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The generation of acid mine water is? due to the oxidation and weathering of sulfide bearing tailings and overburdens. Ferrite precipitation prooess has been applied to treat acid mine water. The conventional ferrite preC1pitatlon requires air oxidation at high temperature, or long aging time or addition of magnetite powder ,as promoter. In this investigation, a modified ferrite, precipitation process is developed by which magnetic ferrite can be produced at an ambient temperature. Acid mine waters from Berkeley Pit (Montana, U. S. A.) and from Noranda Tailings (Quebec, Canada) were used. The co precipitation of heavy metals from these two acid mine waters is studied as a function of FeIM molar ratio, oxidation time and settling rate under applied magnetic field. The investigation indicates that the modified ferrite co precipitation can remove substantially all of the, dissolved metal ions from acid mine water. The ferrite product obtained after precipitation' is characterized by XRD, SEM, BET and saturation magnetization. The results show that spinel ferrite, precipitation can be achieved at room temperature and the saturation magnetization of ferrite product from,acid mine water is comparable to that of pure ferrites.

Jan 1, 1995

By L. Becze, S. J. Hock, G. P. Demopoulos

"Regeneration of HCl from chloride solutions is commercially practiced by high temperature (800-900 °C) pyrohydrolysis associated with high energy consumption and capital cost. As an alternative to pyrohydrolysis a novel low temperature ( <200 °C) non-autoclave hydrolytic process has been studied in this research work, which comprises two steps. In the first step, ferrous chloride is oxidized by oxygen at 1;150 °C, followed by hydrolytic decomposition of ferric chloride to coarse hematite particles and superazeotropic hydrochloric acid (8-9M) operated at approximately 180 °C. This paper provides a summary of the laboratory results related to both oxidation and hydrolysis and presents a newly designed conceptual process flowsheet.IntroductionRecovery of base, noble and rare metals from ores and secondary materials (slags, dusts, residues) by chloride-based hydrometallurgical processes holds a lot of promise if a low cost HCl process becomes available. This is particularly so due to the high activity of HCl or more accurately activity of hydrogen ion [1] in concentrated chloride media and the formation of chlorocomplexes allowing for effective leaching under atmospheric leaching conditions and simultaneous ease of metal separation. However, during leaching significant amount of iron, which is associated with most of ores and secondary materials, goes into the solution. Hence, the obtained leach solution has to be treated to convert iron chlorides into easily filterable iron oxide and simultaneously produce concentrated hydrochloric acid. Apparently the critical operation of these processes is the regeneration of the lixiviant (HCl). Currently in the industry, its regeneration is accomplished by high capital and intensive pyrohydrolysis which operates at 700- 900 °C. Aimed at lowering the operational cost of pyrohydrolysis a process called PORI [2] was developed and tested in pilot plant scale in the 1970s for the purpose of treatment of pickle liquors without, however, resulting in industrial application."

Jan 1, 2011

By Enrique Posada

"The Valle de Aburrá area, corresponds to the city of Medellín and neighboring municipalities, with more than 3 million people. The area generates a sizable amount of solid waste, which has been taken to landfills for the last 20 years. This paper proposes a model for public policy making which considers the cost and benefit of different alternatives to handle the wastes in the coming 20 years. Combinations of several alternatives: Recycling, waste reduction, waste separation, incineration, land filling with lixiviate treating and gas energy recovery, and organic waste composting are considered and modeled and the results presented as a contribution for a more rational approach to policy making than the one currently being employed.IntroductionThe author, working for INDISA S.A., acted as a consultant for the direction of planning of the Empresas Varias de Medellín in 2004. This entity has the responsibility for the handling of the solid wastes of the city of Medellín and some of the neighboring municipalities. At the present time more the 700.000 annual tons of waste are taken to the site of La Pradera, located in very rainy location (3.000 mm of precipitation per year), with complex in topography and very far away from the sources of the waste. During the work the author detected important problems that should be addressed, as follows:Lack of adequate technical administration and resources. The entity did not count with sufficient human resources to focus on the appropriate technical handling of the solid waste. The organization worked mostly with independent contractors, lacking enough coherence and integration. The internal workload was too large for the few people who had technical responsibility and this gave rise to attention problems. It is important to have clear technical procedures, technical know how and human resources, continuity in the activities. It is important to have a clear capacity to plan, to study, to make tests and monitoring, to pursuit and develop ideas, to optimize the processes and to introduce changes, to respond to environmental authorities, to the communities and to mass media and to handle the contractors. All this was basically lacking. In the case of the handling of the sanitary filling of La Pradera, for example, although the people in charge were very able and dedicated, the magnitude of the task was too large and the resources they had were insufficient. As a result, the site had at the time of the study, problems with thousands of vultures, lack of immediate cover up for the waste, uncontrolled leaching, the area being dirty and little attractive, despite being called a park."

