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By Mario Gerards

Maturing populations create an increase in the demand for the type of non-ferrous metals, which are used in the manufacturing of electronic products. The depletion of existing high-grade deposits, make it necessary to boost the efficiency of beneficiation processes and most importantly the yield (recovery rate of the value commodities). Increasing demand now makes it worthwhile to tap into resources, which were previously considered waste, for example secondary deposits such as tailing ponds and electronic waste. In order to achieve increased yields, increasingly finer, or even ultra-fine fractions have to be treated. In most cases, mineral characteristics such as size and density call for non-mechanical, high-capacity technologies to be used. There are various technologies that allow for the separation of fines and ultra-fines. This paper outlines the dynamics and efficiency of pneumatic flotation with emphasis on its application to the recovery of non-ferrous metals, from electronic waste. The conventional agitator flotation technology of an electronic waste processing plant was not able to recover ultra-fine non-ferrous metals satisfactorily, due to losses within the tailings. Because of its adaptability and its inherent suitability for non-ferrous metals, pneumatic flotation has been incorporated to the existing process achieving excellent results. The merit of the process lies in the state of the art technology, which does not utilize compressed air and any rotating parts, which results in a reduction in wear and energy requirement, both features of this innovative technology. In addition, the use of pneumatic flotation resulted in a significant reduction in residence time, when compared to mechanical flotation. Pneumatic technology is able to influence air bubble size in a flotation cell, by changing the speed and pressure of the slurry stream. Higher slurry velocities lead to the formation of smaller air bubbles, which is required for the successful flotation of ultra-fine particles. Conversely, decreasing the slurry velocity leads to bigger air bubbles. The optimum bubble size can be created according to different feed characteristics. This is important in case of feed fluctuations.

Sep 1, 2012

By S. H. Morar

Froth stability is widely recognized as a key driver of flotation selectivity. It is well known that froth stability is affected by the type and quantity of surface active reagents present (frothers), and the concentration and hydrophobicity of solid particles present. While some studies have been performed on the effect of frothers on froth stability in three-phase systems and the hydrophobicity of particles present, very little work has been performed on the effect of solids loading on froth stability. This may be due to insufficiently robust measurement techniques. This paper investigates the use of a new machine vision measurement to measure solids loading, and the relationship between this measurement, bubble size, and bubble burst rate on the froth surface. Keywords: froth flotation, machine vision, solids loading

Sep 1, 2012

By Bianca Foggiatto, Marcos Bueno, Rajiv Chandramohan, Eddie McLean, Greg Lane

"With the increasing depletion of high-grade ore deposits, smarter mineral processing solutions are required to achieve sustainable and economic methods for mining and processing low-grade deposits. In order to make the treatment of low-grade deposits economically viable, large quantities of rock need to be mined and processed. The associated infrastructure costs (power, water supply, accommodation and support services, waste storage) result in a substantial penalty on the project, from both capital and operating cost perspectives. As a consequence, the challenge for the mining industry is to overcome the associated rise in energy and water consumption as well as increased project complexity when processing large amounts of low grade ore. Ore sorting technologies have been used for many years, predominantly on small projects, enabling the upgrade of marginal ores. Several sorting methods based on characteristics including specific gravity, radiometry, colour, particle size, grade and other detectable physical characteristics have been employed. The challenge for large low-grade ore bodies is to crush and sort at coarser rock size in order to minimise specific energy consumption in comminution and to reduce waste disposal costs. For large projects, the understanding of the economic impact of ore sorting is limited. The economic drivers include plant head grade improvement; sorting infrastructure capital, operating and maintenance costs; waste material handling and other environmental costs related to waste disposal. This paper analyses the economic impact of ore sorting in a large mineral processing operation. The focus of the analysis is to compare NPVs for a circuit including screening and ore sorting stages. A project for processing an Australian copper sulphide ore is considered as an example for this study."

