Search Documents

Thermo Fisher Scientific is the worldÆs leading supplier of analysers for laboratories and process industries. The companyÆs X-ray fluorescence (XRF)-based slurry immersion probes were originally developed by the acquired Amdel Instrumentation. These analysers have found limited application within wet beneficiation plants for measurement of iron. The recent trend of renewed efforts to maximise recovery from existing resources and lower costs has increased industry interest in online analysis. In the mid-1990s the company developed online analysers (the light element slurry analyser û LESA) for slurry applications using the prompt gamma neutron activation analysis (PGNAA) method. The company has successfully installed LESA for the direct measurement of lighter impurity elements in Brazilian plants using flotation for rejection of silica. A case study is presented. The PGNAA technique has the unique ability to provide elemental analysis of bulk materials on a conveyor belt. The company released its eighth generation cross belt Omni analyser using PGNAA in 2007. Results from a recent project with sinter are presented. The Niton range of hand-held XRF analysers is also supplied by Thermo Fisher Scientific. These handy devices are finding widespread use in the mining industry to provide quick and easy analyses in exploration settings. In contrast to PGNAA this is a surface technique. A prototype for light element analysis is being tested for iron ore.

Jan 1, 2007

By S. J. Cook

Outstanding advances among the metals, marked the mineral production records for Canada during the first half of 1925. Production of metals and non-metals reached a total value of $90,347,698. as compared with $84,307,385. in the first half of 1924, an increase of 7.16 per cent. Metals and non-metals produced during the calendar year 1924 were valued at $17 4,202,537.; production during the first half of 1925 showed a sum equal to 51.86 per cent of this total. Advances among the metals were general. Gold rose to a new record. Lead advanced 62.41 per cent over the high mark attained in the first half of 1924. Nickel production was well maintained. Copper was up a million pounds. Silver showed increased values. Zinc followed the trend in lead to almost double the output recorded in the first half of 1924. Cobalt production continued to improve. Despite the loss due to the protracted strike in the Nova Scotia coal mines which reduced the output of coal in that province; during the six months ending June, to less than half the tonnage reported in the first six months of 1924, improved conditions throughout the rest of the non-metal mining field resulted in the production of non-metals during the half-year reaching a total value of $31,199,233. as compared with $36,844,286. in the first half of 1924; the loss in the value of coal output al one amounted to $5,723,873, while the decrease in the aggregate value of non-metals amounted to only $5,645,053.

Jan 1, 1925

By Manuel Montañez

Nexa Resources está comprometida con el desarrollo de las comunidades campesinas del entorno de sus operaciones. En ese contexto se inserta el proyecto descrito en este artículo, el cual está orientado a mejorar la calidad de vida de las comunidades del área de influencia de unidad minera Atacocha (Pasco). El proyecto analizado incluye el fortalecimiento de habilidades y valores locales, el desarrollo de capacidades para acceder al mercado y una adecuada transferencia tecnológica y técnica para un manejo sostenible de los recursos pecuarios (vicuñas).