Jan 1, 2008

By Akira Kaneda

Mitsubishi continuous process employs an electric furnace for settling matte from slag. Electrodes are immersed into the slag layer in the slag-cleaning furnace and the temperature of the melt is maintained at a predetermined level by Joule&apos;s heat. Electrodes are immersed to the depth where the current of each electrode is kept at a set value, and they are raised or lowered automatically to compensate for the deviation from it. Because electric resistance of the bath is varied with the matte level in the furnace and the composition and temperature of the slag, the immersion depth of the electrodes is affected by them. Therefore by monitoring the immersion depth and its change with time, abnormal situations in the furnace, such a~ rise of matte level or local abnormal state of melt, can be detected. In this paper, relations between state of the furnace and electrode behavior are discussed based on the plant data, and then a new and simple monitoring method of the condition of the furnace is proposed.

Jan 1, 2001

By A. M. Blount

In 1983, a final ruling of the U.S. Occupational Health and Safety Administration (OSHA) specified that chemicals containing >0.1 % of a carcinogenic substance or > 1 % of a substance hazardous to health must be labelled. Amphiboles of the fibrous or asbestos-type must be quantified at levels of 0. I % whereas the status of non-fibrous types is not finally determined at this time. Tremolite and actinolite can possibly be measured to 0.1 % by XRD, but anthophyllite cannot be so measured. Recently the International Agency for Cancer Research (IARC) has designated quartz as a suspected carcinogen, and its quantity must be measured to the 0.1 % level. Thus, it has become Increasingly important to be able to detect and quantify minerals in bulk samples down to low or "trace" levels. It has been found that minerals needing to be quantified can often be concentrated by microcentrifuge and counted by means of polarized-light microscopy. For example, amphiboles in talc samples can be separated by using a heavy liquid (thallium formate-malonate) of density 2.810. Talc floats, and amphiboles sink. After centrifuging, the denser particles are removed from the bottom with a Pasteur pipette and placed in a clean centrifuge tube. Distilled water is added to the tube containing the denser minerals and the tube centrifuged again. After several washings with distilled water, the sample is removed along with a drop of water to a clean glass slide. A drop of 1 .584 refractive index liquid and a cover glass are placed over the dried sample. The slide is scanned for particles greater than 5 um in length and having an aspect ratio greater than 1:3. These are checked for refractive index, sign of elongation and extinction angle to differentiate them from talc particles on edge and other minerals. Amphiboles have all indices greater than 1.584, and talc has all indices equal to or lower than this value. Alternately the heavies at the bottom of the centrifuge tube can be filtered through a nucleopore filter. After the filter has been washed with distilled water and dried, a 1.584 refractive index liquid renders the filter transparent in two of the four extinction positions so that a count of amphibole particles can be made directly on the filter. The refractive index-density method which is so useful for talc powders should be equally useful for other nonsoluble industrial minerals.

Jan 1, 1989

By Dirk Verhulst

The Altair process employs digestion of ilmenite ore in concentrated hydrochloric acid, solvent extraction to concentrate Ti in a purified stream and spray hydrolysis to produce a TiO2 hydrate, followed by final calcining and milling. HCl gas is regenerated by pressure-swing distillation and reinjected in the leaching solution. All chloride streams are recycled. Chromium compounds generally remain in the residue. Solvent extraction provides flexibility for the removal of naturally occurring radioactive elements (NORMs) present in some ilmenites. The process was previously tested at a 5 t/day feed scale. Recent work at pilot scale (40 liter reactor) led to further improvements. Recovery of Ti in solution is now at least 90% with ilmenite ores, while crystallization at lower temperature lowers the amount of Fe in solution to about 5 g/l and improves solvent extraction, which is now conducted in columns. Higher Ti and lower Fe concentrations in the SX eluate improve the economics. A new formula for pigment production via spray hydrolysis produces a pigmentary base with a narrow particle size distribution.

