizes gravity separation methods can also be over-come. The technique offers the coal preparation engineer an effective and straightforward method for determining the optimum cut-points of separation for different coals or blended coals to obtain maximum product yield at a specified level of ash content.

Jan 1, 2014

By Chuansheng Luo

If lead-zinc ores have high oxidation rate, separation of lead and zinc is very difficult. This paper studied the technology of preferential flotation by the coarse grinding and re-grinding. The lead concentrate grade is 51.40% and the lead recovery is 62.83% when feed grades Pb 1.74% and Zn 6.46% with oxidation rate being 13.75%. At same time, the zinc concentrate grade is 50.07% and its recovery is 90.01%.

Sep 1, 2012

By Mohammad Kor, David Beattie, Agnieszka Mierczynksa-Vasilev

The selectivity of polymer adsorption in mixed mineral systems is the basis for polymer depression of gangue minerals in flotation. Effective polymer depressants not only reduce gangue mineral recovery, they also have minimal effect on the recovery of the value phase, presumably through targeted adsorption on the gangue phase, and minimal uptake on the value phase. Traditionally, polymer depressant design has been guided by single mineral phase adsorption tests, with affinity and maximum adsorbed amount determined for gangue and value phases separately. However, there is a need to determine the actual extent of adsorption on the gangue phase while in the presence of the value phase. In this work, we report on the development of in situ atomic force microscopy (AFM) imaging for determination of polymer depressant coverage and morphology on mixed mineral surfaces. Our group has previously used AFM imaging on single minerals to connect adsorbed layer characteristics with bubble-particle attachment and flotation outcomes. Two sample types were used to test the methodology: (i) a mixture of two crushed/ground minerals encased in resin; and (ii) a composite mineral sample containing macroscopic regions of three different mineral phases. The samples have been used to probe the selective uptake of two modified dextrin polymers (octenyl succinate anhydride dextrin). AFM images acquired in situ (while all surfaces are immersed in the same polymer solution) of each mineral phase have revealed the natural selectivity of the polymer for the mineral surfaces. In all cases, the polymers adsorb on the all mineral surfaces present, but to a varying extent.

Jan 1, 2014

By Y. M. Fu

In order to evaluate the flotation process, the process flow sheet was investigated. The process mineralogy of main products was studied. Through chemical mineralogical and screening analysis as well as surveying using a microscope and scanning electro-microscope, the oxidation degree and mineral composition of main-products the liberation of main minerals, the occurrence of elements such as Pb, Zn were revealed. It is pointed that to determine the flotation process, the type of prod-ucts optimum grind of original ore and middling was provided on the basis of liberation of main minerals is reliable. As correct finer ground original ore, first high-grade lead-concentrates and zinc-concentrates fast was floated from a great part of free of the galena and sphalerite of liberated. Then for finely re-ground middling of locked mineral grains of difficult liberation, mixing lead-zinc-concentrates second was floated. The four products was best in contact with characteristic of ore of Fan Kou. Therefore be obtained certain to successful economic effect.

Jan 1, 2014

By Bharat Garg

The coking coal or clean coal from raw material division, Tata Steel Ltd. is a prime source of energy for inhouse steel making. Coal reserves of semi soft coking coal at West Bokaro is beneficiated by dense media cyclone and froth flotation processes to produce clean coal. In dense media cyclone process two byproducts-middling and rejects are also produced along with clean coal. With the growing demand for clean coal, it becomes imperative to maximize the recovery of clean coal in beneficiation processes. This will help, not only in reduction in cost of production, but also in raw resource conservation, and proper utilization. In this context, a case study was conducted at West Bokaro to identify opportunities for clean coal recovery from by-products. This paper mainly discusses the process for recovery of clean coal from byproducts and study of further liberation of clean coal from byproducts for economic consideration.

