Search Documents

By Sergio Castro, Janusz Laskowski

In the flotation in highly concentrated electrolyte solutions not only ionic strength but also chemical composition, flotation pH and mineral properties play an important role. As a result an improvement or depression may be observed. A strong improvement in the floatability of hydrophobic bituminous coals and other inherently hydrophobic minerals is characteristic for the "salt flotation process", which is carried out in concentrated electrolyte solutions at natural pH and without addition of any flotation reagents. However, pH is a key factor when saline and hipersaline waters with hydrolyzing metallic ions are used as process water. In the case of flotation of Cu-Mo sulfide ores in seawater, molybdenite is strongly depressed by the Mg2+ hydrolysis products when pH is raised to depress pyrite. Process water with a high content of Mg2+ and Ca2+ ions, and this also includes seawater, have deleterious effect on the anionic flotation of industrial minerals with fatty acids. The flotation of potash ores is carried out in NaCl-KCl saturated brine (6-7 mole/L of NaCl and KCl) with the use of long-chain amines. Such a high electrolyte concentration changes dramatically the amine Krafft point making the collector insoluble in brine; its mode of action entirely differs from that in conventional flotation processes.

Jan 1, 2014

By Liu Jin

"In order to reduce the dosage costs and increase the economic benefits of a full floating process in a low grade complex multi-metals W-Mo ore, based on the study of the magnetic characteristics of the main gangue minerals, a joint process by magnetic separation and floatation technology is adopted. The first step of the flowsheet is to recover magnetite by magnetic separation, then remove the magnetic gangues by high gradient magnetic separation (HGMS) and finally recycle the W-Mo from the magnetically separated tailings by flotation. Results of the lab experiment show that in comparison with the full flotation process, the floatation feed tonnage of the combined flowsheet are only 46%. The grade and the recovery of Mo in the rough Mo-Bi concentrate is similar with the original one while the WO3 in the tungsten rough concentrate is increased from 3.85% to 6.64%. The dosage costs are reduced by 53%. The new process can significantly improve the plant economically. INTRODUCTION With the continuous exploitation of scheelite resources, the easily obtained resource is gradually depleting. The ""lean, fine and complex"" scheelite resource has become the main research object of tungsten beneficiation (Lou et al., 2010) (Xiao et al., 2013). The passive situation of tungsten beneficiation can be reversed by enhancing technological innovation and investment in science and technology, changing the business philosophy and mode of production, optimizing the process structure and process conditions, improving various technical indexes and reducing production costs of reagents, which will maximize economic benefits (Jiang et al., 2012 ) (Zhu et al., 2016). A polymetallic deposit of tungsten molybdenum bismuth original process adopts a full flotation process. With the expansion of stope mining, the content of valuable metals in the ore continues to decrease, resulting in a high cost per ton of concentrate produced and a low output value (Li et al., 2015)."

Jan 1, 2018

By Stephen Simukanga, Jewette Masinja

"Mining has been going on commercially in Zambia for over 100 years. The backbone of the mining industry has been copper production and its by-products of cobalt and gold. Over these years, the mining industry ownership structure has swung from private ownership to state ownership in 1972, and back to private ownership in 1995. Environmental management was first introduced into the body of Zambian legislation in 1991 through the promulgation of the Environmental Protection and Pollution Control Act (EPPCA). The Act’s main functions included the protection of the environment and control of pollution, and in particular to provide for the health and welfare of the people, animals, plants and the environment in general. This Act, was replaced in 2011 by the Environmental Management Act (EMA). The new Act has a number of new elements including: mainstreaming environment in national planning, it provides for the domestication of multilateral environmental agreements, enhances public participation issue, creates a central environmental information depositary, elaborates access to information principles, establishes an environment fund, creates enforcement orders, provides for both Zambia Environmental Management Authority and members of the public to sue for damages following environmental pollution, and provides for the appointment of honorary Inspectors. In addition to this, the Mines and Minerals Act of 1995 provided, for the first time, a section on environmental management in the mining sector. This section also created the Environmental Protection Fund (for mining), and made it obligatory to undertake environmental impact assessment before mining permits could be issued. The Environmental Protection Fund has now been established, as provided for by the law, and currently has more than USD9.0 million in the account. Secondly, environmental auditing is now being carried out annually on mines around the country, the effect of this has been a significant improvement in the environmental management of mining in Zambia. This paper looks at the response of the Zambian mining sector to these pieces of environmental management legislation, and the direction that the mining sector is expected to take on environmental management going forward."

