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By Sunil Tripathy, Y. Rama, Srinivasulu. A., Amit Ranjan

Process improvements in an operating plant are always challenging. Mineral beneficiation plants based on gravity concentration techniques need continuous evaluation and monitoring of its processes for getting maximum recovery and better grades. But, in an operating plant it is very difficult to control all the parameters due to numerous reasons such as unsteady operation, fluctuation in the quality of run-off-mine ore, overall flow rate etc. For better understanding of the beneficiation circuit, it is necessary to evaluate the critical operating parameters which affect the performance in terms of grade, recovery and throughput including losses of valuable materials into tailing. Accurate data collection and proper data interpretation followed by making necessary change which is implementable in an operating plant play very critical role in performance of the circuit. In case of gravity operated beneficiation circuits of chrome ores where the quality of the feed and physical parameters varies continuously, the operators are required to modify the critical operating process parameters on continuous basis which is very difficult and tiresome. There are many causes of the data variability, including both error (sampling and assay), and real variation in performance due to changes in ore mineralogy, operating conditions and other factors. In this article, attempts made to evaluate the performance of ultra-fine beneficiation circuit in terms of silica reduction in the concentrate of chrome ore beneficiation plant (COB), India are discussed. The approach adopted and practical problems encountered during the study were also discussed. Results obtained from plant audit based on the above methodology has shown that SiO2 content in the concentrate can be reduced to <4%.

Jan 1, 2014

By G. V. S. Murthy

Beach Placer Ilmenite is an important source for production of titanium metal, titania slag and pigment grade titanium dioxide. Besides, these well known applications for which Ilmenite is mined and processed, there are other emerging processes that are being tried for obtaining highvalue products. Synthesis of Ilmenite based materials for varistor applications and direct electrochemical reduction of Ilmenite to produce ferrotitanium are two such attempts being discussed in this work. In this paper, recent efforts undertaken to study the electrical and magnetic characteristics are discussed. Ilmenite, FeTiO3, is one of the mixed-valence transition metalbearing minerals, inwhich Fe can be in two different oxidation states, Fe2+ and Fe3+.. Similarly, Ti can be in Ti3+ and Ti4+.Ilmenite is inherently suitable for making Varistors, which are devices, used for limiting the transient voltage surges in a circuit. Varistors produced from Ilmenite can withstand harsh environments seen in nuclear reactors and outerspace. Electrochemical reduction of Ilmenite can be used to prepare ferrotitanium directly without any reductant. The process essentially involves removal of oxygen from the mineral through electrolytic action using calcium chloride as electrolyte and graphite as anode. At a temperature of 950°C, it is shown to be possible that all the oxygen can be removed from the Ilmenite sample, which passes through the electrolyte, to form CO/CO2 at the anode. The process has immense potential for cost effective production of titanium metal as well. Results of the above developmental works are presented in this paper. Keywords: beach placer ileminite, varistor applications

Sep 1, 2012

By O. N. Mohanty, S. Mohan Rao, N. D. Rao, T. Mukherjee, P. V. T. Rao

"Tata Steel has its captive chromite resources at Sukinda, Orissa. They contain two ore types, i.e. (i) Ferruginous and (ii) Siliceous. The generation of off-grade ores is an increasing trend and simultaneously customer quality requirements are becoming ever more stringent. The ferruginous type ore also contains a considerable quantity of in-situ fines (~20% particles below 0.5 mm) that compound the beneficiation problem.In this paper, new strategies are discussed for producing additional value.added products after evaluating the present beneficiation practice in terms of changing market scenario, processing capability of the plant and ore characteristic. They would entail use of MGS - an enhanced gravity separator, for recovering additional products from plant tailings; production of ferruginous coarse concentrates (-3+0.5 mm with ~46% Cr2O3) using jigs; production of marketable grade lumpy (-40+10 mm size) concentrates from low grade siliceous ore using jigs and >2.8 Cr/Fe ratio siliceous ore fines treated in the Chrome Ore Beneficiation plant gravity circuit units and low intensity magnetic separator. The studies indicate that it is possible to recover 79-80% of the chromite, against a theoretical maximum of 82% from both the ore types, in the form of several marketable grade concentrates that would also include refractory grade."

Jan 1, 2003

By Gaom M. W.