Aug 30, 2020

By M. G. Maruma, L. A. Mampuru

"Mill liner wear is a major cost item in the mining industry and there is continuous research to prolong the life of the liners. Over the years it has become apparent that even though high-chromium white cast irons are highly efficient as abrasion-resistant materials, a combination of wear resistance and fracture strength remains difficult to achieve. Increasing the hardness of the high-chrome white cast iron (HCWCI), which improves the resistance to abrasion wear, is often accompanied by a deterioration in fracture strength. Operational conditions inside the mill require that the liner should be made of highly wear-resistant material with some fracture strength. Vanadium additions ranging from 0.2 to 3 wt% were made to HCWCI in an attempt to refine the microstructure. It was found that an increase in vanadium content promotes grain refinement. A content of 1.5-3 wt% gave the best results as measured by the maximum breaking strength.IntroductionOver the years it has become apparent that even though high-chromium white cast irons are highly efficient abrasion-resistant material, a combination of excellent wear resistance and fracture strength remains difficult to achieve. The exceptional wear resistance of highchromium white cast iron (HCWCI) is attributed to hard chromium carbides embedded in an austenitic/martensitic/pearlitic matrix. When the chromium contents exceed 12 wt%, interconnected MC3-type carbides of conventional cast irons are replaced by rodshaped and isolated M7C3 carbides (Powell, 1980), leading to an improvement in the impact toughness, ductility and fatigue resistance. However, the main M7C3 carbides in HCWCI are hard and brittle and can provide an easy path for crack propagation. This limits the applications of HCWCI, particularly in severe impact conditions. Most operations involving HCWCI are in crushing and grinding and the life of a part/liner is limited by its wear resistance. However, improving the wear resistance of HWCI comes at the cost of a significant reduction in fracture strength. Concerns about premature failure of HCWCI mill liners in the mining industries prompted a study to improve the wear resistance and mechanical properties of HCWCI."

Jan 1, 2016

By Masayuki Kudoh, Tohru Maruyama, Yohichi. Ito

When hypo-peritectic carbon steel is quenched during unidirectional solidification, the region of fine columnar grain is observed. It is classified into two coexisting phases. One is coexisting phases of liquid, delta and gamma in the upper part of the region, and the other is coexisting phases of delta and gamma in the lower part of the region. To form the coexisting part of the three phases means that solidification in this experiment proceeds in non-equilibrium state. The size of the narrow side of one fine columnar grain coincides with the arm spacing of a primary dendrite and this result is the same as the hyper-peritectic carbon steel. However, the boundary of the fine grain in the hypo-peritectic carbon steel is formed in different location from that of the hyper-peritectic carbon steel. The former is formed in the skeleton of the dendrite, while the latter is formed in the interspacing of the dendrite. The region of the fine grain changes suddenly to that of the coarse grain when the delta phase in the coexisting part of two phases disappears completely. Therefore, the delta phase in the hypo-peritectic carbon steel might prevent the growth of gamma grain. In order to recognize it, ferrite formers such as Mo, V and Ni are added in the sample. Then, the longitudinal length of the fine columnar grain extends in the sequence of the no addition, Mo, V and Nb.

Jan 1, 2000

By Chao Li, Qian Li, Yong-bin Yang, Kai Li, Qiang Xie, Yuan-yuan Zhu, Dong-ye Li, Qi-bing Tan

"The permeability of sintering mix is a vital technological property in sintering process. However, it can only be measured by off-line method on samples picked from the production. In order to acquire the properties of sintering mix accurately, on-line measuring of permeability is urgently required. Based on the reflection characteristics of bed permeability on pipe flowing parameters, a new method is presented in this paper for on-line measuring of sintering mix permeability. The measurement can be performed by blowing gas flow in the bed with the measuring pipe. Measuring results are obtained by picking the data on flowing rate and pressure in the pipe. The function of flowing rate to pressure may be certain for samples with the same permeability. Thus, the permeability was determined by contrasting this function to the result of off-line measuring, and the relative coefficient or R2 value was more than 99%.IntroductionThe permeability of sintering mix is a vital technological property in sintering process, which directly determines production and quality of sinter, or even determines whether the sinter production is carried out smoothly [1,3].The permeability have more obvious influence on vertical sintering speed, which is mainly related to air quantity passing through material bed. Under certain inducing capacity and negative pressure, the vertical sintering speed mainly depends on the permeability of sintering mix. Low permeability may make burning through point of sintering move back, and the sinter mix cannot be burnt through. High permeability may make burning through point of sintering move forward, improving production efficiency by increasing the speed of sintering machine [4] Good permeability means a small resistance of fan ,reduction of negative pressure of sintering machine, and full contact between air and sulfide, which can strengthen physical-chemical reaction during sintering process and increase desulphurization rate. In gas well through material layer process, gas-solid desulfurization reaction and gas-solid-liquid heat exchange are completed and hot gas through the combustion zone supplies the sintering process with heat. Finally uniform sintering of the material layer in height and width direction is achieved [5] While high permeability index leads to weak sinter strength, fast sintering speed, short residence time of high temperature region and little liquid phase. Moreover, liquid phase in the fast cooling process is too late to fully crystallize but forming glass phase which is harmful to sinter strength as well. Bad permeability means a big fan resistance and increase of negative pressure of sintering machine, which make the air pass through material layer difficultly. When air and mix contact difficultly, removal of sulfide reduces so that desulfurization is incomplete. Meanwhile, low caking efficiency, slow sintering speed and easily burnt sinter , reduce sinter output. Therefore appropriate permeability of sintering mix is the premise of stable burning through point and satisfactory sinter output and quality."