Jan 1, 2014

By K. Kiangi

On installing the Metso Superior MK 54x75? primary gyratory crusher in Nkomati mine the crusher experienced severe power spikes greater than 1000kW which subsequently led to the crusher tripping under load while processing some of Nkomati?s MMZ ores. Likewise significant losses in throughput were also experienced while processing some of Nkomati?s MMZ ore types. Interestingly the crusher was capable of processing the PCMZ ores without experiencing any power spikes or losses in throughput. Investigations into the challenges faced by the crusher while processing Nkomati?s MMZ ores were conducted using the DEM model in conjunction with the fast breakage model present in Metso?s High Fidelity Simulator. The intentions of the study were to establish the most suitable operating conditions or cavity design that would potentially enhance the performance of the crusher. Likewise an understanding of the effects the feed conditions (size distribution and hardness) had on the crusher?s performance was established. Ore characterization tests were conducted on Nkomati?sPyroxenite, Diabase, Calc silicate and quartzite ores which were from Nkomati?s MMZ ore body. The ore characterization tests conducted were drop weight tests, slow compression tests and elastic modulus tests. Four simulations were conducted used the existing cavity design with various open side settings (OSS) and throws. This established the effects of changing the crusher?s operating conditions on its performance. Four additional simulations were conducted on two cavity designs with reduced volumes. This established the effects of changing the crusher?s cavity design on the crusher?s performance. Thus through the simulations a better understandings of the impact of the crusher design, operating conditions and feed conditions on the crushers performance. Furthermore an analysis of the crusher?s performance was made which was used as a basis for comparisons with the base case simulation. Keywords: crusher, discrete element method, simulation, ore characterization

Sep 1, 2012

Producing robust agglomerates with desirable structural properties is the key to success of the heap leaching of complex, low-grade nickel laterite ores. Mechanically strong but porous agglomerates with narrow size distribution (e.g., 5 ? 40 mm) are required to build permeable and perennially stable heaps of 4 ? 10 m height. The characterization of granules? microstructure is essential for greater understanding and correlation with the concomitant mechanical properties and robustness. In this study, we used non-destructive, computed X-Ray tomography analyses and scanning electron microscopy (SEM) in tandem with conventional compressive strength,and integrity/stability tests to draw links between nickel (Ni) laterite agglomerate strength/stability, internal microstructure (e.g.,porosity, inter-particle bridges) and binder type. It is shown that binder composition (e.g., tap water vs. 30% w/w H2SO4) and post-agglomeration drying both significantly impact on granules? physicochemical and microstructural properties. Acidic binder, in contrast with tap water, leads to significant incongruent leaching of different species from particles during ore-binder mixing and agglomeration. Upon wet agglomerate curing, solidified/recrystallized leached species form strong intra-granular solid bridges which, lead to greater compressive strength of dry agglomerates. Structural stability/integrity of cured agglomerates in acidic solution, however, decreases dramatically due to greater porosity and acid solubility of intra-granular solid bridges. These findings are useful in shedding more light on agglomerate structure characteristics and their optimization for enhanced column and heap leaching with concentrated sulphuric acid.