Jan 1, 2003

By Bo Zhou

During secondary aluminum recovery, complex aluminum scraps are melted and refined often in a rotary melting furnace and the aluminum metal has to pass through a molten salt layer and melt down in a bottom aluminum bath. Previous experimental study and industrial observations have indicated that salt shell formation and re-melting on the metal solids in the early stage plays a critical role in the overall melting process of the scrap. In the present paper, mathematical models are developed to simulate the process of salt shell formation and its re melting, as well as aluminum melting in the molten melt. Influence of the salt layer properties, the residence time of the metal particles in the salt layer, the particle size, the temperature of bulk melt were investigated. Reasonable agreement with the measurement data was reached. The developed melting model will be used to construct a population balance model of the scrap melting behavior for a rotary melting furnace, taking into account the distributed characteristics of the scrap. Finally, an overall process model based on Computational Fluid Dynamics (CFD) for the rotary furnace will be constructed, coupling with the population balance model for the scrap melting.

Jan 1, 2003

By K. B. Dotson

A common international safety and health management system was developed. Analysis of selected major safety and health management systems from around the world was conducted. Functional elements of selected systems were grouped to identify common elements and key differences. Common elements were subjected to qualitative judgments of equivalency and then reconciled. With few exceptions, differing elements were revised to achieve cultural neutrality. The resulting 98 system elements were organized according to the NOSA numbering and title scheme. System summaries were produced in Spanish and English. A pre-implementation self-assessment evaluated conformance in three distinct cultures. The consensus 98 element system was internally named the BHP Copper Five Star Safety System Performance Management Guidelines. Development of a common system within an organization with international operations can enhance the ability of the staff function to share resources, programs and subsystem improvements and thereby increasingly protect workers. Common systems can increase the level of management support by demonstrating increased compatibility of the safety and health management function with traditional business objectives. Safety professionals, industrial and occupational hygienists, business managers and the safety and health of workers will benefit from further development and articulation of common systems for safety and health management.

Jan 1, 1999

By Takeshi Azakami

By combining the iron reduction process with the usual rotary kiln process, the direct production of metallic zinc from EAF dust is proposed. After thermodynamic estimation and desk-top experiments it is confirmed that the process is hopeful under suitable conditions. In order to get some practical test data the enlargement of the process scale was planned and the bench scale tests were carried on successfully. In these experiments a zinc ingot of PW grade was produced from EAF dust.

Jan 1, 2003

By Ullrich Kammer

Metaleurop&apos;s secondary lead smelter at Oker produces 60.000 mtpy of lead and lead alloys. More than 8O2 % of the raw materials are spent lead acid batteries. The other 2O2 % consists of drosses, ashes, scrap lead, type metal, sludges, etc., and is processed in a short rotary furnace (SRF). Also, industrial batteries not fitting in the battery scrap treatment plant are processed in the SRF provided with gas/oxygen-burner. Till Sept. 199O2, a soda ash slag was used in the SRF-smelting similar to the rotary kiln-smelting at Oker. Facing the future problems of handling and dumping soda ash slag, Harz-Metall GmbH has improved SRF-smelting with a non¬hazardous slag, insoluble in water, easy to dump and cheap in fluxes. This slag is based on a CaO-SiO2 -Fe0-type. Aim of the slag smelting is to be within the temperature range of 2 1100° and 1200°C - the eutectic line of Olivine in the corresponding ternary system. Since Sept. 199O2 Harz-Metall GmbH has operated the SRF with an "Olivine-type slag" with good results. Although the material is a "leady" slag. HMG is optimistic of using it as a filling material for construction purposes.

