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By G. H. Li

Preparation strontium carbonate with celestite concentrate by flotation is studied by agglomeration-reduction roasting process. It is shown that, the drop strength of green pellet is greater than 4 times?(0.5m) -1 under the balling conditions of moisture of 9% and time of 18~20min. Lignin xanthate obviously improves the ballability of the celestite concentrate due to the increase of surface hydrophilicity, therefore, the balling rate is increased, as well as green ball strength. The drop strength of 7 times?(0.5m) -1 can be obtained when the lignin xanthate dosage is 0.5%~1%. Reduction roasting with anthracite shows that the SrSO4 conversion is 82%~83% for celestite concentrate pellet, under the optimal conditions of roasting temperature of 1100~1150? and time of 30min, and it is 10% higher than conversion of celestite lump under the same conditions. The strontium carbonate are prepared after roasted pellets are leached, purified and carbonated, and the SrCO3 content is higher than 97% , while the content of CaCO3 is less than 0.3%.

Jan 1, 2014

By A. Güney

Currently, recycling technologies use relatively homogeneous plastics because hand-sorting waste feed is too expensive. Many promising technologies for separating mixed thermoplastics are being investigated, but they are still uneconomical and unreliable. Burning plastics for recycling is not used because of poisonous gases released when their burning. PET and PVC cannot be separated using conventional gravity separation techniques because their specific gravities overlap; PET density changes from 1.33 g/cc to 1.37 g/cc and PVC density is between 1.32 g/cc and 1.37 g/cc. For this reason, plastic recycling needs new techniques. Among these techniques froth flotation, also used in mineral processing, can be useful for its cost and simplicity. In this method, a plastic is selected from mixture, tried to regain its natural property, hydrophobicity. In this study the experiments were applied by using plasticizer reagents to make the selected plastics hydrophobic and us-ing NaOH to render the other hydrophilic. Post-consumed PET and PVC are evaluated by concerning the effects of selected parameters (particle size, concentration of plasticizer reagent, amount of NaOH, conditioning time and the effect of conditioning temperature). At the end of the experiments, optimum parameters for selective flotation of PET from PVC was found as particle size of -4.76 + 3.36 mm, NaOH amount of 30 kg/t, conditioning temperature of 75°C, conditioning time of 30 minutes, reagent amount of 300 mg/L. Consequently, PET was re-covered with 99.7% purity and 57% efficiency.

Jan 1, 2014

By Q. Zhang

Phosphate tailings through Flotation contains large amount of dolomite which is difficult to be separated from apatite. In this present research, phosphate tailings is recycled by Flotation i.e. re-processing. High-purity dolomite with purity as high as 91.17% is seperated, which contains 19.82% of MgO. The results of orthogonal test show that the effect of various levels of different factors on the high-purity dolomite floatated. Future utilization of purified dolomite is also discussed: magnesium fertiliser especially magnesium phosphate is expected to be an ideal product from high-purity dolomite.

Jan 1, 2014

By A. Ceylan

Pyrite is present as a gangue mineral in most of complex sulphide ores and most of time it is removed as a tailing. However, beneficiation of pyrite from tailings could be important because of its economical value and for the environmental concern. This paper presents a research for the enrichment of pyrite from copper plant tailings, Siirt-Madenköy/Turkey, by flotation. Siirt-Madenköy copper mine is operated by Park Electric Production Mining and Industry since 2005. In order to obtain the pyrite from Siirt-Madenköy copper plant tailings, laboratory test work has to be done to determine the type of reagents, the flowsheet, and the size of plant. The objective of the company is to develop a pyrite flotation circuit for concentration of pyrite from tailing dam to obtain 500.000 tons/year pyrite concentrate. There are about 3 million tons tailings that containing pyrite in the tailings dam. Experiments were carried out with three different types of tailings from the plant and the pyrite concentrate with 46% Fe and 90% recovery has been obtained. Therefore, this study shows that high grade pyrite with high recovery can be recovered from the tailings.