Sep 1, 2012

By E. V. Zelinskaya, V. U. Starostina

"The Irkutsk region is a raw material region. There are a lot of big enterprises for extraction and processing of oil, gas, coal, iron, gold and rock salt. Besides of it, refractory clays, limestone, mica, gypsum and talc are mined in the region. The most important type of mineral raw material is a gold. More than 8.5% of the total mining in the Russian Federation is extracted in Irkutsk region. It is about 0.7% of the world production. The environmental problems of mining and processing enterprises are a complex set of issues that requires of the searching of effective methods to be solved. One of the key environmental problems remains the reduction of waste generation and the introduction of environmentally safe waste management. After analysing different methods of environmental impact assessment it is established that the method of Life Cycle Assessment is one of the most effective methods for mining production. This method base? on the material balance of flows of raw materials, products and waste. The method of Life Cycle Assessment allows to identify the effects of environmental pollution under the influence of mining and processing at a quantitative level and to show real quantitative forecasts of the possibility of managing the flows of raw materials and waste.INTRODUCTION The Irkutsk region is a raw material region. There are a lot of big enterprises for extraction and processing of oil, gas, coal, iron, gold and rock salt. Besides of it, refractory clays, limestone, mica, gypsum and talc are mined in the region. The most important type of mineral raw material is a gold. More than 8.5% of the total mining in the Russian Federation is extracted in Irkutsk region. It is about 0.7% of the world production. The main provider of precious metal is the Bodaibo region. This is a main location for the major ore companies such as “Vysochaishy”, which produces about 5.0 tons a gold per year; “Pervenets”(PJSC Polyus, the largest gold producer in Russia) - 4.5 tons/year, “Druza” - 0, 5 tons/year. Placer gold is extracted by more than 40 enterprises. In connection with this, there are many plans about a building of new and reconstruction of concentrating factories. Consequently, an increase in the volume of processing is expected. The main projects are the construction of a new mill of the Mining and processing plant GOK “Vysochaishy” with a capacity of 2.6 million tonnes of ore per year; the development of the “Uhakhan” gold-field - 23 km from the “Goltsa Vysochaishy” gold-field; the opening in the Bodaibo region the next parts of the gold-deposit ""Pervenets"". Additional, the growth in a gold production can be achieved by a store of gold in the “Sukhoi Log” deposi"

Jan 1, 2018

By Q. Cui, Z. G. Song, S. S. Lin, S. Q. Li, S. S. Lu, G. B. Zheng, A. J. Ren

"Mine tailings is one of the most important bulk industrial solid wastes, but its rate of comprehensive utilization is relatively low. Efficient separation, recovery and utilization of the valuable components is one focus of the comprehensive utilization of tailings. Beneficiation recovery of the valuable minerals is the most direct comprehensive utilization method for tailings. There are generally different kinds of nonmetallic minerals contained in the nonferrous metal mine tailings, which are secondary mineral resources waiting for further developing and recovery. Comprehensive utilization test studies on fluorite in tungsten beneficiation tailings and feldspar in molybdenum beneficiation tailings have been carried out by author and good test results are achieved. Some of the technologies developed in the test study have been applied in industrial productions, which have been working well. The economic, social and environmental benefits are remarkable. Our test studies and some production practices will be summarized and current situation and existing problems of comprehensive utilization for nonferrous metal mine tailings will also be discussed. Assumption and prospect for the future study on comprehensive utilization of nonferrous metal mine tailings will be brought at last.INTRODUCTION Mine tailings is one of the most important bulk industrial solid wastes, but its rate of comprehensive utilization is relatively low. Efficient separation, recovery and utilization of the valuable components is one focus of the comprehensive utilization of tailings. Beneficiation recovery of the valuable minerals is the most direct comprehensive utilization method for tailings. There are generally different kinds of nonmetallic minerals contained in the nonferrous metal mine tailings, which are secondary mineral resources waiting for further developing and recovery. Comprehensive utilization of nonmetallic minerals of nonferrous metal mine tailings not only can improve the value of the ore but also reduce the stock of tailings, being the key to reduce emissions at source for exploitation of nonferrous mineral resources (Cai, Yang, 2000)."