Sep 1, 2012

By N. J. Bolin

The Aitik copper mine is located in the north of Sweden and the concentrator at the mine started its operation in 1968 with a capacity of 2 Mton ore per year. Since then the operation has expanded several times, and today the capacity is 18 Mton ore per year. A new expansion plan was investigated in 2005, however the building of a new concentrator was found to be a better solution, giving a lower cost, a longer lifetime and more concentrates to the smelter at the coast. Several choices have been evaluated regarding the location of the concentrator?s crushing, grinding, dewatering, process control and water systems. The energy cost comparison has been an important factor when evaluating the various choices. The single most important decision has been in choosing the grinding system. Once again the fully autogenous grinding system, favoured by Boliden, has proven to be the best solution. The location of the mill, high and near the tailing pond, gives lower transportation costs for the ore and tailings, compared to other locations. A new water system will lower the pumping cost, give better control of water circulation to the plant and create fewer problems with permafrost in the tailings disposal area. Molybdenum recovery will be installed in the new plant using a separate circuit. A gold leaching plant was also investigated. Gold leaching is planned for the pyrite concentrate from the chalcopyrite/pyrite separation and the concentrate from the desulphurisation circuit that will be installed on the bulk flotation tailings.

Jan 1, 2014

By Xiao Ni

Alkyl hydroxamic acid was shown to be a suitable collector for the flotation of pyrochlore from carbonatite niobium oxide ores. In the direct batch rougher flotation from the ore without desliming, over 85% of the pyrochlore can be recovered at about 30% mass pull. Cleaner flotation tests showed that the rougher concentrate can be upgraded. The adsorption mechanisms of octyl hydroxamic acid (OHA) were studied by using high purity pyrochlore and calcite mineral samples and employing analytical measurements such as Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and UV/VIS spectroscopy. FTIR showed a shift of the vibrational frequencies of the carbonyl group in hydroxamic acid after adsorption on pyrochlore and calcite, and the shift was more pronounced on pyrochlore. XPS results indicated a lowering of the binding energies (chemical shift) of Nb3d5/2 and Ca2p3/2 electrons on pyrochlore, and the lowering of the binding energies of Ca2p3/2 electrons on calcite, again with the shift being more pronounced on pyrochlore. The results indicated hydroxamic acid formed stronger complexes with pyrochlore than with calcite. Adsorption isotherms indicated that OHA adsorbed more on pyrochlore than on calcite at low concentration. At high concentrations, the adsorption densities on both minerals were similar. All results explained the observed selectivity of the reagents in the flotation of the carbonatite niobium oxide ores.

Sep 1, 2012

By Willis Forsling, Prabhakar Swarna, Hanumantha Rao Kota

The solubility of wollastonite and its Hallimond flotation behavior as a function of dodecylamine concentration and pH are examined. The flotation response is characterized by adsorption and surface energy in the presence of amine. The methods of UV-Visible and FT-IR spectroscopy for adsorption and sessile-drop contact angle for surface energy estimation are employed. The results of wollastonite dissolution clearly showed its non uniform dissolution. The surfaces are depleted with calcium ions and became rich in silicon within 10 min of flotation time. Maximum flotation of wollastonite corresponds to a half monolayer coverage of amine, which is substantiated by the surface energy parameters. A good correlation between flotation, adsorption and surface energy as a function of amine concentration and pH was observed. The sudden increase in wollastonite flotation and amine adsorption at and above 5x10-5 M initial amine concentration is thought to be due to two-dimensional precipitation of amine on surface in accordance with the recent 2D-3D precipitation model of amine adsorption on silicate minerals.

Jan 1, 2003

By D. Tang

The froth zone in a flotation cell is recognised as a region which contributes to the overall flotation performance. Froth recovery is a measure of the efficiency with which the froth phase delivers particles arriving at the pulp-froth interface to the concentrate. Poor froth recovery in scavenger stages is generally attributed to poor froth stability. The key indicators of froth performance: froth recovery, entrainment and water recovery were measured in an OK3 pilot cell installed at a zinc concentrator in Australia and supplied with scavenger feed. Cell hydrodynamic and pulp chemical conditions during the operation of the cell were also measured as well as bubble growth across the froth phase. The objective of the work was to assess the impact of a number of commercial frothers on the froth performance in the OK3 cell and assess the suitability of using bubble growth as an indicator of froth stability.

