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By Teemu Väyrynen, Matti Vilkko, Antti Jaatinen, Pekka Itävuo

"This paper shows that smooth and accurate feed-hopper level control is essential for consistent cone crusher operation. The objective of the paper is to define the best practices for tight control of cone crusher feed-hopper level. The paper discusses the challenges involved in a delay-dominant level control problem (specifically, dead-time-induced performance and stability issues, mass flow disturbances, process and actuator non-linearity) and proposes five corresponding control structures. The performance of the proposed control structure candidates is evaluated in a simulation study and, finally, a full-scale experiment is conducted for the best-performing candidate. The results of this study emphasize the importance of control structure selection. While the most obvious control structures failed to deliver the desired performance, the best result was achieved by using control structures that eliminate the conveyor transport delay (dead-time) from the control loop. In practice, the control loop dead-time can be eliminated by either using an actuator (variable-speed feed conveyor) that is connected directly to the feed-hopper, or by redefining the process boundaries closer to the used actuator (regulate the circuit mass balance instead of feed-hopper level). The presented control structures provide means to achieve a consistent cone crusher performance and size reduction. This facilitates efforts to improve the plant’s performance and increases the plant’s overall stability."

Jan 1, 2014

By Vasile Murariu, William Pate, John Herbst, Dilek Alkac

"Multiphysics models are essentially first principles models capable of providing very accurate micro scale predictions. The computational requirements for Multiphysics Models are extensive, precluding their direct use for flowsheet simulations. Population balance models get their form from theory but the model parameters have to be provided from experiments. The prediction errors for the population balance models are typically significantly higher than those for the Multiphysics Models but the computational effort for Population Balance Models is typically much less than that for the Multiphysics models. The hybrid model described here takes advantage of the strengths of each of the two primary model types and minimizing the weaknesses of each. The Multiphysics Model is used to perform high accuracy "experiments" that are difficult or impossible to conduct in laboratories or plants. The results of these experiments are combined with standard laboratory or plant data to parameterize and further enhance the Population Balance portion of the hybrid model. The creation of a useful Hybrid Model is demonstrated for a MP1000 secondary crusher. The validation of the hybrid crusher model is also presented. Finally the use of the Hybrid Model is illustrated in a full comminution flowsheet simulator."

Jan 1, 2014

By Shi Shuaixing Zhang Yuejun, Fan Xuesai Zhangming

"For the traditional principle of flotation cell design, or in the perspective of some researchers, the mixing effect of impeller for flotation cell is not only to suspend the particles off the bottom, but also to mix slurry well to achieve a uniform system. But for some special processing conditions, the depth profile of slurry concentration and particle size demonstrates an obvious difference. In the part around of the impeller in the cell, the slurry concentration is much higher than the part below the lip.For the vanadium titano-magnetite flotation process, distinguished with high concentration and large coarse particle size fraction, even though the concentration is very high, it can reach good gas dispersion, which is a fundamental principle for flotation cell design and application. The gas dispersion is not a challenge in the high slurry concentration environment, not only in the vertical direction, but in the cross section. Different levels (the distance from the lip is 400mm, 700mm, 1200mm, 1700mm, 2200mm, 2700mm) slurry in the flotation cell is sampled and analyzed. The slurry concentration of the 3 levels(1700mm, 2200mm, 2700mm) is about 55%, but the slurry concentration decreases from 55% to 25% sharply towards the lip.Therefore, a new understanding and viewpoint is presented, that the uniform system of slurry is not always reasonable for all of the flotation process. For some special process, if the coarse particles are needed to agitated well and transported to the upper cell, the quiescent zone in the upper cell will be destroyed and enhance the detachment probability for the coarse particles. The difference of slurry concentration and particle size fraction benefits the air dispersion and coarse mineral particles recovery.1.INTRODUCTIONNowadays, flotation is the most widely used separation process in the mineral processing industry. The importance of flotation technology in the global economy is significant. A rough estimate of the quantity of crushed ore treated by flotation is about nine billion tons per year, and the portion of base metals processed using this method is approximately 95% (Brewis, 1996)."