Jan 1, 2013

A parametric study was conducted to establish the optimum operating conditions for the column flotation of fine coal. The parameters examined in this investigation included collector and frother dosages, feed solids content, and the volumetric flow rates of feed slurry, air and wash water. Despite the wide range of conditions studied the experimental data were found to fall along single grade-recovery curves, just below the maximum separation predicted by the release analysis technique. The deviation of the parametric test data from the release curve was attributed to the nonselective entrainment of mineral matter associated with poor froth washing. The operating point on the characteristic recovery-grade curve was found to be primarily determined by feed rate and aeration rate.

Jan 1, 1992

By M. Abumiya, N. Onodera

Stabilization of arsenic via the precipitation of large-sized scorodite (FeAsO4·2H2O) particles usually involves the use of expensive autoclave systems operated under high temperature and pressure conditions. Alternatively, DOWA developed a novel scorodite synthesis process (DMSP®) wherein the Fe(II) ions in solution containing As(V) ions were oxidized by O2 gas under atmospheric pressure. In this process, crystalline scorodite particles were formed via the formation of a gel-like precursor containing Fe(II). Based on this concept, in this study, we have demonstrated the synthesis of scorodite particles by the addition of Fe(III)-containing solution to the experimental solution containing Fe(II) and As(V) ions, without the O2 gas oxidation process. Ferric sulfate (Fe2(SO4)3) was used as the source of Fe(III) ions. Results indicate the precipitation of scorodite particles, comparable to that of the O2 gas oxidation method.

Jan 1, 2014

By Z. Y. Lan

Bioleaching of marmatite with various mixed cultures of microorganisms was investigated. The experiments were carried out in shaking flasks with iron-free nutrient and the pulp density of 10% wt/vol at the temperature of 30?. The results show that zinc is preferentially leached before iron. The leaching rate of zinc with the mixed culture of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans is 62% in 18 days. The leaching rate of zinc with the mixed culture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans is nearly the same as that with the mixed culture of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans (45% versus 50%). SEM and EDX analysis of the leaching residues indicate that a solid product layer composed of iron sulfide, elemental sulfur and jarosite accumulates in the mineral surface and becomes a barrier to the dissolution of marmatite. The bioleaching of marmatite follows the shrinking core product layer model. When the product layer increases and becomes insoluble, the leaching rate is controlled by the diffusion through the product layer and slows down. When the product layer decreases or becomes a porous layer, the leaching rate is controlled by chemical reaction and enhanced dramatically.

Jan 1, 2014

By Richard D. Hagni

The United States is dependent upon foreign sources for more than 93% of its bauxite and alumina supply. Domestic production of bauxite, which comes from Alabama, Georgia and Arkansas, is limited to those bauxite ores containing less than about l ½ % iron. Bauxites with higher iron contents are generally not utilized because they cause problems in bauxite calcining and especially because they produce undesirable brick discoloration and cracking. In order to improve beneficiation and expand the utilization of high-iron or ferruginous bauxites, a mineralogical and textural study has been conducted on selected samples from the Eufaula, Alabama, bauxite district. Reflected light microscopic, petrographic, and X-ray techniques have shown that a variety of iron minerals are present, including hematite, goethite, lepidocrosite, siderite, pyrite, marcasite, and ilmenite. Although the iron minerals may be locally concentrated into concretions and pisolites, most occur as very fine grains that are disseminated and show a variety of intergrowths. Mineralogical and textural observations indicate that the fine-grained iron mineral grains may be amenable to high gradient magnetic separation.