Jan 1, 1993

By Yuri Gelfgat

"This paper presents some results of the investigation of the steady magnetic field influence on hydrodynamics and heat/mass transfer in processes of semiconductor single crystal growth (Si, Ge, InSn). The investigation employed mathematical and physical simulation techniques of relevant processes and full-scale experiments on growth facilities. A number of additional MHD phenomena have been found generated in the melt due to the rearrangement of flow pattern, the formation of specific convective cells, and the origin of MHD boundary and shift layer.IntroductionMagnetohydrodynamic (MHD) means of creating forces by contact-free methods in liquid conducting media have been widely used in the production of volume semiconducting single crystals. The goal of this method is to control convective transfer processes in the melt volume and on the crystallization front [1-3]. This is due to the sufficiently high conductivity of semiconductor melts (s = 104 /106 O1m-1 ) and an obvious relationship between the hydrodynamics in the melt and at interfaces and the conditions of formation of single crystals and their quality [ 1].All types of MHD effects rest upon the generation of volume electromagnetic forces in the melt by various means as well as on the possibility to direct them arbitrary in space and to adjust easily their absolute values. Fig. l presents different means how to implement MHD phenomena during single crystal growth. It should be emphasized that in all the modifications given in Fig. l additional energy introduced into the melt cannot influence directly the crystallization process since it is incomparable to the energy of molecular forces. Both the influence and efficiency of MHD means are determined solely by the change of motion, heat and mass transfer characteristics."

Jan 1, 1998

By Batric Pesic

Gold dissolution with bromine was studied by using the rotating disc technique. Geobram TM 3400 was used as a source of bromine. The parameters studied were: rotating speed, Geobrom 3400 concentration, pH, temperature, sulfuric and hydrochloric acid concentration, and the concentration of various cations (copper, iron, zinc, aluminum, manganese, potassium and sodium) and anions (chloride, bromide, sulfate, nitrate, and iodide) According to the Levich plot and activation energy, gold dissolution was controlled by a chemical reaction rate. Copper, iron, and manganese in their highest oxidation states, aluminum, zinc, sodium and potassium did not have any effect on gold dissolution rate. The presence of manganous ion dramatically decreased the gold dissolution rate. Kinetic performance of bromine, in the form of Geobram TM 3400, was compared with performance of cyanide and thiourea.

Jan 1, 1990

By Xianwen Dai

One of the biggest challenges for the gold industry in the 21st century is the presence of copper in gold containing ore bodies. This is because copper consumes large quantities of cyanide. In addition, copper cyanide species are more stable than free cyanide, and hence are problematic in events of tailings spillage. The present paper compares cyanide and thiosulfate leaching for the recovery of gold from a copper containing ore. For cyanide leaching, the extraction of gold using copper cyanide complexes instead of free cyanide was tested in the presence and absence of added ammonia. For the thiosulfate leaching, the effect of the minerals present in the ore on the solution potential and thiosulfate consumption are illustrated.

Jan 1, 2003

By William Bourcier

Geothermal Brines are a significant potential source of valuable minerals and metals. These brines are water that is heated by the natural heat flow from the depths of the earth. Hotter brines, typically with temperatures greater than 120°C, are used to generate electricity. Lower temperature brines are directly used to supply thermal energy to applications such as agriculture, aquaculture and process/domestic heat. The geothermal waters have had intimate and lengthy contact with the layers of the earth?s crust that they flow through, resulting in dissolution of minerals and metals from the rocks, and solution into the hot water. These aqueous solutions can be processed to recover minerals and metals. Some potential products include silica, zinc and lithium, along with other materials. Recovery of minerals and metals from geothermal brines can be viewed as ?solution mining by nature?, followed by application of known or new hydrometallurgical techniques for isolation and purification. This paper discusses the opportunities, the processes, the challenges, the current status, the economics and the potential for recovery of minerals and metals from geothermal brines.

Jan 1, 2006

By Fathi Habashi

Solid gas reactions of metallurgical importance can be classified into three groups: Physical processes, e.g., drying and sublimation Chemical processes which may be an addition or a thermal decomposition reaction Electrochemical processes which may be addition, oxidation-reduction, or displacement reactions. Examples are given and the role of the boundary layer is emphasized.