Jan 1, 2018

Incomplete liberation of mineral particles is one of the key factors limiting the performance of industrial flotation circuits. This work aims to quantify the relationship between different breakage modes and how these affect mineral liberation properties. A copper porphyry (bornite) ore sample was subjected to breakage using a piston-die compression unit and an impact mill. The particles produced as a result of each mode of breakage were then characterised using Mineral Liberation Analysis (MLA) to quantify the mineralogical and liberation properties of the progeny particles. The impact mill was found to produce bornite that was finer grained relative to the host particles. In con-trast, bornite discharged from the piston-die unit closely followed the size distribution of the host particles and was retained to a greater extent in the larger/intermediate size fractions. The results provide insight into what breakage methods are optimal for the purposes of downstream separation.

Jan 1, 2014

By V. A. Ignatkina, V. A. Bocharov, T. I. Yushina, I. M. Petrov, A. A. Kayumov

"The purpose of this research was aimed at increasing recovery of metals from rebellious sulfide polymetallic ores of nonferrous and rare metal deposits. The ores under consideration have common processing features, including textural and structural complex characteristics, irregularity of impregnation and wide range of grain size, up to nanoparticle size, variable complex mineral composition, low content of precious metals etc. This all predetermines the need for advanced processing schemes with deep selective liberation and separation of minerals with intercycle release into rough concentrate and fractional products with the use of multi-stage cycles of individual dressing, based on an optimum combination of various integrated beneficiation and hydrometallurgical processes. The application of existing standard processes does not enable the production of high-grade selective concentrates without reducing the recovery rate due to incomplete separation of fine mineral intergrowths and overgrinding of brittle ore and rock minerals.The combined beneficiation processes for such type of resources, aimed at increasing recovery of nonferrous, rare, and precious metals are based on flotation methods in combination with gravity concentration to produce rich rough collective or selective concentrates, comprising readily floatable mineral fractions. At the same time, hardly recoverable and non-separable mineral associations are released into separate concentrated products for following dressing by individual processes. The proposed combined process provides for successive selective liberation of minerals with release of rich readily recoverable mineral fractions at the preparation and ore beneficiation stages. The hardly recoverable mineral associations shall be released in subsequent operations with the use of dressing, based on a combination of beneficiation and pyro- and hydrometallurgical methods."

Jan 1, 2018

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 Janne Kauppi, Kaj Jansson, Piia Suvio, Saara Hagnäs

"Historically the focus at the mineral processing sites has been to improve the production operations, while little focus has been set on how factors, such as the quality of water used in the process affects the metal recovery. Simultaneously increasing public pressure and water scarcity is driving the mining industry to recycle more water back to the process, which in turn leads to accumulation of impurities within the recycled water. This paper presents a concept for a systematic approach on targeting the impurities that have a negative effect on the metal recovery at the flotation circuit by using a novel solution called Process Water Recycling Plant (PWRP). These plants are designed with specific ore type in mind. PWRP produces cost-effectively process water to different target qualities, especially for flotation purposes enabling higher and more stable flotation recovery. It consists of pre-designed and standard water treatment units for a wide range of volumes. The application-specific configuration of units is governed by the water quality requirements, and can be designed according to specific customer needs. Testing has been carried out in order to investigate, which recycling water impurities affect the different ore types and how the metal recovery in flotation is affected as a consequence of the poor-quality water. The results indicate that every ore type is impacted differently and without a good understanding on how the water quality impacts the process performance, adverse effects on the flotation recovery can occur.INTRODUCTION With a focus on where water is used within the mineral processing, it has become evident that even though water is used in several different processes, majority of the water losses within the site occur at the tailings processing and the tailings storage facility. New tailings management technologies that can increase the recovery of water are actively being developed, but the key to improving the efficiency of water use and reducing the operational risks lies in closing the water loops and increasing the slurry density in the tailings processing. With this shift from conventional tailings technologies towards paste and dry stacking, water efficiency is vastly improved, but it might in turn lead to process water challenges with impurities, reagents and fines being recycled and accumulated within the production processes."