Jan 1, 2014

By F. Concha

A robust theory of sedimentation-consolidation evolved and was accepted by researchers world-wide in the last two decades of the 20th century. This theory provides a reliable method of thickener design and simulation. However, a process model, simple or sophisticated, empirical or phenomenological, is useful only if it is possible to determine, in an objective way, its experimental parameters. Research workers at the University of Concepción, together with Cettem Mineral Technology Center, created an integrated system of thickener design, simulation and control, including instrumentation, algorithm and software, which can be used by personnel in industry without specialized knowledge of thickening theory. In the paper, the development of three instruments for the measurement of pulp concentration, solid flux density and sediment compressibility is described. Each instrument uses software for data input, parameter calculation and results display. The paper also describes software for the optimization of the experimental parameter and for the design and simulation of industrial thickeners. Finally, mathematical algorithm and control strategies based on the phenomenological model are presented and compared with classical feedback control.

Jan 1, 2014

During incineration of municipal solid waste (MSW), some heavy metals and other environmentally harmful elements are liberated into bottom ash. The stricter environmental regulations require a higher immobilization efficiency of the ash before its safe disposal and application. Vitrification is one of the promising options, and has the advantages of high destruction efficiency of organics, high immobilization of heavy metals, and large volume reduction. The main components of the vitrified slag are SiO2, CaO, Al2O3, Fe2O3, Na2O and MgO, and the compositions have direct effect on the glass formation during vitrification, and further on the physical and mechanical properties of the slag. To provide essential data for the utilization of bottom ash as vitrified slag, the phase relations and thermodynamic properties of the oxide system need to be systematically investigated. In the present study, the liquidus temperature of the typical vitrified bottom ash slag was determined by using differential scanning calorimetry (DSC) measurement. High temperature equilibrium experiments were conducted to investigate the phase relations of the sub oxide system of CaO-SiO2-Na2O by means of Scanning Electron Microscopy (SEM), Electron Microprobe Analysis (EMPA) and X-ray Diffraction (XRD). The results show that the melting temperature of the vitrified bottom ash is around 930°C. In the CaO-SiO2-Na2O system with less than 50 mol% SiO2, the liquidus temperature de-creases with increasing amounts of Na2O along the tie-line of Na2O-Ca3Si2O7. Two compounds Na2Ca3Si2O8 and Na4Ca8Si5O20 are identified in the oxide system.

Jan 1, 2014

By Klaus M. Hahn, Hermann Wotruba, Bernd G. Friedrich

"Due to an increasing demand for nickel and cobalt and the depletion of nickel sulphide deposits worldwide, the production of ferronickel from lateritic nickel ores becomes more significant. About 60 percent of nickel reserves are present in laterite deposits. Common production methods like acid leaching or smelting operations implicate high material and energy consumption. Physical processing methods are also not efficient, because of the fine microstructural intergrowth of the minerals carrying valuable elements such as nickel and cobalt. Due to the high energy consumption of metallurgical treatment of lateritic nickel ore (nickel grade: 0.8 - 3.0%, Co: 0.05 - 0.15%), the separation of waste material (about 75 - 85%) before the metallurgical treatment is desirable. Therefore, an alternative process has been developed, combining a pyro-metallurgical pre-treatment with selected mechanical processing methods. The developed process consisted of a selective pre-reduction and non-selective segregation of the contained metal phases in the first stage. By this, the properties of the metal carrying minerals were changed and could become subject to concentration by means of fine beneficiation processes afterwards. The parameters of the pre-reduction and segregation were varied and the pre-treated samples were examined concerning their efficiency of metalization grade and metal grain size. This paper describes the investigation of pre-treatment methods of a lateritic nickel ore. The pre-treatment and possible subsequent separation methods were examined with regard to the recovery of the valuable elements. Metalization grade was around 80% for both Ni and Co with metal phase grain sizes below 20 µm. Scanning electron microscopy revealed distribution of new metal phases not only on the reducing agent, but also on the “slag” material.INTRODUCTION Nickel laterites are characterized as strongly weathered regoliths with several zones containing reserves of nickel (Ni) and cobalt (Co). These laterites are formed on serpentinites and ultramafic rocks under climatic and/or tectonic conditions that have changed over time (Butt & Cluzel, 2013). The formation of Ni laterites is influenced by numerous geological and environmental factors. In general, there are three ore types named according to the dominant Ni hosting minerals: oxides, hydrous magnesia (Mg) silicates and clay silicates (Butt & Cluzel, 2013). The most Ni laterite deposits contain two of these ore types, usually an oxide zone and an either clay or Mg silicate zone. Distribution of these principal deposit types, their average Ni-bearing phases and mean Ni grade are shown in Table 1. A schematic profile of the different deposits based on the development on serpentized ultramafic rocks is given in Figure 1 (Butt & Cluzel, 2013)."