Sep 1, 2012

By G. Aguilera

The mineral suspensions do not present a newtonian behavior as their continuous phase; they can be pseudoplastic, dilatant, or both. The viscosity becomes as the most important rheological variable because the different industrial processes involve a wide variety of rheological scenes, with a specific rheological behavior for each one. Some authors have tried to model the viscosity of suspensions considering the volumetric fraction of solids and others have also kept in mind the size of the particles (Einstein, 1906; Batchelor, 1977; Jinescu, 1974; Krieger and Dougherty, 1959; Tangsathitkulchai and Austin, 1988). Others consider the shear rate (Cross, 1965; Hershel-Bulckley, 1926; Bingham, 1916, etc). However, none of the models is able to simulate the viscosity involving the physical, chemical and mechanic factors at the same time for crowded suspensions. A new model based on Neural Networks is presented, taking into account all the variables of ceramic clay suspensions and chemical additives. Keywords: viscosity, clay minerals, neural networks, simulation, mathematical function

Sep 1, 2012

By Gustav Hawlitschek, Henrique Kahn, Carina Ulsen, Renato Contessotto

"The problems related to waste dumping increased with the growth and development of large cities. In the U.K., more than 50% of landfill waste comes from construction use and the U.S. alone produces around 200 to 300 million tons of CDW annually. The exhaustion of natural sand deposits close to large urban centres stimulates the recycling of construction and demolition waste for the production of recycled aggregates as a construction material. This paper presents a flowchart for the production of recycled sand with low porosity and regular shape by the selective removal of the cement paste attached to recycled aggregates. The products characterization was carried out by the determination of the particle size and shape distribution, chemical and mineralogical composition, heavy liquid mineral separation and quantification of all present phases using a scanning electron microscopy with automated image analysis (SEM-MLA). The comminution of CDW by vertical shaft impact crusher made possible the production of a lower porosity recycled sand. The heavy liquid mineral separation showed that the proportion of low porous phases (d>2.5 g/cm3) is very high, exceeding 70% of the weight, encouraging further mineral processing separation to obtain a fine recycled aggregate with less cement paste content. The mineralogical characterization by XRD and SEM indicates that the main phases are tectosilicates, phyllosilicates and calcite which one can be attributed to both calcareous aggregate and cement paste. The precise quantification of cement paste and calcite/dolomite alone is just possible by automated image analysis. The characterization results demonstrated that proportion of phases with no cement paste attached increases progressively in denser products. The results of heavy liquid separations and image analysis are comparable and automated image analysis can be used for the characterization of phase content and their main associations."

Jan 1, 2014

By M. E. Ramírez

In this research bioleaching or extraction of iron present in a kaolin from La Virgen mine, Anti-oquia/Colombia, was carried out. Organic acids produced in SF with Aspergillus niger were used in the process. The fermentation process was carried out in 3 L aerobic stirred bioreactors, at a temperature of 30 °C, a stirrerd speed of 700 rpm, an initial pH of 4 and a fermentation time variable between one to 8 days, obtaining broth fermentation samples daily per bioreactor. For iron extraction, fermented broth from second to sixth day of fermentation was evaluated and it was found that the fermentation broth of the third day showed a larger potential for iron removal, 786 ppm, by using kaolin with an initial iron content of 1401 ppm. A set of tests using commercial organics acids such as citric acid and oxalic were carried out because those were found in the fermentation broth and it was found that oxalic acid presented three times more iron removal than citric acid.

Jan 1, 2014

By S. V. Petrov

In recent years, heap leaching of gold is becoming wide spread due to low capital and operational costs that allows economically feasible processing of low-grade and cut-off grade ores. Currently, over 30 heap leach projects are operated in Russia. Some of the deposits treated by heap leach methods are almost depleted. Therefore, they will soon require spent heaps detoxification and reclamation. Traditionally, spent heaps are detoxified by chemical treatment. This process is characterized by relatively high kinetics and requires expensive reagents and additional equipment. The main disadvantage of this process is secondary contamination of the solutions by products of detoxification reactions and impurities contained in reagents. If there is enough time, spent heaps can be detoxified by natural degradation. The advantages of the proposed method are low operational costs due to use of existing heap leaching facilities and eliminating the need for chemicals for spent heaps detoxification. Residual concentrations of cyanides and thyocyanates in liquid phase (wet ore) of spent gold ore heaps after detoxification were 0.2~0.3 mg/L. Heavy metals were almost completely removed. The method was successfully used for detoxification of spent heaps at two gold mines.