The Mount Isa copper concentrator started operation in 1973. Its secondary grinding circuit consisted of two 5 meters diameter ball mills in closed circuit with 505 mm cyclones. At the design throughput of 800 t/h, the 80% passing size of the circuit product (P80) was about 140 µm. The then Mount Isa Mines Limited (?MIM?) installed two autogenous grinding (?AG?) mills in 1991 to replace two stages of crushing, a rod milling stage and one primary ball milling stage. One of the AG mills was later converted to semi-autogenous grinding (?SAG?) operation by the addition of a steel grinding medium to achieve the designed plant throughput of 800 t/h. The cyclone over-flow P80of the secondary ball mill circuit was reduced to 120 µm by the increased operating power in the AG/SAG mill circuits. The two secondary balls mills had a grinding power of 5.2 MW. A mineralogical study of the milled products indicated that half of this grinding power was sufficient for adequate chalcopyrite liberation. Eliminating one of the secondary ball mills could reduce energy and operating costs by more than A$2 million dollars per year. An optimisation project team was established to achieve the predicted power saving. Grinding circuit simulations were conducted for different circuit configurations. Ball mill parameters such as ball size, ball charge and feed slurry density were optimised. Cyclone body diameter, spigot and vortex finder sizes, and cyclone types were tested. The secondary ball mill circuit was redesigned and several proposed circuits were run as trial production campaigns to determine their operability and efficiency. The plant trials confirmed that one of the secondary ball mills could be decommissioned. Significant cost savings were achieved as a result. The success of the project demonstrates optimising grinding circuits can not only deliver the plant performance, but also a much lower unit operating cost through energy and maintenance savings.

Jan 1, 2014

By C. Dorfling

Experimental work was performed using a bench scale autoclave to evaluate the effects that leaching temperature, pressure, initial acid concentration, and the solid to liquid ratio have on the behaviour of base metals and platinum group metals in a high-pressure sulphuric acid oxygen leaching system. The concentrations of metals in the leach solution were measured over time at different leaching conditions. At the conditions investigated, the initial acid concentration had the largest influence on the copper leaching kinetics, while the leaching rates of the other precious metals (OPMs: rhodium, ruthenium, and iridium) were highly dependent on the leaching temperature. A set of chemical reactions that can be used to describe the leaching chemistry was proposed, and the associated reaction kinetics were quantified. As a first estimation, the rate expressions were considered first order, and the rate constants were determined using the method of least squares, considering the experimental and predicted concentrations obtained for the different leaching conditions. Of the OPM compounds, the sulphides showed the fastest dissolution rate, followed by OPM alloys, and finally the OPM oxides. During the initial leaching stages, base metals and OPMs competed for the available dissolved oxygen, with oxygen being preferentially used for copper leaching. Precipitation of OPMs during the initial leaching stages can be ascribed to copper and nickel dissolution according to exchange reactions between dissolved OPMs and copper present as digenite or nickel present as polydymite. Control of the autoclave residence time is of particular importance to enhance the selectivity of this leaching step, given the dependence of the PGM leaching rates on the extent of copper dissolution.

Sep 1, 2012

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 J. K. Afidenyo

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

Jan 1, 2014

By Willis Forsling, Prabhakar Swarna, Hanumantha Rao Kota

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

Jan 1, 2003

By J. Yianatos

The cleaning circuit operation and its effect on the plant metallurgical performance, was characterized at Los Pelambres concentrator, Chile. Experimental data from columns, scavenger and regrinding stages was evaluated. Each stage was characterized by size fractions, and the interaction between stages (columns, scavenger, regrinding) as well as the effect that circulating loads had. The approach for describing the flotation equipment operation (cells and columns) considered the collection and froth zones separately. This methodology allows for the identification of the impact that particle size distribution has on the actual collection and froth transport processes, independently. In this way the effect of regrinding on flotation recovery and grade can be related to the corresponding operating variables, e.g. pulp flowrate, air flowrate, pulp level and pulp density, among others. The effect of gangue entrainment was considered using an empirical dimensionless correlation. The interaction between the circulating load and the overall performance of cleaning circuit was evaluated. The circulating load was defined as the ratio between the solid flowrate of scavenger concentrate over rougher concentrate. It was found that the overall cleaning flotation circuit (column-scavenger) can operate at a relatively high and constant recovery for a wide range of mineral treatment. This is possible when the scavenger has the capacity for compensating the decrease in column recovery at larger circulating loads. Under the condition of high overall cleaning recovery, the rougher stage closely represents the plant recovery. However, at large mineral treatment conditions, the design characteristics (e.g. concentrate transport channel capacity and transfer boxes) as well as instrumentation, control facilities and operation, became bottle-necked. A simulator was developed using empirical models for each stage (column, scavenger and regrinding) in order to evaluate proper operational strategies for cleaning flotation circuits Keywords: flotation, cleaning, regrinding, Vertimill, simulation.