Jan 1, 2018

By M. Evertsson, M. Johansson

"In minerals processing control is vital to increasing performance and output of a plant. Model predictive control (MPC) is one of the most effective control strategies used in process industry. Sbárbaro (Sbárbaro and Del Villar, 2010), Asbjörnsson (Asbjörnsson, 2015), and Légaré (Légaré et al., 2016) have for example highlighted the possibility to simulate, develop and tune control systems using plant simulators within minerals processing. In more recent years the use of model predictive controllers have increased, and many process industries now utilize more advanced control methods to regulate their processes, raising the question regarding how to, build, test and verify a proposed control solution successfully. In this research, a linear model predictive controller is formulated and applied to a simulator of an existing tertiary crushing circuit. The circuit has in previous work by Johansson (Johansson, 2017) been modeled in MATLAB Simulink and calibrated relative plant data to an average error of less than 10% over 8 hours of production. The work demonstrates how to formulate the controller model structure to describe conveyor belts, storage components, screens, crushers, and control objectives for a minerals processing circuit. The work illustrates how to apply and successfully evaluate possible upsides in a circuit. The advantage of a crushing circuit simulator is that it can be configured, tuned and modified in any possible way, which is of great benefit to developers and engineers. Additionally, examples of how to use estimated measures to improve the performance of the plant are demonstrated. The control performance is finally evaluated for three different controller configurations."

Jan 1, 2018

Mineral processing is an energy and water intensive activity. Mill comminution equipment usually has high energy requirements which necessitate extensive cooling to remove heat. Cooling requirements are typically 10% to 20% of the comminution energy. If there is an adequate supply of suitable water, open water-based cooling systems are the simplest, cheapest and most energy efficient cooling method available. This paper describes a method to determine the water demand for open water-based cooling systems at a plant and to determine whether the mine has sufficient water to meet that demand.

Jan 1, 2014

By P. K. Fedotov

At projecting mining-concentrating complex at the deposit ?Zapadnoye? (Russia) it was considered to enable an opportunity of refusal from conventional SAG-mills. First time a scheme of gold bearing ore destruction using Roller Press RP 5-100/90 had been developed and integrated. The plant was launched in summer 2003 and presently it has achieved designed technological parameters, processing throughput comes to 1 million tons of the ore per year.

Jan 1, 2014

By G. Bulut

The aim of this study is to produce desiccant clay from a well known Ca-bentonite deposit in Turkey. Towards this aim, bentonite samples were first procured and then subjected to some characterization tests. Various methods were applied to enhance the moisture adsorption capacity of bentonites to a desirable level. These methods include utilization of some additives namely calcium chloride and heat treatment at various temperatures. It is shown that the moisture adsorption capacity Ca-bentonites without any additive are between 14%~17 % (w/w) upon by heat treatment whereas the addition of calcium chloride significantly, raised the moisture adsorption capacities.

Jan 1, 2014

By A. Makavetskas

"The purpose of the research is to study the mineralogical features of the structure of the wall accretion formed during melting on the working surface of the walls of metallurgical aggregates and adversely affect the stability of the lining of blast furnaces (BF). We presented the results of studies of the material composition of lining and wall accretion of the furnaces of blast furnaces of the metallurgical plant specializing in the smelting of ferromanganese, nodular and pig iron. It is established that the garnissage is an aggregate of layered texture, formed as a result of the crystallization of slag and metallic melts. Refractory calcium and magnesium silicates and aluminosilicates (minerals of the melilite group, leicite, olivine group minerals) and amorphous glassy oxide solid solutions of variable composition crystallize from the slag melts in the upper part of the hearth. In the slag matrix, inclusions of carbon (amorphous and graphite) and products of crystallization of metallic melts of alpha-iron, iron carbides and / or manganese are observed. Evidence of carbon evolution (in the form of graphite) is precisely in the crystallization of metal melts, there are significant differences in the structure of carbon in coke and in the garnissage. The conducted studies confirm that it is impossible to obtain reliable information on the material composition of new formations in the blast-furnace process without using a complex of modern methods of technological mineralogy.INTRODUCTION The formation of the wall accretion (garnissage) - a solid protective layer as a result of smelting products crystallization on the inner (working) surface of the liner. This is due to the design of blast furnaces with a high-efficiency heat sink using copper coolers and the use of carbon blocks with high thermal conductivity in the lining. The objective of the study was research of the material composition of the lining and wall accretion of the blast furnace hearth of one metallurgical plant that specialized in smelting ferromanganese, nodular and pig iron, to assess the effect of new formations for stability of the lining of blast furnaces (BF)."