Jan 1, 2014

By J. K. Afidenyo

Microbial pretreatment of a double refractory gold ore was investigated using a white rot fungus, Coriolus versicolor (ATTC 20869) to improve gold extraction. A series of preliminary tests were conducted to determine the amenability of the ore to fungus degradation. Pulp density, temperature, pH and retention times were the process variables considered. Both a single. Stage and two-step processes were studied to establish process conditions. During the single stage process, the ore was contacted with the fungus culture (biotic) for 3weeks at 30°C and pH 10.0. For the two-step process, the first step involves ore contact with the culture medium (abiotic) at 45°C and pH 10.0 followed by fungal contact (biotic) at 30°C. Results indicated that carbonaceous matter is not degraded but passivated by the fungus; as preg-robbing activities dropped significantly from 18.1% to below 1.0%. The single stage process resulted in higher gold recovery than the two-step process Gold ex-traction by cyanidation of the pretreated ore was 78.9% for the single stage compared with 15.0% for the untreated ore. In the two-step process, only 73.3% gold extraction was achieved. Application of the two step process conditions to a high grade flotation concentrate, resulted in 93.3% gold ex-traction as against untreated concentrate of 30.5%. The results show that the microbial pretreatment process degraded sulfide sulfur, passivated carbonaceous matter and enhanced gold extraction from double refractory gold ore and concentrate.

Jan 1, 2014

By S. J. Ma

With the very effective depressant and collector developed by China Bluestar Lehigh Engineering Corp (hereinafter referred to as LEHIGH), satisfied results are obtained from laboratorial beneficiation tests on phosphate samples from Karatau, Republic of Kazakhstan by the direct flotation process. In this paper the effect of single factors on performance of flotation is studied and their applicable ranges are proposed. The final test results are described as follows: As the feed contains 23.20 % P2O5, and 3.96% MgO, a phosphate concentrate assaying 29.77%P2O5 and 1.54% MgO is produced, and the P2O5 recovery in concentrate is 88.28%. The beneficiation tests make it possible to simplify existing technology with fine grinding-desliming, followed by reverse & direct flotation system and consequently improve the concentrate grade and recovery for the future beneficiation plant

Jan 1, 2014

By W. Krieglstein

Due to the natural variability of ores, it is necessary to carefully test flotation behavior of flotation cells before designing flotation circuits. For performing quick and versatile tests in the laboratory, Siemens developed a laboratory-size Hybrid Flotation Cell, which has been down-scaled from the 300 m³/h production cell to a 0.6 m³/h flotation cell. This small cell is being used as a test bed for technical and chemical concepts, the improvement of decisive components and the characterization of customer ores. In this study the evaluation results for Andean porphyry copper ores are shown. Total recovery rates of the order of 45 to 50 % have routinely been achieved in a single flotation cycle over a wide range of feed grades. In addition, the Hybrid Flotation Cell has proven to be particularly well suited for the flotation of fine particles below 20 µm down to below 1 µm, at high recovery rates and concentrate grades.

Sep 1, 2012

By A. Bahrami

Andalusite, silimanite and kyanite are polymorphs of aluminosilicate known as kyanite group. Minerals of this group are used in refractory. Sarband andalusite deposit is located in Markazi province in Iran. Mineralogical studies showed that the main minerals of this sample are andalusite (5%~10 %), mica, quartz and feldspar. Processing of the samples was carried out using two sizes, i.e. +500 µm and -500 µm. In the processing of +500 µm scrabble test was carried out on -4750 +500 µm and -2380 +500 µm. For -500+300 µm shaking table and magnetic separation were applied. For -300 µm fraction, flotation was carried out. The results of this tests showed that the processing of Shazand andalusite was not possible, because silica and iron impurities were diffused inside the andalusite mineral grains.