Jan 1, 2018

By R. Prakash

Column flotation has now gained wide application in the recovery of various minerals. The performance of the flotation device depends on the mixing characteristics of the phases inside the devices. In this work, quality of mixing in a flotation column has been analyzed by using information entropy theory. Empirical models have been developed for flotation column with the parameters which affect the quality of mixing. The efficiency of the particle separation in the flotation column has been enunciated based on the quality of mixing. The present analysis on the quality of mixing in flotation column may give insight into a further understanding and modeling of flotation devices in industrial applications.

Sep 1, 2012

By Caibin Wu, Ali Lei, Ningning Liao, Jingsheng Ye

"The particle size distribution characteristics of ground product can influence the quality of the classification overflow and the next beneficiation indexes in an ore concentrator. Usually, the size distribution of ground product is considered to be determined by that of new ball mill feed. However, based on large amounts of data from industrial grinding circuit surveys, this paper has clearly shown that the size distribution of ground product should be determined by the size characteristics from classification underflow unless the circulating load was small, because the new feed is an important component and occupy a dominant position of mixed ore from belt feed and classification underflow. On the other hand, the correlation coefficient of the size distribution between ground product and classification underflow can be more than 0.99 when the relevance principle and its method are used. Meanwhile, their P80 value also keeps a synchronous correlation. The greater the capacity of classification underflow is, the higher the correlation of size distribution between the ground product and the mixed feed is. Furthermore, the correlation coefficient of the size distribution between ground product and classification overflow which is from primary or secondary can be 0.96. It is another discovery that the correlation coefficient is related to the type of classifier. The coefficient of size distribution of overflow and underflow from hydrocyclone is superior to that of spiral classifier, which can explain the reason why the hydrocyclone is widely used to replace the spiral classifier in concentrator.INTRODUCTION It is well knows that ball mill circuits closed with cyclones or spiral classifier such as a primary grinding circuit, a secondary grinding circuit and SAB mill have become an industry standard. Which grinding process employed will be determined by the P80 value of ground products. When the primary closed circuit ball mill or SAB that it is different throughout between the two processes was employed, a grinding fineness with -200mesh under 68% will be available. However, the secondary grinding circuit with the fineness of -200mesh above 80% can be conducted. Of course, the grinding fineness is determined by the grain size characteristics of the mineral."

Jan 1, 2018

By Dingwu Feng, Jannie S. J. van Devente

"The effect of ultrasonication on reactions at solid/liquid interfaces was investigated in two slurry systems, i.e. gold cyanidation and geopolymerisation. The kinetics of gold extraction were significantly enhanced and the cyanide consumption was reduced in the cyanidation of a pyrite concentrate using ultrasonication, probably due to the prevention of leaching passivation, the improvement of the dissolution of the gold host sulphides and the oxidation of soluble sulphides to sulphate. The effectiveness for ultrasonication was improved with the injection of oxygen and the addition of dithiophosphate through enhancing the formation of the oxidation radicals and selectively inducing cavitation bubbles directly at the sulphide interfaces. Ultrasonically enhanced cyanidation could render currently uneconomic deposits viable for extraction by improved cavitation efficiency with the aid of surfactants.Ultrasonication increased the compressive strength of the formed geopolymers through accelerating the dissolution of the Al-Si materials, strengthening the bonds at the solid particle/gel phase interfaces, enhancing the polycondensation process and improving the formation of semi-crystalline to crystalline phases. The use of power ultrasound will yield high-performance geopolymer materials."