Jan 1, 2018

By Bruno Michaux, Markus Reuter, Martin Rudolph

"It is relatively well-established in the literature that the flotation of calcium minerals using fatty acids as collector is very sensitive to the process water composition. In particular, hard waters have often been reported to strongly reduce the target mineral recoveries due to the formation of insoluble compounds such as calcium and / or magnesium dioleate, thus reducing the amount of collector available for adsorption onto the mineral surface. In this study, the flotation of a fluorite pre-concentrate was performed with tall oil, an industrial collector essentially containing fatty acids. The tests were performed in a variety of synthetic waters to simulate multiple degrees of water hardness, and to differentiate the role of magnesium and calcium ions on the flotation performance. The flotation tests revealed that, under the studied conditions, a significant difference between flotation in calcium-rich and magnesium-rich waters was observed, suggesting strong ion-specific effects in the system. Specifically, calcium-rich waters slightly improved the fluorite recovery, whereas magnesium-rich waters caused a decrease in recovery by as much as 20%. This paper is focused on the flotation kinetics aspect of the system. This approach highlighted the interesting finding that calcium ions did not simply increase the fluorite recovery, but also significantly increased its flotation kinetics. The magnesium ions, on the other hand, had the exact opposite effect.INTRODUCTIONAs the mining industry is facing an increasing number of issues related to its fresh water consumption, the idea of using alternative water sources for mineral beneficiation is gaining significant momentum. As a result, a proper understanding of the role of water chemistry in flotation is becoming more and more urgent, leading to an increasing number of studies on this topic."

Jan 1, 2018

By P. Ying

An auxiliary system connected with SEM-EDX for rapid identification of mineral and rock sample has been developed. With the aid of a synthetic spectrum library created, using the compare and match techniques provided by INCA software in EDX the mineral or rock sample names for refer-ence can be given at the same time analyzed.

Jan 1, 2014

By B. P. von der Heyden, P. Neethling, M. Tadieb, L. Babedi

The effects of trace element substitutions in sphalerite mineral structure on optimised floatation response have, as yet, not been fully constrained or fully understood. To further this important field of study, this contribution focusses specifically on mineral and surface chemistry, and electro-chemistry of Cd- and Co- substituted synthetic sphalerites using Raman spectroscopy and Zeta potential experimentation. Raman spectroscopy illustrates that the presence of these impurities results in the introduction of a new mode, the relative intensity of which can be correlated (Cd r2=0.95 and Co r2= 0.99) to the dopant concentration. Comparison to X-ray Diffraction results measuring the unit cell parameter further shows that this relative intensity (Cd r2=0.81 and Co r2= 0.99) may provide insights into the degree of lattice strain within the mineral structure. The zeta potential distribution of an un-activated Cd-sphalerite show no detrimental effect as function of Cd content. Although the iso-electric point shifted from 2.45 at 1 wt.% Cd to 2.69 at 3.68 wt.% Cd, the zeta potential remained negative at alkaline media. Conversely, cobalt at low concentration of 0.36 wt.% had a detrimental effect on the surface charge, resulting to a close to neutral zeta potential at different pH. The adsorption of Cu ions on the surface of Co-bearing sphalerite conditioned in an alkaline media slightly increases the zeta potential of Co-sphalerite. While the Cd-bearing sphalerite decrease in negative zeta potential at >1 wt.% Cd indicating a complete exchange between Cu and Zn. The results presented herein illustrate that, based on the chemical nature of the substituting metal; sphalerite will exhibit multiple response to flotation reagents. Maximum recovery of zinc can thus only be achieved through multidisciplinary study and fundamental understanding of the effects of cation substitution on mineral structure and surface chemistry, the latter necessarily affecting the floatation response.

Jan 1, 2018

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 Neill Bartie, Jacques Eksteen, Sharif Jahanshahi, Shouyi Sun

The gradual increase in Cr2O3 levels of UG-2 ores has become a matter of concern for platinum producers in South Africa due to the formation of chromite spinels in melters. The effect of bulk FeOx/MgO ratio, Cr2O3, temperature and oxygen partial pressure on phase stability and composition in the system FeOx-MgOSiO2- Cr2O3-Al2O3-CaO has been studied between 1400°C and 1600°C using the drop-quench technique. An increase in temperature was found to result in a decrease in [Fe/Cr]spinel. An increase in bulk FeOx/MgO caused Mg, Al and Cr in spinel to decrease, forming more magnetite relative to other spinels. [Fe]spinel decreased and [Cr]glass increased with a decrease in oxygen partial pressure.