Jan 1, 2018

By John A. Herbst, Ming Song, Xiangjun Qiu

It has been known for sometime that as wear occurs in tumbling mills there is an associated change in mill throughput. These changes have traditionally been simplistically, attributed to “mill volume effects”. New high fidelity simulation tools (involving DEM, CFD and Breakage models) are now giving new “microscale” insights into the complex interactions that occur between evolving lifter/liner profiles and breakage. The study described here shows that these new tools can allow the design of wear part profiles which will maximize mill productivity over the entire life of a liner/lifter system.

Jan 1, 2003

By H. Tiefel, M. Schneider, T. Neesse, J. Regler, J. Dueck, F. Donhauser

In practice the advantages of high-quality hydrocyclone separation are often reduced due to varying feed suspension properties, solids concentrations and particle size distributions. Control systems of large hydrocyclones are usually fitted with controllable underflow nozzles, which is not practical for small hydrocyclone batteries. Therefore, a new control system for a battery of hydrocyclones with a nominal diameter of 150 mm was invented at the LUR in cooperation with AKW Apparate und Verfahren GmbH & Co. KG. This process was developed for bentonite slurry regeneration associated with tunnel excavation using bentonite slurry as a transport aid and lubricant.

Jan 1, 2003

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

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

Jan 1, 2018

By Hong Zhong, Shuai Wang, Zhanfang Cao, Ting Dai

"Manganese is widely used in industries such as the steel industry and is now an essential element in modern industry. Technologies for the efficient and clean utilization of manganese resources must be developed and employed to ensure the sustainable growth of the manganese industry. Our research focuses on the use of beneficiation technologies to improve the grade of ores or the replacement of low-grade manganese carbonate ores with high-grade manganese oxide ores, and thus, to reduce reagent and energy consumption and the yield of electrolytic manganese residues from metallurgical processes; the study of leachate purification technologies; the study of electrochemical behaviors during electrolysis and energy-saving electrolysis methods; the development of chromium-free passivators as alternatives to the highly toxic potassium dichromate passivator; the non-hazardous treatment and resource utilization of electrolytic manganese residues and other manganese by-products; and the development of new manganese products. INTRODUCTION Manganese is widely used in the steel industry, nonferrous metallurgy, the chemical industry, electronics, batteries, agriculture, etc. Globally, more than 90% of manganese is consumed by the steel industry, and thus, it is said that ""No steel industry without manganese""(Banerjee et al. 2017, Zhang et al. 2017). Current manganese resources mainly include manganese ores, marine manganese nodules and waste catalysts. The total global output of manganese ore from land deposits is 18 million tons (metal volume), and the reserves, most of which is in the form of manganese oxide ores, are estimated to be 620 million tons (metal volume). More than 400 manganese ore deposits with a total reserve of 1.22 billion tons have been discovered in China. These deposits are predominantly manganese carbonate ores. Marine manganese nodules exist on the surface of the deep seabed at depths of 2000-6000 m. These nodules, which are also called polymetallic nodules, manganese balls, manganese aggregates and manganese tumors, are mainly composed of iron and manganese oxides. The total reserves of these resources add up to more than 3 trillion tons. Furthermore, the manganese in manganese-containing catalysts can be recycled after they become inactive."