Jan 1, 2003

By Héctor X. Toro, José Francisco Cabello, Douglas Batista, Álvaro Videla, Claudio Luiz Schneider

The Minas-Rio Project, located in the state of Minas Gerais, Brazil, is currently under construction. The new plant will have a regrinding circuit that uses VertimillTM. The objective is to process itabirite iron ores and it is expected that the consumption of media will represent a large part of the plant operating cost. Many studies in the literature indicate that the size of the grinding media directly influences the grinding efficiency. The size distribution of the charge media is related to the surface area of the charge. In this study, a sample of itabirite iron ore was tested with respect to grindability in a laboratory scale ball mill. The test mill was equipped with a torque device to accurately measure power consumption, as required for the determination of energy specific kinetic parameters. Five tests were carried out with different sizes of steel balls and with SICAM (sub-inch Cast Media). The size distributions of the feed and product of the several grinding tests were used to calibrate population balance model parameters for each condition. The results confirmed that the ball charge with smaller diameter is the most efficient among the different media charge tested.

Jan 1, 2014

By C. Tokoro

Co-precipitation of dilute toxic anions with ferrihydrite is an important removal mechanism in wastewater treatment system. Although, numerous qualitative studies have been published on removal characteristic from wastewater of dilute anions by co-precipitation treatment, detail mechanism or quantitative characteristic is not well understood. This paper discussed the co-precipitation mechanism of As(V) and Cr(VI) with ferrihydrite by comparative experiments between co-precipitation and simple adsorption. In this study, co-precipitation experiments and simple adsorption ones were distinguished closely. In the former, precipitation of hydroxides and adsorption of anions develop simultaneously, but in the latter, anions adsorb onto prepared hydroxides. Although high affinity anions for hydroxides (e.g. As(V) for ferrihydrite) showed quantitative difference of removal ratio between co-precipitation experiments and simple adsorption ones, low affinity anions (e.g. Cr(VI) for ferrihydrite) showed quantitative agreement in spite of deferent forms of ferrihydrites between them, that is, amorphous ferrihydrite was formed in co-precipitation experiments, but goethite was formed in simple adsorption ones. In order to discuss the mechanism of co-precipitation phenomena, three experimental studies have been carried out: (i) adsorption isotherm measurement in the co-precipitation experiments of As(V) or Cr(VI) with ferrihydrite, (ii) zeta potential measurement of co-precipitated or simple ad-sorbed ferrihydrite with As(V) or Cr(VI), and (iii) XRD analysis of co-precipitated As(V) for ferrihydrite. All experimental results suggested the main mechanism in co-precipitation phenomena of As(V) was not only a surface complexation (simple adsorption) but also a surface precipitation.

Jan 1, 2014

By Tamara F. Kondrateva, Evgenia E. Savari, Galina V. Sedelnikova, Rauf Y. Aslanukov, RAS (INMI), Grigori I. Karavaiko

"The investigation is dedicated to study of biohydrometallurgical processing of refractory gold-arsenic concentrate with the large content of pyrrhotite. Sulfide concentrate of chemical constituents: 75g/t Au, 4,7g/t Ag, 6,3% As, 29,3% S, 2,3% Sb, 0,5% ? (organic) and of mineral composition, %: 11,8 arsenopyrite, 39 pyrrhotite, 12 pyrite, 2,9 antimonite and the rest – aluminosilicates, carbonates and quartz, was studied. The recovery of gold from concentrate by cyanidation is 51,2%. The rest of gold is embedded as finegraded segregation in sulfides.Sulfide oxidation process study is described. Bacterial oxidation was executed on a pilot laboratory unit using combined autotrophic bacterium: A. thiooxidans , A. ferrooxidans, Leptospirillum ferrooxidans and sulfobacillus thermosulfidooxidation, pH=1,5-2,2, t=28-32?C, oxidation time 120 hours. Pyrrhotite is the least stable sulfide mineral with electrode potential 0,45V versus arsenopyrite (0,55 V) and pyrite (0,55-0,6 V) and is oxidated primarily. Pyrrhotite oxidation is followed by large amount of elemental sulphur, which has a bad influence on cyanidation.It’s established that the rate of arsenopyrite (for the first 48 hours) from concentrate containing 39% pyrrhotite is 2-3 times as less as the rate of arsenopyrite bio-oxidation from concentrate without pyrrhotite. The arsenopyrite bio-oxidation is accelerated only after the elemental sulfur was oxidized by bacterium A. thiooxidans and elemental sulfur percentage was reduced from 6,8 to 3,9%. The bacterium concentration is increased from 2,5x107 to 2,5x109 cells/ml. Almost full oxidation of arsenopyrite (98%) and pyrrhotite (98- 99%) is finished in 120 hours. We have studied two pretreatment methods for elimination sulfur content influence on cyanidation: aeration in lime and electrochemical treatment. Such an operation enables to have supplemental oxidation of elemental sulfur and other oxygen and cyanide absorbants before cyanidation. After treatment the content of elemental sulfur was decreased from 3,9 to 2,2%, gold recovery from 90 to 96% and cyanide consumption from 16,2 to 7,2 kg/t decreases. The content of toxical rhodonite-ions in liquid phase of pulp and disinfection reagents consumption were decreased as result of elemental sulfur content in bio-oxidated product reduction."