Sep 1, 2012

By V. A. Chanturiya

The state-of-the-art of mineral mining and metallurgy industry in Russia is characterized by high demand of nonferrous, rare, rare earth metals, and highgrade coal, on the one hand, and by involvement of natural and technogenic minerals with low content of valuable components, fine (nearly emulsion) dissemination of valuable components and close physicochemical and process properties. This calls for high-productive and ecology-friendly technologies for more efficient mineral beneficiation based on intensification of operating and new methods to extract valuable components from rebellious ore and technogenic minerals, relying on the last achievements of basic sciences, combination of dressing and chemico-metallurgical processes and using advanced pyro- and hydrometallurgical technologies. The transition to a new strategy of processing is only possible based on the new technological–mineralogical appraisal of a mineral raw material. Actually, the process mineralogy has a stock of modern high-resolution physical methods for analyzing composition, structure and properties of geomaterials, inclusive of micro- and nano-levels: - Identification of micro- and nano-size noble metals, and natural and induced formations on mineral surface; - Experimental validation of structural phase and chemical transformation of minerals under different energy input; - Justification of choice and mechanism of interaction between flotation agents and noble metals with complex material constitution; - Analysis of structural, phase and chemical transformations of sulfides and rocks under leaching. Thus, process mineralogy is an informational background for a unified theoretical approach to scientific justification of flowsheets of efficient mineral processing. The article gives a brief review of practices that have found application and proved to be of high economic efficiency. Such practices are: X-ray radiometry and photometry separation (Uchalinsky and Gaisky Mining and Processing Integrated Works of ALROSA); selective disintegration (equipment engineered by Mekhanobr-Tekhnika and IPKON RAS); process selectivity enhancement (IPKON RAS, Central Research Institute for Geological Exploration of Nonferrous and Noble Metals, Chinakal Institute of Mining, Siberian Branch RAS, etc.); bacterial gold leaching (Olimpiada MPIW, technologies developed the Central Research Institute for Geological Exploration of Nonferrous and Noble Metals, Nezhdaninsky deposit projects, etc.); combination processing at a mining and metallurgy plant (Norilsk Mining and Metallurgical Company, Yaregsky deposit projects and others); processing of waste: overburden, mill tailings, slag, etc. (Kovdorsky MPIW, Svyatogor JSC, Ural Mining and Metallurgical Company, plants designed by the Central Research Institute for Geological Exploration of Nonferrous and Noble Metals, Mining Institute of Kola Science Center RAS, Research Institute for Chemical Technologies); water conditioning in mineral dressing circuits (ALROSA, equipment by IPKON, etc.); utilization of process water (ALROSA, Ural Mining and Metallurgical Company, Severalmaz JSC and others). Thus, Russia this time has the academic and engineering background for development of efficient energy-saving technologies for comprehensive advanced processing in accordance with the world’s standards, or even higher in terms of a number of the technologies, which has continually been highlighted by participants of recent international congresses on mineral processing.

Jan 1, 2018

By Kyle P. Flynn, Frank J. Hrach, James D. Bittner

ST Equipment & Technology, LLC (STET) has developed a processing system based on tribo-electrostatic belt separation that provides the mineral processing industry a means to beneficiate fine materials with an entirely dry technology. In contrast to other electrostatic separation processes that are typically limited to particles greater than 75µm in size, the triboelectric belt separator is ideally suited for separation of very fine (<1µm) to moderately coarse (300µm) particles with very high throughput. The high efficiency multi-stage separation through internal charging/recharging and recycle results in far superior separations that can be achieved with a conventional single-stage free-fall tribo-electrostatic separator. The triboelectric belt separator technology has been used to separate a wide range of materials including mixtures of glassy aluminosilicates/carbon, calcite/quartz, talc/magnesite, and barite/quartz. An economic comparison of using the tribo-electrostatic belt separation versus conventional flotation for barite / quartz separation illustrates the advantages of dry processing for minerals.