Jan 1, 2014

By M. L. Wu

A moderately thermophilic acidophiles strain had been isolated from the bio-heap leaching plant in Zijinshan Copper Mine, and the identification based on the PCR-16S rRNA gene sequence homology analysis with morphologic and physiologic methods was conducted by polyphasic taxono-my and phylogeny research. The results show that the strain by depurated belongs to Acidthiobacillus genus and is considered as Acidthiobacillus albertensis.

Jan 1, 2014

By A. M. Muhamedilova, S. M. Narbekova, L. V. Semushkina, D. K. Turysbekov, N. K. Tussupbayev

The research and development of new, more selective collectors in order to improve flotation efficiency represent one of the main priorities in the development of innovative technologies pertaining to flotation separation of various substances and minerals. The use of collectors’ mixtures is considered as the universal instrument for ensuring necessary proportion of chemically and physically sorbed collecting reagents in every individual case. Currently hard-dressed, refractory ores and man-made raw materials, which are characterized by low content of valuable components, fine dissemination of mineral assemblages and similar technological properties of constituent minerals, are widely involved in the recycling processes. The possibility of processing tailings, which are left after flotation beneficiation, has been considered in the case study of tailings of the Zhezkazgan beneficiation plant and the Tishinsk copper ore deposit with utilization of the modified multifunctional flotation reagents. Modified poly-functional collector is the mixture of composite Aerofloat, TC-1000 and butyl xanthate. Reactants ratio is 1:1:3. The advantage of the suggested flotation reagents is that they are composed of two polar groups and have a long hydrocarbon radical. This structure, being in the water during flotation process, plays a dual role: first, as a collector adsorbing on the mineral surface it produces metal complexes with polar groups in the form of bridges; second, apolar radicals flocculate valuable slimed components, thereby intensifying flotation process. It has been shown that flotation of Zhezkazgan tailings with utilization of the lesser modified reagent amount compared to butyl xanthate has enabled to produce crude copper concentrate with 13.0 % copper grade and 80.22 %recovery. Compared to the baseline technology, copper content of crude concentrate has been increased by 5.1 % and the recovery by 31.4 %. It is shown that tailings flotation of the Tishinsky field by applying modified collector allows for increase of the of useful components extraction in a collective concentrate with: copper 9.63 %, lead for 8.41%, zinc 9.2 %, iron 2.73 %, gold 3.57 %.

Jan 1, 2018

By J. Y. Xu

A mutant of Phanerochaete chrysosporium, which is capable of degrading lignin, was bred by ul-traviolet ray irradiation and this mutant strain shows high capability of degrading of lignite. The degradation ratio of original Yima lignite and nitric acid treated Yima lignite by this mutant are 37.6% and 51.62%respectively, whereas those by the original strain are 31.84% and 32.55% respectively. XRD and FTIR analyses of the lignite converted product show that its polymerization degree and average molecular weight are both greatly reduced. The content of the functional groups is also been altered.

Jan 1, 2014

Datun Concentrator currently processes complex sulfide ores in Gejiu Municipality, Yunnan Province, China. The ore contains much higher arsenic than other ores. The run of mine ore is fed to the concentrator to recover copper and tin by bulk flotation and gravity concentration, and then the other sulphides, such as pyrite, arsenopyrite, etc. didn?t get utilized and are discarded as tailings due to the high arsenic content. In order to utilize the pyrites in the tailings, a series of tests have been conducted for finding the solution of arsenic removal from high arsenic-bearing pyrite concentrates through simple flotation process. By means of orthogonal experimental design, the optimized levels and main factors have been found out for the roughing stage. Through selection of the effective in-organic depressants for the arsenic-bearing minerals, the arsenic in the pyrite concentrate can be removed to meet the requirement of sulfuric acid plant (As%=0.5%) by the open flotation process, i.e., one-time roughing and two-time cleaning.