Jan 1, 2003

By M. K. G. Vermaak

Kimberlite weathering has been a topic of ongoing research within De Beers for many years. Using kimberlite weathering as an alternative to crushing has many advantages e.g. power and reducing diamond breakage. Weathering could also possibly be used in conjunction with crushing just to weaken the material and reduce power consumption. These forces have driven current research to investigate whether kimberlite weathering could be utilised for these reasons. Weathering in this context does not refer to weathering over long period of time but rather to disintegration of the material in aqeous media in relative short time periods. Previous published work discussed that the presence of smectite renders kimberlite weatherable and that the amount of smectite determines the rate of weathering (Morkel and Vermaak, 2006). The current work investigates whether cation ex-change or the adsorption of organic species in the smectite interlayer could influence the observed weathering behaviour. The results show that cation exchange does take place in the presence of cation species and that the weathering behaviour can be drastically improved with especially Cu2+ cations. Concentration and time effects of the weathering was also investigated. Weathering tests with organic species such as ethanol, methanol, edta, pentanol, butanol, acetic acid and oxalic acid was performed. The results show that organic species does improve weathering but under these testing conditions was not as effective as cations.

Jan 1, 2014

By H. Allenius

Today, most requests for quotations force all bidders to follow the bid document to the letter. The choice is then made based on price since it is the only difference in technically identical offers. However, clients allow and even encourage suppliers to come up with alternatives. Overall economy again, is much more than low investment costs. Operation costs may affect the economy of a project far more than a million saved in investment. There is almost always the choice: Should we go for the cheapest solution or should we go for the most economical solution? We strongly recommend the study of the long-term effects on investments as they often surpass any apparent savings in capital expenditure. With high operating costs, time is never on our side. Almost all relevant inputs and outputs in a concentrator have a value that can be expressed in a suitable currency. Unit prices may differ substantially from one operation to the other, but everything has a price tag and globalization has made it possible to move both goods and services to almost any place in the world. Even a rather simple exercise can give a good indication on which process improvements are worth pursuing when investing in new systems or equipment. The ones that do not qualify, as money earners, will naturally appear as clearly. No ?rocket science? is required, just process knowledge, practical experience, an open mind and some common sense and the reward may be the difference of having a good or an excellent project. The model we have developed can be made as detailed as required, but we do not recommend too much detail, as it sometimes tends to distract work and obscure the important issues. Two different process solutions compared in a simplified example illustrate the importance of evaluating a project based on its long-term effects rather than focusing on the investment costs only.

Jan 1, 2014

By Ibrahim Alp, Ersin Yazici, Oktay Celep, Haci Deveci

Low extractions (<80%) in cyanide leaching impose the application of physical and chemical pre-treatment methods (e.g., ultra-fine grinding, roasting, alkaline leaching) prior to cyanide leaching to achieve acceptable recoveries. The effectiveness of the selected pre-treatment method is linked intimately with inherent mineralogical properties of ore. In this study, a refractory silver ore assaying 145 g/t Ag was subjected to various pretreatment tests in an attempt to eliminate its refractoriness. Direct cyanidation of the ground ore (d80: 65 µm) produced a low silver extraction of only 29.5% over 24 h indicating its high refractoriness. Previous studies have shown that silver occurs mainly as Sb/As containing sulfide minerals such as pyrargyrite (Ag3SbS3), tetrahedrite (Cu12Sb4S13) and proustite (Ag3AsS3), which do not respond well to cyanide leaching. Also, silver-containing minerals are closely associated with and/or encapsulated in other mineral phases that can restrict the contact of cyanide with silver. Therefore, alkaline leaching (using 3 M of Na2S, NaOH or KOH solution) and ultra-fine grinding as pre-treatment methods were tested to improve the extraction of silver. All the alkaline leaching tests were carried out for 3 h at800C. Neither NaOH nor KOH leaching produced the desired effect on the extraction of silver (i.e., ~30%). Even, a sharp decrease in the extraction of silver (i.e., 10%) was observed in Na2S leaching. On the other hand, ultra-fine grinding (UFG) (d80: 3 µm) substantially improved the extraction of silver in cyanide leaching (95% Ag at 24 h after UFG). It can be inferred from these findings that the refractoriness of the ore is essentially physical in character (i.e. the encapsulation of silver presumably in non-sulphide minerals such as barite and quartz).