Jan 1, 2014

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 D. Pienaar, B. McFadzean, T. Jordaan

"Dithiophosphate (DTP) collectors have the lowest affinity for sulfide mineral surfaces compared to other common sulfide mineral collectors, such as xanthates and dithiocarbamates. In some cases it has been found that DTP does not adsorb onto the mineral surface at all and yet increases in recoveries and grades are noticed with the addition of DTP. Many studies have investigated the interactive effects of collector mixtures. However, there have been relatively few studies on the interactive effects between frother molecules and collectors. This study investigates the interactions between different types of frothers and sodium diethyl dithiophosphate.The study found that there were large increases in pyrite and galena microflotation recoveries at both pH4 and pH9 when DTP was mixed with small amounts of frother at a constant bubble size, showing that these increases were neither mineral-specific nor pH-specific. The same effect was not present when xanthate was used as a collector. The increases in recovery when using the DTP-frother mixture were similar irrespective of the type of alcohol or polypropylene glycol frother that was used. In an attempt to distinguish the mechanism of enhanced flotation recovery, various supplementary experiments were performed. It was found through adsorption experiments that no DTP was adsorbing on to the mineral surface. Therefore, interactions at the air-water interface were performed. Surface tension and critical coalescence concentration tests showed that, while DTP is a weak surfactant at the air-water interface, it does not have a synergistic effect in the presence of frother. DTP-frother mixtures do, however, show interactions in the froth phase, indicating an interaction in the thin films. It is proposed that there is a DTP-frother interaction on the bubble surface that enhances the rate of film thinning at the 3-phase bubble-particle contact."

Jan 1, 2018

By Megha Patel

"The objective of this project was to investigate the application of Prompt Gamma Neutron Activation Analysis (PGNAA) technology to provide real-time on-belt elemental analysis of feed ore in base metal sulphide processing, in this case at the Mount Isa Mines Zinc-Lead Concentrator Heavy Medium Plant (HMP). After initial exploratory testwork proved successful, a Geoscan On-Belt Elemental Analyser was retrofitted onto the existing HMP feed conveyor. Dynamic calibration of the Geoscan was conducted based on laboratory XRF analysis results of the HMP feed conveyor hammer autosampler samples from May to November 2013. Comparison of the Geoscan results to the laboratory XRF analysis results during and after dynamic calibration indicated the technology had acceptable accuracy to be incorporated into HMP process control. The variation between the two sets of data includes all primary sampling, sample preparation and XRF analysis errors as well as the Geoscan errors themselves. The Geoscan instrument precision must be calculated separately through a duplicate sampling campaign and independent laboratory analysis before extending the scope of its range of application beyond HMP process control. The expected benefits of integrating the Geoscan real-time data into HMP process control are optimised HMP metal recovery, improved cost efficiency and improved stability of the downstream processes (milling and flotation). Utilisation of the Geoscan will also enable improved feedback to mines on grade control and dilution, and provide additional information on individual ore types when fed as campaigns to HMP."

Jan 1, 2014

By Khoi Nguyen, Keeney. Luke

An outcome of geometallurgical mapping and modeling is the generation of continuous down hole profiles of quantitative geometallurgical attributes at assay scale. These attributes vary from traditional routine data collection methods such as assays and geotechnical logging (e.g. RQD, Fracture Frequency), to new measurements including petrophysical attributes, EQUOtip hardness data and modelled estimates of metallurgical performance indices (e.g. A*b, BMWi). Highly variable continuous geometallurgical data with high spatial resolution can make it difficult to identify spatially continuous domains. An automated method based on the well known time series analysis technique of cumulative summation (CuSum) has been developed which uses statistical analysis to identify domain boundaries in down hole profiles. A bootstrap analysis automatically identifies potential domain boundary locations with associated confidence levels and a series of t-tests determine the significance of defined populations. A hierarchical clustering algorithm is applied to results to enable data sensitivity to be taken into account. The method produces statistically significant populations and is suitable for application on either single or multiple drill hole datasets. Domains defined preserve the inherent variability of the continuous down hole data and provide a method for scaling up variability data (i.e. assay interval scale) to mine scale (i.e. bench scale, block model). A major advantage of the method is its ability to provide suitable input parameters for use in spatial modeling of non-additive and non-linear geometallurgical attributes through conditional simulation techniques.