Jan 1, 1981

By Arcy R., D&apos George

The Bureau of Mines has developed, on a laboratory scale, a superior Eluex-type circuit for eluting and recovering uranium from ion exchange resins. The improved circuit differs from conventional Eluex practice in that a stage of uranium solvent extraction is coupled with each stage of resin elution rather than the elution and solvent extraction operations being conducted separately. The new system reduces the number of stages, retention time, and resin inventory in the elution circuit to one-fourth or one-fifth that in existing circuits. The system is applicable to both resin-in-pulp and moving-bed-type ion exchange uranium recovery circuits.

Jan 1, 1969

By M. S. Celik

Salt-type minerals are usually floated with anionic and cationic collectors. Flotation of a number of systems has been reported to remarkably increase above the concentrations where surface precipitation of collector-metal salt is initiated. Some studies attribute this phenomenon to heterocoagulation of oppositely charged collector colloid and mineral particles. In this study, examples are given on boron minerals to demonstrate that the high flotation region occurs when particles, colloidal precipitates and bubbles acquire a similar charge which induces Van der Waals interactions resulting in hydrophobic bonding.

Jan 1, 1995

By Ronald A. Vary

This paper is one of a series prepared by the United States Bureau of Mines dealing with milling methods and costs. In view of the current revival of interest in gold mining, information dealing with practices and costs in the development of gold properties is apropos. Milling practice at a small gold property in the prospect stage is described where, with a small outlay for plant and equipment, development has been carried on for about 20 months on the proceeds of the mill operation with little additional expenditure. The paper shows about what may be expected as to costs at a small property operated under northern climatic conditions and with rigid economy throughout the plant.

Jan 1, 1931

By G. G. W. Thom, A. A. F. Schuldt

At The Steel Company of Canada, Limited, iron oxide dust from the basic oxygen open hearths is being collected by means of electrostatic precipitators. The utilization of this dust, which has been hampered by the presence of zinc and lead oxides and sulphur compounds, is made possible by direct reduction in a rotary kiln. The description of the dust collection system and the results of kiln tests are presented.

Jan 1, 1966

By J. J. Kellar

The near-infrared (NIR) (12,000-4,000 cm-1) region of the electromagnetic spectrum, between the mid-infrared and visible, has often been viewed by spectroscopists to be of limited utility. This is unfortunate, and recently the use of the NIR has increased greatly, primarily for the quantitative analysis of food and agricultural products. However, many other areas of application of NIR spectroscopy remain unexamined. In this paper a novel use of NIR in the area of flotation chemistry is demonstrated. Specifically, it is shown that NIR/Internal Reflection Spectroscopy (IRS) can be used to quantify collector adsorption reactions in-situ.

Jan 1, 1990

By D. E. Larson

The U. S. Bureau of Mines has developed a image analysis methodology to correlate the energy consumed during the grinding of an ore to the mineral liberation achieved. Energy consumption values are obtained using a laboratory-scale ball mill equipped with a torque sensor, and an automated image analyzer is used to determine the liberation present in ground products. By combining liberation information with energy consumption data an appraisal can be made of the energy required to liberate the mineral(s) of interest. Results of tests performed on a complex sulfide material determined the effects of grind duration on the liberation achieved and the energy efficiency.