Jan 1, 2014

By Jonas Addai-Mensah

In this paper, the results emerging from the several basic and applied studies performed to provide fundamental understanding of the interplay between clay pulp chemistry, orthokinetic flocculation performance, particle interactions, applied shear and dewaterability of fine clay mineral dispersions are presented, reconciled, and discussed. Modification of pulp chemistry and behaviour was achieved by using kaolinite and Na-exchanged (swelling) smectite clay minerals, divalent metal ions (Ca(II), Mn(II)) as coagulants and high molecular weight, anionic polyacrylamide copolymers: carboxylate substituted (PAM A) and 2-amido 2-methyl propane sulphonate (PAM S) (PAM S), non-ionic polyacrylamide homopolymer (PAM N) and non-conventional, non-ionic polyethylene oxide (PEO) as flocculants. Clear links between pulp interfacial chemistry, particle interactions and dewatering behaviour, resulting from the influence of hydrolyzable metal ion, pH, temperature, polymer structure type and shear, are established. Optimum conditions for improved, orthokinetic flocculation performance of negatively charged clay particles, reflecting faster settling flocs (>10 m/h) comprised: (i) coagulation, (ii) moderate agitation rate, (iii) shorter agitation time and (iv) anionic rather than non-ionic PAM. The optimum flocculation conditions did not, however, have a significant impact on the final sediment solid content of 20 ? 25 wt%. Further application of shear to pre-sedimented pulps improved consolidation by 5 - 15 wt % solid. Application of the findings and new knowledge gained to real plant tails? case studies for marked improvement in dewaterability through thickening is demonstrated.

Sep 1, 2012

By James A. Finch

"Developed countries are in the midst of re-structuring education in minerals-related disciplines as raw materials, once vital to wealth generation, contribute progressively less to the economy. The changing circumstances mean institutions must justify mineral processing by new criteria. After considering what a mineral processor needs to know the ways to deliver are considered. Taking twenty graduates per year to illustrate, one institute could justify this number as a program in a department or school (of whatever grouping of disciplines). A strong research component would make the package additionally attractive. Divide among four institutions and mineral processing is best served in a research centre with delivery taking advantage of multi-centre and distance learning opportunities.INTRODUCTIONThis is one of five plenary lectures at the Congress. I may have preferred a technical subject, as that is what occupies most of my thinking hours, but it is reasonable as an academic that this topic should come to one of us. The fact the topic has not been high on my agenda may provide one advantage: that I can suggest directions free of pre-conceived notions, just as when reviewing the background to a technical article the temptation to select in support of one?s interpretations is resisted. The trick will be to add something new.One reading of the title seems to query whether mineral processing education has a future. (I will refrain at this juncture from defining mineral processing and assume for now we share an understanding of the term.) The proximity of natural and human resources led to the Industrial Revolution and the interaction continues to stimulate and sustain industrial and economic development in many parts of the world. The search for raw materials has historically played a key role in opening frontier areas, with undersea and outer space next. The reason is obvious: raw materials along with food and energy underpin society. Thus mining will remain part of human activity along with the need to pass on the knowledge and skills.What happens over time is resource relocation. Raw materials become exhausted in one area to be replaced by sources elsewhere; the demand for some materials lessens while growing for others. Educational institutions can find themselves with the wrong geography or with staff focussing on the wrong subjects. When this happens the restructuring produces much discussion. This is where we are in parts of the world. Japan, Western Europe and the United States are the prominent examples (Dowd, 1998; Flemings and Suresh, 2001; McDivitt, 2002). Mineral processing is becoming a series of courses in related disciplines: resource engineering, environment engineering or materials engineering. The start of the transition is evident in Canada and Australia, perhaps earlier than expected given the contribution of raw materials to their economies. A common backdrop in the developed countries is social pressure to reduce the impact of the ?untidy? aspects of life, and that includes mining. (This is not new: in classical times the mine face was the preserve of slaves and convicts.) These values are exportable, potentially affecting recruitment into mining schools everywhere."