Jan 1, 2014

By K. Saberyan

In this study the extraction of zirconium and hafnium has been investigated by solvent extraction using Cyanex 302 in various media such as nitric, sulfuric and hydrochloric acid has been investigated. Effect of various parameters such as type and acid concentration, extractant concentration, type of diluent, equilibrium time, various foreign ions and finally type and concentration of strip-ping agent have been studied. The results showed that nitric acid was optimum media for extraction of zirconium and hafnium. The extraction of zirconium and hafnium occurred quantitatively in the concentration of higher than 4 M nitric acid but in hydrochloric acid media, quantitative extraction obtains over 8 M HCl. In sulfuric acid media, extraction of zirconium and hafnium is negligible. Stripping studies showed that the optimum reagent for stripping was 0.5M sulfuric acid.

Jan 1, 2014

By J. Y. P. Leite

In a small-scale mining in Brazil?s northeast, scheelite were exploited since 1940?s using a traditional gravity concentration flowchart (composed by jigs and shacking tables) that operates with low efficient for fine particles. Tailing of this plant was submitted to chemical, mineralogical and size characterization. Results pointed 50% smaller than 74µm with a grade of 0.11% WO3. The particle?s size is an important operational variable to heighten recuperation by shacking tables. Tests using Falcon SB40 centrifuge concentrators and shacking table were realized, optimizing their operational variables. Based on the tests results a new flowchart was proposed for concentrating and tailings recovery.

Sep 1, 2012

By J. Leite

In a small-scale mining in Brazil?s northeast, scheelite were exploited since 1940?s using a traditional gravity concentration flowchart (composed by jigs and shacking tables) that operates with low efficient for fine particles. Tailing of this plant was submitted to chemical, mineralogical and size characterization. Results pointed 50% smaller than 74µm with a grade of 0.11% WO3. The particle?s size is an important operational variable to heighten recuperation by shacking tables. Tests using Falcon SB40 centrifuge concentrators and shacking table were realized, optimizing their operational variables. Based on the tests results a new flowchart was proposed for concentrating and tailings recovery.

Sep 1, 2012

By M. Bhartia

India is the 5th largest producer of steel in the world and is slated to produce more than 180 Mt by 2020. Expectedly about 50 % of this would be through the Blast furnace route and the rest through Sponge iron / DRI route. Considering that there will not be any major change in iron making technology by that time, the Blast operation would require lump ore (10-40mm) with around 64% Fe grade and sinter fines (<10mm) with 60% Fe (min) as its feed. DRI process would need calibrated ore of size 5-18 mm as the most suitable size of feed. It is also expected that of the total requirement of ore for the DRI route a significant part would be DRI pellets. In India, there is considerable debate going on regarding the technology to be adopted for the processing of iron ore and there is a lack of clear consensus. The above scenario indicates that the processing requirement of iron ore in the country would involve both washing technology as well as beneficiation technology. CDE Asia Ltd is in the forefront of iron ore processing in the country and the experience gained by the company over the last few years of functioning has led the company to believe that route to be adopted depends on the end product requirement and the starting grade of the feed. Keeping in mind the nature of the feed required for the Blast furnace & DRI operation; it is obvious that good washing technology would be highly beneficial to the iron ore industry. Depending on the grade of ore available the limits of washing will be decided and equipment for lump ore beneficiation such as jigs could be incorporated into the washing circuit. Scrubbing of ore either before washing or selectively scrubbing the lumps could be necessary. Very low grade ore and jig rejects would be required to be totally ground and beneficiated for the production of pellet feed in order to utilize the iron ore resources entirely. Another source of ore for pelletisation would be slimes generated from the washing process as well as the huge quantities already available in the tailings dams in the operating mines. Deslimimg and magnetic route of beneficiation could release at 30-40% of the Fe locked up in these tailings ponds/dams. The paper describes the concept with examples from operating plants and proposes how the adoption could be engineered through test work and proper plan of integration. Keywords: washing, beneficiation, iron ore, lumps, sinter fines, pellets, jigs, screens, evowash, nanowash, thickeners, log washers, drum scrubbers