Jan 1, 2018

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

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

Jan 1, 2018

By Antoineta Boteva

A significant part of the currently production of the non-ferrous and precious metals is from sulfide ores. Character feature of sulfide ores is the presence in them always pyrite and wide range of different sulfide minerals else. These minerals are the carriers of valuable for industry metals. Due to the low content of the main components, very often call on the use of collective- selective flow-sheets. The extraction of minerals in the collective concentrates determined in a large extent the effectiveness of the collective-selective sheets. In conditions of bulk flotation kinetics to floatate of the various minerals is different. Due to why it is and how it can be used for a more effective selection of minerals ?this is the main task of this report. For this purpose are used results from the bulk flotation of pyrite, copper sulfides, molybdenite, galena, blenda. It is separated and place of host rocks. Base it of large experimentation material, including both electro-kinetic measurements of mineral systems, as well as laboratory flotation tests and factories monitoring it is established kinetics of flotation of mineral particles in conditions of collective flotation. Made an effort to clarify the effect as of the species and the proportion of different sulfide minerals involved in flotation pulp else. Traced was the impact of the density and aeration of the flotation pulp on deferens in kinetics of mineral flotation in condition of balk flotation. The obtained results are used to increase the efficiency of the diffraction flotation of the complex sulfide ores containing precious metals. In the schemes, it is possible precious metals to fall in the most appropriate for the next processing products. Keywords: flotation, sulphide ores, kinetic extraction

Sep 1, 2012

By F. Z. Dong

The paper is mainly about a study on the techniques of separating iron from pyrite cinder of a certain sulfuric acid plant in Shandong province. The main components of the cinder are Fe2O3 and SiO2, and the degree of liberation of iron mineral and gangue is very high. So the iron concentrate with higher degree of iron and lower grade of silicon and sulfur can be achieved by reverse flotation. The iron grade of the concentrate reaches 63% and the recovery of iron is no less than 63%. And the most important influencing factor of the flotation is the temperature of the pulp. A better guideline can be achieved by magnetic separation. The cinder is magnetizing roasted for 15 minutes with temperature of 800?, and the concentrate with the iron grade 64%, sulfur grade 0.2% and iron recovery 85% can be obtained by two stage magnetic separation. A rotary kiln has been built to deal with the pyrite cinder, and the result of the industrial magnetizing experiment and magnetic separation is satisfying.

Jan 1, 2014

To extract the gold from refractory gold concentrate with high sulfur and arsenic, the gold concentrate was catalytically oxidized to expose the gold for cyanide leaching. The effects of reaction temperature, initial nitric acid concentration, reaction time and initial gold concentrate concentration on the conversion rate were studied. The results show that the appropriate conditions for the catalytical oxidation of this gold concentrate are: reaction temperature of 65 oC; initial nitric acid concentration of 25% (wt.); reaction time of 1.5 hours; initial gold concentrate concentration of 10% (wt.). Under such conditions, the conversion rate of gold concentrate is 92%. The solution can be used to prepare nano-iron oxide red pigment. Gases released in the process can be recycled and reused by oxidation absorption. A chemical background of catalytic oxidation is proposed.

Jan 1, 2014

By N. Acarkan

Beneficiation of the pyrite concentrate of the Kastomonu-Küre (Northern Turkey) copper ore seems to be attractive due to its high Cu, Co, and Zn contents. Pyrite concentrate were used in the experimental studies. Cu, Co, and Zn were recovered from the concentrate by the sulphatizing roasting, leaching and the precipitation using H2S. Sulphatizing roasting experiments were carried out in a rotary furnace and the optimal roasting conditions were found to be at 650°C roasting temperature and 3.0 h roasting period and addition of Na2SO4 of 3 % for the concentrate containing 0.58% Cu, 0.22% Co, and 0.04% Zn. Then, the roasted product was repeatedly leached with 10 g/L H2SO4 solution. Optimal conditions were found to be 60 oC leaching temperature, 2 h leaching period, and 30% pulp density. Leaching efficiencies for Cu and Co were over 99 %. The valuable metals in the pregnant solution were selectively precipitated by H2S as sulfides. Selective precipitation of Cu, Zn, Co was achieved by adjusting the pH and the temperature of the leach solution. Final metal recoveries of 99.20% Cu, 99.40% Co, and 95.60% Zn were attained. The precipitated sulphides are marketable products. Roasting gases with their 15% SO2 content are suitable for the production of H2SO4 and the leach residues can be integrated with the iron ore processing plant as they contain 57.50 % Fe, 17.70% gangue (SiO2, CaO, etc.), 0.04% S, and 0.06% non-ferrous metals.

Jan 1, 2014