Jan 1, 2003

By Mohsen Hashemzadehfini

Nowadays heap leaching has become established as a mineral processing technology for treatment of some low grade minerals such as copper, gold, and zinc, etc. Heap height, particle size, leach reagent consumption, and metal recovery are four important metallurgical parameters in a hydrometallurgical process like heap leaching. This paper investigated the effects of heap height and particle size on copper recovery as well as acid consumption. Three heap heights of 2, 4 and 6 meters and two particle size fractions of less than 25.4 mm and 50.8 mm were selected as variables in the experiments. The research results showed the inverse relation between heap height and copper recovery as well as acid consumption. Under given conditions, the copper recoveries of minus 25.4 mm ore are 78.63%, 66.27% and 52.88% higher than that of minus 50.8 mm samples for the heap heights of 2, 4, and 6 m, respectively. Both copper recovery and acid consumption increase with decreasing particle size. Keywords: heap leaching, heap height, particle size, acid consumption

Sep 1, 2012

By Lutz Rolf, Halit Z. Kuyumcu, Salas Cazón. Milton A.

Aim of experimental investigations was the mathematical description of the abrasion process running with a single particle stress. This is on the one hand the basis for the physical interpretation of the process, on the other hand the base for the simulation of abrasion processes carried out in technical scale. With this investigation for the first time the influence of the particle shape changing with increasing abrasion progress was quantitatively described. This influence affects itself particularly strongly on break-fresh particles up to an abrasion degree of approximately 10 to 20%. This is for the description of technical processes the most interesting area.

Jan 1, 2003

The value creation with kaolin clays depends on removing the colored impurities which manifests in to higher brightnessone of the most sought after properties on applications such as paper coating, paint and others. The processes for removing impurities include magnetic separation, froth flotation and selective flocculation. While the flotation and selective flocculation processes exploit the physico-chemical differences between the surface properties, the magnetic separation uses the bulk magnetic susceptibility differences between the diamagnetic clay and ferro- and para-magnetic nature of the impurities. The major advantage with magnetic separation remains high yield and no or low reagent usage. However, the magnetic separation technology suffers from low separation efficacy when finer colored impurities (<1 µm) are encountered in the feed. Use of stronger magnetic intensities during magnetic separation showed limited success; nonetheless the adverse effect due to finer size range remains a dominant effect even at 5 Tesla magnetic field. Furthermore, the presence of diamagnetic colored impurities irrespective of their sizes can not be removed. Cytec Industries has recently developed a ?bolt-on? chemical enhancement technology for magnetic separation that essentially embraces the best product performance attributes of flotation and selective flocculation while keeping the chemical usage to a minimum level and using the readily available magnetic separation equipment. The paper will outline the technology and illustrate optimization work at pilot plant magnet on a wide variety of crude accommodating the process needs and plant limitations. The major advantages of chemical enhancement technology to magnetic separation include: 1) simple extension to existing magnetic separation technology, 2) ability to produce comparable product in quality with cost effectiveness compared to flotation and selective flocculation, 3) removal of impurity minerals over wide size range, 4) removing non-magnetic impurities, 5) providing robust process with high process yield and 6) operation-friendly nature. Furthermore, chemical enhancement technology for magnetic separation has also emerged as a platform for re-moving impurities at low levels in other mineral systems as well.