Jan 1, 2003

By Jie-Liang Wang, Yongdan Cao, Zhao Cao

"The effect of ethylenediamine tetraacetic acid (EDTA) on flotation separation of fluorite from bastnaesite and its selectively depression mechanism on fluorite were studied by single mineral flotation, artificial mixed minerals flotation, solution chemistry analyses, Zeta potential and XPS measurements.The results show that fluorite can be deeply depressed by EDTA while the flotation of bastnaesite is almost unaffected when octanohydroxamic acid (OHA) is used as a collector. The separation index (SI) between bastnaesite and fluorite increases with the dosage of EDTA, SI can be raised from 1.18 to 12.66 when EDTA dosage increases from 0 to 2×10-3mol/L.Solution chemistry analyses show that EDTA is able to convert the Ca(OHA)2 hydrophobic precipitation on fluorite surface to a soluble Ca-EDTA complex but cannot complexly dissolve the Ce(OHA)3 precipitation on bastnaesite surface. Therefore, the Zeta potential of OHA conditioned fluorite can be reduced significantly by EDTA while the reduction degree to Zeta potential of bastnaesite is relatively low. XPS measurement shows that EDTA removes the chemically adsorbed OHA from fluorite surface but has little effect on the adsorbed OHA on bastnaesite surface. As a result, fluorite can be selectively depressed by EDTA in bastnaesite flotation, which behaves an important industrial application prospect in rare earth ore flotation.INTRODUCTIONNowadays, Rare earth elements (shortened as RE) and compounds are of significant importance for a range of rapidly expanding industrial applications including catalysis, metallurgy, renewable energy, and special materials due to their unique electrical, magnetic, optical and chemical properties [1]. The seventeen RE elements, including the lanthanide-group fifteen elements, yttrium and scandium, could be divided into three groups, i.e., light, medium and heavy RE elements based on the different solubility of RE sulfates [2]. Bastnaesite ((Ce,La)CO3), containing approximately 75% REO, is one of the most important light RE minerals [3]. Flotation is the common method to recover basetnaesite [4-6]. Nonetheless, basetnaesite is often associated with calcium-bearing gangue minerals such as fluorite, and the separation of basetnaesite and fluorite by flotation is usually difficult due to their similar surface properties and therefore floatability [7-9]. Therefore, research on high selective flotation reagents of bastnaesite over gangue minerals has attracted a lot of attention [10]."

Jan 1, 2018

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

Sep 1, 2012

By Markus A. Reuter, Jacques J. Eksteen

The modelling of bath type furnaces tends to be either fundamental in nature or total empirical "black box models". While models of the first kind are robust, they tend to lack accuracy, in cases where they are to be used for process control, and may take an overly long in development time. On the other hand, black box models tend to lack robustness of prediction for all circumstances and tend to be limited to interpolate based on historical data. While this may very often provide short-term accuracy, the models may have problems with stability in the long term. Moreover, the model structure may not reflect any of the fundamental properties of the system and remains opaque to fundamental analysis. The aim of the model development is in obtaining a model that have robustness, high accuracy, a short development time and which is adaptive to a changing environment. The models are specifically developed for on-line decision support or control of furnaces. The modelling approach is evaluated for a chromite bath smelting furnace. The role of systems analysis, mass balance smoothing, thermodynamic analysis are integrated into one generic algorithm for bath type furnaces. Therefore, this paper argues that to understand complex metallurgical furnaces a hybrid approach is the only method to fully grasp the intricacies of metallurgy, to improve operations, economics as well as environmental performance.

Jan 1, 2003