Sep 1, 2012

By E. V. Manlapig, M. C. Harris

"The complexity of the flotation process has made the identification of an appropriate model structure for the predictive simulation of flotation circuits far from obvious. Work performed under the auspices of the AMIRA P9 flotation program has indicated that the metallurgical performance achieved from a flotation cell arises from the interaction of two essentially independent property classes, namely the cell operating conditions and the properties of the cell feed stream. These observations have led to the development of a model structure that associates a constant set of flotation parameters to the streams of the circuit, which are transformed into a flotation response depending on the operating conditions within the flotation cell.A variety of alternative model structures exist within the literature which do not make this distinction between cell and stream flotation properties, and many of these models are in widespread use for flotation optimisation and design studies, both in industry and academia.In this paper, circuit survey and laboratory batch flotation data collected from an industrial flotation circuit are analysed. The data demonstrate that streams in an industrial flotation circuit exhibit varying particle floatability – concentrate streams typically float faster than tailing streams (Figure 1(a)). This floatability, however, is generally conserved around the various units within the flotation process (i.e. the effective floatability of the combined feed and product streams of a unit is equivalent (Figure 1(b)))."

Jan 1, 2003

By Ivan Bonchev, Elisaveta Djurova, Evgeni Visariev, Viktor Stoilov

"Two types of slag cooling is used world wide - cooling in ladles and cooling in pits. The flotation comparison of the type cooling regimes was done at Aurubis Bulgaria. In Copper smelter Aurubis Bulgaria (Pirdop), the residual copper in the slags from Flash furnace and Converters is recovered by flotation. The slag flotation plant processes blend of three parts FSF and one part converter slag. The slag processing comprises: pit cooling, crushing, two stages grinding (autogenous and ball) and flotation. The copper content in flotation concentrate is over 20 % and in flotation tail is under 0.5 %. In order to improve the copper recovery, different cooling rate of the liquid slags should be achieved. Three cooling experiments with flash smelting furnace (FSF) slag have been done: two of them in pits with different volume and one cooling experiment in metallic ladle. The ambient air temperature during the cooling tests was from -4 to +4 OC. Laboratory flotation tests in open cycle were done with an aim to compare the slags behaviors cooled at different conditions. In this paper the effect of different cooling on the flotation process will be presented. The copper recovery and distribution by sizes in the tails, copper content in the rougher concentrate, and the concentrate yield are discussed."

Jan 1, 2014

By Nóra Schreithofer, Kari Heiskanen

"INTRODUCTIONThe knowledge of the adhesion forces between particles and bubbles is of key importance in the improvement of flotation models. The development of the Colloidal Interaction Force Measurement Apparatus (CIFMA) opened the possibility to quantify the adhesion forces between particles and bubbles. The aim of this study was to examine the effect of three main variables: the approach velocity, the loading force and the loading time on the adhesion force between an air bubble and a hydrophobized silica particle."

Jan 1, 2003

By P. Huang

Chitosan was tested as a depressant in the differential flotation separation of chalcopyrite and galena. The micro-flotation results showed that chitosan selectively depressed chalcopyrite while galena was floated by potassium ethyl xanthate in acidic solutions. With the addition of 0.67 mg/L chitosan (CT) in the slurry of chalcopyrite-galena mixtures at pH 4, the recovery of galena was 95% while that of chalcopyrite was 30%, indicating that chitosan could potentially be used in differential Cu-Pb sulfide separation. Furthermore, the study of chitosan with either low (LCT) or high molecular weight (HCT) in the differential flotation indicated that better separation was achieved by the chitosan with lower molecular weight (LCT). ToF-SIMS was employed to study the distribution of CT on the surface of chalcopyrite-galena mixtures by ion mass spectra analysis and surface imaging, which showed that CT adsorbed heavily on chalcopyrite but barely adsorbed on galena. The positive ion ToF-SIMS spectra provided information on the surface composition of chalcopyrite-galena mixtures after CT treatment. It appears that the selective adsorption of CT on chalcopyrite was originated from the strong interaction between NH3+ and Cu. Keywords: differential flotation, micro-flotation

Sep 1, 2012