Jan 1, 2014

By Ricardo Montero

At this time, over 300 tons of Au are used in electronic equipment each year with other precious and strategic metals such as Ag, Pt, Pd, Cu, Nb, Ta, etc. After the use-phase, the electronic devices become electronic waste (e-waste); consequently it is important to consider e-waste as a secondary supply for recovery of these metals. One of the most important components is the printed circuit boards (PCBs) because the amount of their precious metals is ten times higher than rich precious metals bearing ore. This paper presents the recovery of Au, Ag, Cu and Nb from PCBs of discarded computers using leaching column technique. The amount of these metals in used PCBs was: 613 g/ton of Au, 1515 g/ton of Ag, 36 g/ton of Nb and 23.4 % of Cu. The PCBs were crushed with a hammer mill until reaching a particle size between 3.33 mm to 0.43 mm. Then, it was leached with sodium cyanide solution in a glass column using the following conditions: sodium cyanide concentration 4 g/L, flux 20 L/kg PCBs day, pH between 10.5 to 11 and leaching time 15 days. Every day, after leaching, the pregnant solutions passed through a column with activated carbon to complete the closed loop system. The following recoveries were obtained: 46.6% of Au, 51.3% of Ag, 47.2% of Nb and 62.3 % of Cu. The products obtained are: a) loaded carbon that contains the desired metals and b) processed PCBs with precious metal contents. A preliminary technical-economic study shows the feasibility to create a small-scale PCBs recycling plant. The initial investment is on the order of US$ 155 639, considering the recovered metals from loaded carbon. The internal rate of return for 10 years period (IRR) and net present value (NPV) estimated are 27% and US$ 105 926 respectively. Keywords: printed circuit boards, recovery, precious metals, niobium, leaching column

Sep 1, 2012

By Antony Amberg, Gonzalo Saldías, Romke Kuyvenhoven, Catherine Souza, Heriban Soto, Francisco Soto

"Vizcachitas is an advanced stage copper–molybdenum porphyry deposit, fully owned by Los Andes Copper and located in Central Chile. The property contains an indicated resource of 1,038 million tonnes grading 0.37% Cu and 0.012% Mo, and an inferred resource of 318 million tonnes grading 0.345% Cu and 0.013% Mo (Coffey & Alquimia, 2014). The deposit occurs in the same geological belt as several other giant copper-molybdenum porphyry deposits including Río Blanco-Los Bronces, Los Pelambres-Pachon and El Teniente. In 2018, the original Preliminary Economic Assessment (PEA) study from 2014 was updated; this paper presents the geometallurgical testwork that was performed to support that update. The testwork focused on the metallurgical characterization of 40 DDH samples and the development of a more profound orebody knowledge by relating geological features with metallurgical performance. The scope of work included complete chemical and mineralogical QemSCAN characterization; SAG, ball mill and abrasion testing; complete rougher and cleaner kinetics including locked-cycle-test; environmental ABA and settling tests on rougher tailings. The results show that the ore can be classified as medium-hard, with a hardness that is slightly below the average for large Cu/Mo deposits in the region. A good correlation was found between lithology and breakage characteristics, implying that the specific energy consumption (kWh/t) is well correlated to rock type. The results of the flotation tests were very encouraging and did not show significant variability. An overall Cu recovery of 91% can be expected for the flotation circuit. The use of a relatively coarse primary grind size gave good final recovery and grade for both Cu and Mo, and deserves further attention in future work, as this impacts positively both energy consumption and water recovery.INTRODUCTION Los Andes Copper Ltd. is a Canadian exploration and development company focused on the acquisition, exploration and development of advanced stage copper deposits in Latin America. The company owns 100% of the Vizcachitas project in Chile, the largest copper deposit in the Americas not controlled by the majors. Vizcachitas is a copper-molybdenum porphyry deposit, located 120 km north of Santiago, in an area of very good infrastructure."