Jan 1, 2014

By Sergey S. Gudkov

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

Sep 1, 2012

By Leming Ou, Qiming Feng, Yiping Lu, Pengyu Zhang, Qing Shi, Kun Liu, Guofan Zhang

"This paper introduces the mineralogical analysis of certain polymetallic copper-zinc ore in China with the aim of improving the flotation process. The main valuable elements, mineral phases and compositions of run-of-mine ore were inspected by the X-ray Fluorescence (XRF) and chemical analysis. For a deep known of the old process defects, Mineral Liberation Analysis system (MLAs) was employed to investigate the minerals liberation degree of selected key slurry points. Analysis results show that the run-of-mine ore belongs to the original copper-zinc polymetallic symbiotic ore at low oxidative level, which mainly contains 0.16% Cu, 4.43% Zn and 0.88% Sn. Gangue minerals are mainly silicate minerals, and zinc mineral is sphalerite. MLAs test illustrates that about 86% sphalerite has been dissociated in zinc flotation feed. In the current flotation process, over grinding of sphalerite monomer and insufficient liberation of intergrowths are the key problems need to be solved imminently. Up to this point, a new process consisted of two steps roughing unit is submitted in this research. It contributes two positive effects on zinc flotation performance: (i) separating sphalerite monomer timely to decrease overgrinding; (ii) improving zinc minerals intergrowths liberation efficiency. Flotation results indicate that the zinc concentrate grade increased 0.90% and the recovery improved 0.96% in the new flotation processINTRODUCTION Mineralogical analysis mainly focusses on solving mineralogy problems in minerals processing, assisting in minerals behaviors prediction and control for separation engineering (Falkovich, et al., 2001; Hillier, et al., 2003; Schouwstra and Smit, 2011). Process defects searching becomes its ordinary work, and flotation optimization appears to be its targets gradually. For example, Lucky Friday mine company (Idaho America) fails to obtain qualified lead concentrate as the change of ore properties (Nadoll, et al., 2011). Mineralogical analysis ascertains that there are too many dissociated sphalerite, pyrite and gangue particles exist in lead concentrate. According to this, more cleaning units are added to solve problems effectively. Kanowna Belle mine (Australia) takes a flash circuit in operation successfully with the aim of optimize flotation process, under the helps of mineralogical analysis and industrial test (Newcombe, et al., 2013). Lotter N.O. (2011) gives a deep description on how mineralogical data assisting mineral processing engineers to design and optimize flowsheet. For decades, quantitative and automated mineralogy techniques (Andersen, et al., 2009; Gu, et al., 2012; Oghazi, et al., 2009; Yu, et al., 2007) get well developed and hugely improve the veracity and repeatability of minerals properties measurement. Among these, MLAs (Gu, 2003) provided by JKMRC (Julius Kruttschnitt Mineral Research Center) is critically acclaimed all over the world. This analysis system can measure mineral phases composition and content, particles size, minerals occurrence and liberation degree directly."

Jan 1, 2018

By L. Semushkina

Next generation flotation agents of KSK series for the concentration of complex copper-lead ores and the new ferromagnetic nanosized depressor of galena are introduced in this work. The feature of the KSK flotation agents is that they exhibit both frother and collector properties. KSK-6 can successfully substitute the widely used in Kazakhstani industry reagent ?-80 at the reduced consumption of butyl xanthate by 30 %. The new ferromagnetic nanosized depressor of galena, besides a low consumption rate of 100 g/t, also makes possible to exclude sodium sulfite (3-4 kg/t) and ferrous sulfate (5-6 kg/t) from the separation process, and receive high metal grade concentrates. Keywords: complex copper-lead ore, flotation agent, concentration method, ferromagnetic nanosized depressor