Jan 1, 2014

By S. K. Kawatra, T. C. Eisele

"Coal-fired electrical power generation plants produce 56% of all the electricity in the U. S., burning approximately 860 million tons of coal annually. This results in production of 58 million tons of fly ash; 19 million tons of bottom ash and boiler slag, and 23 million tons of desulfurization sludges. These are a considerable disposal problem, and it would therefore be very valuable to be able to sell these residues and byproducts as useful materials, rather than paying to dispose of them in landfills. However, utilization rates are currently very low, below 32% even for the most thoroughly commercialized combustion byproduct (fly-ash). This poor utilization rate is a result of the high impurity content of combustion byproducts, which make them unsuitable for existing markets. The experiments described in this paper were therefore carried out to study the application of mineral processing techniques to upgrading combustion byproducts.Experiments were conducted to upgrade and purify low-grade combustion products to produce highgrade, readily saleable materials. A process was developed for removing unburned carbon from coal fly-ash by froth flotation, using reagents originally developed for flotation of oxidized coals. This technique could reduce the carbon content of fly-ashes containing up to 11.1% carbon to less than 2%. The froth product was sufficiently carbon-rich that the recovered carbon has value as fuel, or as low-grade activated charcoal.Fly ash was also examined as a binder for producing iron ore pellets, primarily as a substitute for bentonite. It was found that Class F fly ash in combination with an activator (calcium hydroxide) was an effective pellet binder at dosages comparable to the currently-used dosages of bentonite clay. While the flyash worked very well alone, tests in combination with bentonite showed that fly-ash/bentonite mixtures had significantly worse binding performance than either pure bentonite or pure fly-ash-based binder. This was determined to be due to the fact that bentonite and fly ash have profoundly different binding mechanisms, with fly-ash undergoing a pozzolanic chemical reaction while bentonite binds through a physical attachment process."

Jan 1, 2003

By J. K. Qu

As one of the key inorganic chemical industries, the chromate chemical industry has spawned extensively public concerns due to the resulted environmental pollution. The cleaner production technology for chromium compounds bases on sub-molten salt medium developed by the Institute of Process Engineering, Chinese Academy of Sciences has greatly decreased the reaction temperature and energy consumption, significantly in-creased the utilization ratio of the chromium element, and successfully achieved the comprehensive utilization of chromite resources and zero emission of chromium-containing residue. The separation process of production is the most important components in the cleaner technology. In this work, we studied two parts: the first is the removal of SiO2, Al3+ from the system and the recycling utilization of alkali metal medium through adding Ca(OH)2 and CaO; the second is to get more pure K2CrO4 crystalloid and remove K2CO3 from KOH solution through evaporation to prepare raw material for manufacturing Cr2O3 and get 50%(wt) KOH. The results obtained show that Ca(OH)2 can remove Al3+ more than CaO and has lower caustic ratio than CaO when they were added 110% of theoretic quantity. The optimal pure K2CrO4(96%) can be gained at 45 Celsius degree in 30% KOH solution and K2CO3 in 50% KOH solution could be decreased to 3.5%(wt) at 40 Celsius degree. And then K2CO3 can be causticized with adding Ca(OH)2 to recycle potassium alkali. The impure material can be re-moved and suitable raw material for manufacturing Cr2O3 can be gotten and reaction medium can be also recycled in this process technology, realizing cleaner production effectively.

Jan 1, 2014

By Güven Önal, Zeki Dogan, Neset Acarkan

In this study, it was aimed to produce glass sand with less than 0.15% Fe2O3 for window glass manufacture and glass ware grade with less than 0.05% Fe2O3 from Yalõköy sand dunes having 0.48% Fe2O3. In order to reduce the iron content of the Yalõköy sand dune, magnetic separation, flotation, scrubbing, H2SO4 leaching and drying were used. The optimum iron removal was achieved by H2SO4 baking at 150oC and 8 kg/t acid consumption. In this way, sand concentrate was obtained with 0.04% Fe2O3 and sand recovery 95%.

Jan 1, 2003

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 G. X. Du

Reaction kinetics of serpentine and hydrochloric acid is theoretical basis for optimizing reaction process conditions of serpentine and hydrochloric acid. Kinetics of serpentine and hydrochloric acid was studied in this paper. The results indicated that apparent reaction order to hydrochloric acid was two and reaction kinetic equation could be expressed as: 2HClHCl,ddtckct-=·. The diffusion rates of hydrogen ions in liquid film on surface of serpentine particle and in amorphous silica layer generated in the reaction and chemical reaction velocity during the reaction had important effects on to-tal reaction velocity. And chemical reaction velocity had the most significant influence. The relation of conversion rate of magnesia xMgO with reaction time could be expressed as: 1(1)xkt--=·.

Jan 1, 2014