Jan 1, 2018

By G. V. Kalabin

"The paper supports applicability of satellite imagery at regional and local level for rapid quantitative assessment of natural environment in zones of activity of mining complex enterprises. Exacerbation of environmental problems during mineral mining and processing associated with their scale and geography of field distribution through the vast territory of our country requires constant monitoring of natural environment status, which necessitates engagement of space surveillance nowadays. It is proposed to use the monitoring of land cover and land use at regional and local level for the environmental assessment of a particular production or complex productions. You must establish the dependence of NDVI change trend with the magnitude of anthropogenic impact on the source or multiple sources of environmental pollution a particular area.. We present the results of studies of vegetation remote sensing methods in a number of territories placing mining enterprises. INTRODUCTION Ensuring a healthy environment is necessary both in untouched areas and disturbed. The condition of the developed territories should be monitored with particular attention, since the restoration of the disturbed territories requires great efforts and financial costs. More narrowly, the health of the environment (Zakharov V.M. and etc.,2001) means its quality ensuring the health of man and other species of living organisms, which includes two aspects (Zakharov V.M. and etc, 2000): - ensuring an environment conducive to human health as a biological species: - maintaining the health of the natural environment, i.e. its constituent species of living organisms and plants. The consequence is the disturbance of natural ecosystems, which determines the quality of the environment, favorable for human habitation and the state of health of the population in total determine the status of the territories where enterprises for the development of georesources are located and allow them to be ranked according to the degree of environmental danger. Without knowledge of the trajectory of ecosystem successions, it is impossible to offer adequate requirements for the technologies used to ensure the implementation of the preserved natural potential after the removal or reduction of man-made stress."

Jan 1, 2018

By Jia Ma, Lu-De Qiang, Zhi-Chao Liu, Chun-Feng Li, Guang Li, Bao-Bin Tang

"At present, research on the surface chemical properties of uranium minerals is very scanty, which restricts the research progress of uranium ore flotation process research. The research aimed at exploring the surface characteristics of two common uranium minerals and providing basis for flotation process to enrich uranium minerals in ore. This paper selected pitchblende and uraninite as the object of study, which are widely distributed in uranium deposits. We chose out the pure minerals of pitchblende and uraninite from different ores collected from different uranium deposits. By means of Zeta potential test and X-ray photoelectron spectroscopy (XPS) test, a preliminary study on surface characteristics of the pure minerals of pitchblende and uraninite was conducted. And the significance of the change of Zeta potential, the elements composition and valence state on the minerals surface for flotation was discussed. The research shows that, the Zeta potentials of pitchblende and uraninite in pure water are negative mainly when the pH value varies from 2 to 11, which maybe a result of the difference of ionization capacity between two kinds of oxy-compounds on the surface of minerals. On the surface of pitchblende and uraninite, the metal elements are mainly U, Th and Pb. U is mainly in the form of UO2, Th is mainly in the form of ThO2, and Pb is mainly in the form of Pb and PbO. Based on the surface characteristics of pitchblende and uraninite, we can select process and reagents appropriately in uranium ore flotation.INTRODUCTION Globally, the major challenges associated with exploitation of low grade ores are about finding economically feasible processes for reducing the mass of gangue minerals (Filippov et al., 2012). Among the beneficiation technologies of low grade uranium ores with complex minerals assemblage, flotation is the common process which is used to reduce production cost and eliminate the acid-consuming minerals (Li et al., 2016; Liu et al., 2015)."

Jan 1, 2018