Jan 1, 1996

By Cong Wang, Kexin Jiao, Yongan Zhao, Haibin Zuo, Jianliang Zhang

The carbon composite brick is a new refractory used in blast furnace hearth and bottom. It caused wide attention due to its high thermal conductivity and low erosion by molten iron. In this paper, chemical constituents, SEM-EDS and X-ray diffraction were carried out in order to understand reaction mechanisms. A series of experiments of oxidation resistance characteristics were made. The oxidation mechanisms of carbon composite bricks in the presence of air were analyzed. According to the analysis on many experimental results, the oxidation process of carbon composite bricks under different temperatures were controlled by different mechanisms. In the condition of high temperature, SiO2 as oxidation product hindered the diffusion of O2, and reduced the oxidation loss of graphite in the internal.

Jan 1, 2015

By Bekir Karasu

Boron raw materials are amongst the most important natural sources for many industrial branches and their values become increasingly raised with the discovery of boron usage in many new technological fields. All the countries in the world are unfortunately not as lucky as Turkiye and USA where major boron deposits are mainly located. It is widely known fact that on one side, boron is very precious component with its technological importance, on the other; only its limited sources are available. Therefore, even its wastes have to be evaluated and regained. In the present work wastes of Etibor Kirka Borax Company of Turkiye were used in the production of opaque frits which was suitable for floor tile glazes. Standard and newly produced frit based glazes were applied on the pre-engobed floor tile bodies and single firing was employed. Final products were examined according to the certain standard tests and their microstructures were also investigated. All the results confirmed the evaluation of boron wastes in opaque floor tile glazes.

Jan 1, 2006

By Jin Liu

To improve value metals recovery, a new operating concept for the Inco flash furnace was investigated, in which the flash furnace coke addition practice would aim at establishing a reducing barrier on the surface of the molten bath. The descending partially oxidized sulfide mineral particles would reach the supernatant coke layer prior to the formation of slag. The key for success depends on the effectiveness of the coke layer to produce a sulfur deficient matte while maintaining furnace production capacity. The mechanism and rate of carbon reduction of the phases formed in the flash flame, i.e. sulfide (matte) and oxysulfide was investigated by means of crucible graphite reduction test work. The objective of these tests was to measure the rate of solid graphite reduction of matte, oxysulfide, slag, and matte+slag mixture at different temperatures. These tests were expected to permit understanding and explaining the reduction mechanism of each material by comparing the respective reaction rates, product reaction gas compositions, reduced material assays, and other relevant parameters. Direct visual inspection of the test crucibles would provide additional information.

Jan 1, 2006

Pyrometallmurgical reactors constitute a key processing component in the total primary and secondary resource cycle, being involved both in primary smelting, converting and extraction, as well as the reprocessing of scrap, from aluminum cans to end-of-life automobiles. To effectively control the overall resource cycle, one needs to take a systems modeling approach of the whole cycle, seeking to also understand the dynamic process behavior of the individual components of the cycle, and then especially the part that contributes most to the chemical conversion, namely the pyrometallurgical reactor. This paper highlights the role of pyrometallurgical thermodynamics, in the whole resource cycle and specifically places equilibrium thermochemistry in the context of process dynamics where large variable inventories are recycled or maintained within the system. This paper will therefore review the semi-empirical dynamic modeling tools, which are used to model complex systems with the specific goal of developing dynamic predictive models, which also include slag-alloy chemistry, towards controlling the recycling in a feed forward manner. To illustrate the primary processing side, high carbon ferrochrome will be presented as a brief case study. It also will show how the distributed nature of the chemistry of melts in the case of primary extraction, and secondary materials such as recycled end-of-life vehicles, have a significant impact on the process outcomes and model predictions. It is therefore argued that the fundamental thermodynamics and kinetics in metallurgical reactors playa final crucial role in modeling the closed material cycle, but only when it is used in conjunction with process systems theory based on reconciled data for parameter estimation and model calibration.

Jan 1, 2003

By Larry G. Stolarczyk

The development of geosteering technology for geothermal reservoirs is challenged by the integration of electrically small antennas in small-diameter metallic drill rods. To be useful, the antenna pattern must achieve sufficient back-lobe suppression, preferably with a forward-looking pattern. Forward-looking capability requires an antenna array with phase control. The phase-controlled antenna pattern enables imaging of geologic structures ahead of and surrounding the well bore. This paper describes the development of electric and magnetic dipole arrays for small-diameter drilling pipe.

Jan 1, 2006