Sep 1, 2012

Separation performance of a Floatex Density Separator (FDS) has been studied both experimentally and theoretically. Experimental results reveal that at a lower bed pressure the FDS acts like a classifier. Higher bed pressure is required to attain the concentration effect as proper development of suspension density occurs under these conditions. It is seen that the size or density alone is not able to describe the partition fully. The terminal settling velocity, which includes both the size as well as the density of the particle can be a useful descriptor of separation in a FDS. While a narrowly distributed feed offers better performance of a FDS, a wide size distribution of feed results in large scatter in the terminal settling velocity distribution and renders the separation difficult. The closely sized feed enhances the density effect in concentration. A higher teeter water flow rate also helps in carrying larger-lighter particles to the overflow by increasing the cut off terminal settling velocity as it increases the net upward force. A detailed description of separation performance in a Floatex Density Separator has also been established from theoretical considerations. Separation performance of the separator is described using a simple slip velocity model. The model has been validated com-paring the predicted FDS performance results with those experimentally measured under widely different operating conditions.

Jan 1, 2014

By L. Simpson

South African is a repository of significant deposits of a variety of minerals. The Citigroup confirms this assertion with an estimate of in-situ valuation of US$2.5 Trillion. The mining sector plays an important role in the South African economy. In addition to the mineral resource base South Africa has other comparative advantages. Firstly, South Africa retains major mining companies that participate globally, including Anglo American, Goldfields and De Beers. Their global involvement offers much to the local mining sector and the broader economy. Secondly, government established research councils. The Council for Geoscience (CGS) was established to manage the Geological Survey of South Africa, including the reduction of geo-scientific investment risk. The Council for Scientific and Industrial Research (CSIR) promotes industrial development, including mining technology development. Mintek undertakes mineral research from mineral examination of ores, to extraction and refining technologies and manufacture of end products. Thirdly, South African universities teach and conduct research along the mineral value chain. They have increased their minerals graduates? capacity, thus advancing knowledge and skills. Knowledge and technical progress are behind productivity growth and emergence of competitive advantage. The research and development (R&D) capabilities of industry, science councils and universities, working in unison, will enhance the competitiveness of the South African mining industry. The National System of Innovation (NSI) requires multi-disciplinary, collaborative research. Key R&D elements, including skills and expertise, funding and facilities, must be available to implement a long-term national strategy or programme. Improved international collaboration and partnerships between government, academia and industry driven human resource development (HRD), ultimately develop the critical mass for inter-generational skills requirements. This trend requires an expansion of research collaboration programmes. Decisions involving investments and collaborative actions pertaining to R&D in the sector necessitate an analysis of the South African mineral value chain R&D capability. This paper analyses the evolution of R&D capability from exploration to refining, tertiary education, science councils and industry. The political economy of the evolution of this capability is analyzed in relation to the central role that the South African government plays in creating an appropriate supporting environment and related initiatives to enhance R&D and innovation. Keywords: research and development (R&D), science councils, universities, industry, innovation policy, South Africa

Sep 1, 2012

By K. Trybalski

Facing the optimization activities, which purpose is to minimize the copper processing costs, the main sources of their occurring were presented. In this purpose, the costs analysis was performed, divided to individual standings, for one of the polish copper beneficiation plants. It was proved, that the main component of the copper beneficiation costs is energy consumption, generated mainly in grinding and classification node, particularly by operating mills. The technological system ? grinding and classification node ? in KGHM Polska Miedz S.A., ZWR region Lubin was then selected to investigation. To evaluate the grinding and classification node, the energetic factors W were proposed, calculated on the basis of the energetic-technological data of process, given by node monitoring system. The correctness of the energetic factors selection to evaluate the work of this node and their practical application in industrial conditions was experimentally proved in other technological object. The selected technological object ? grinding and classification node ? was then mathematically modeled and optimized. The calculated energetic factors were the basis to build mathematical models, identifying industrial copper grinding and classification process. The models described correlation and character of dependency between factors and energetic-technical data of the process. These were regressive and neural networks models. On the basis of factors models, the optimization tasks were determined, which purpose was to select the optimal points of grinding and classification node work. Also, the estimated economical effect, possible to achieve after introduction of given monitoring values to grinding and classification node optimization system, was presented.

Jan 1, 2014