Jan 1, 1995

By M Zoorabadi, B Hebblewhite, S Saydam, W Timms

Based on the cubic law, the hydraulic aperture of rock discontinuities has the most significant effect on the hydraulic conductivity of jointed rocks. The hydraulic aperture of rock discontinuities is a stress-dependant parameter and reduces with increasing applied stress. Furthermore, the rock stress increases with increasing depth. Therefore, hydraulic aperture is a depth-dependant parameter. In this paper, new empirical equations are introduced to calculate the hydraulic aperture of rock discontinuities at different depths. These equations were developed on the basis of back analysis of compiled packer tests from different actual cases. They provide the capability to calculate range of variation and average hydraulic aperture when the orientation of discontinuity and field stress tensor are given. Furthermore, it is possible to calculate the hydraulic aperture of rock discontinuities when its value is given for another depth. A hydraulic aperture of 7.7?µm was calculated by this method, comparing well with a reported site value of 8.3?µm for rock discontinuities at the Stripa mine project at a depth of 385?m. These new equations can be used by analytical or numerical methods to estimate the hydraulic conductivity of jointed rocks.CITATION:Zoorabadi, M, Saydam, S, Timms, W and Hebblewhite, B, 2014. New empirical equations to estimate the hydraulic aperture of rock discontinuities at different depths, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 375–380 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By Sungdon Kim, Chuljoo Kim, Joonsoo Kim, Hosung Yoon

"This study was performed to establish the optimum leaching condition through the experiments for the oxidized roasting followed by leaching of fluorocarbonate rare earth mineral (bastnasite) using sulfuric acid, and to establish the optimum condition for the recovery of cerium by ion- sieve method from the leached solution of bastnasite. The optimum conditions for the sulfuric acid leaching by the oxidizing roasting of bastnasite concentrates are that the roasting temperature is 550 -600 °C, the roasting time is 2 hrs, the concentration of sulfuric acid is 6N, the leaching temperature is S0°C and the leaching time is 3 hrs. At this time, the leaching yield of total rare earth oxides in the leaching of bastnasite concentrates is about 91%. When cerium is recovered by ion-sieve method from the solution obtained by the sulfuric acid leaching of the roasted bastnasite, the optimum conditions are that the TREO(total rare earth oxide) of leached solution is below 70 g/l, the flow rate of leached solution is 9.6 ml/min and the ratio of height to diameter of resin packed in column is above 9. In these conditions, the recovery of cerium of yield 85% and purity 96% is possible.IntroductionThe rare earths are generally called to Lanthanides, which are totally 17 elements including Scandium of atomic number 21 and Yttrium of atomic number 39 in addition to 1 S elements from Lanthanum of atomic number 57 to Lutetium of atomic number 71. Since the separation to each element is very difficult because of their similar chemical properties, the rare earths were used as the mixed rare earths and the mischmetal without separating to each element. However, the high purity rare earths are recently produced commercially to each element so that they are used as the materials for high tech. industry such as electric and electronic materials, catalysts, optical materials, special alloy and 8Uperconductive materials, and their consumption is rapidly increasing. Therefore, the purpose of this study is firstly to prepare leached solution by using the series of process of the oxidation-roasting and leaching by sulfuric acid. Next, second purpose is the separation and recovery of cerium by ion-sieve method."

Jan 1, 1998

By M. O. Pekguleryuz, D. S. Aydin

The high temperature oxidation and ignition resistance of Mg-(0-6) wt% Nd alloys have been investigated via isothermal and continuous heating experiments conducted in air atmosphere. Alloy composition is observed to be effective in low levels (~ 0.5 %) in the ignition temperature (Ti) of the alloys; the Ti of pure Mg increased from 630 °C to 770 °C with 0.5 wt% Nd addition. However, no noteworthy improvement was achieved with further additions up to 6 wt% Nd. The initial microstructure was observed to determine the oxide structure on the surface due to the differing oxidation behavior of the phases (a-Mg + Mg12Nd intermetallics). It has been found that the formation of a Nd-depleted region at the subsurface due to extensive Nd oxidation at the oxide/intermetallic interface lowers the protective ability of the oxide scale.

Jan 1, 2015

By V. V. Musaev, A. M. Klyushnikov, R. R. Galimov

"A study was made of chemical and material compositions of the oxidized gold-bearing ore of the Kochkovskoe deposit. It was demonstrated that examined ore consisted mainly of quartz, carbonate and feldspar with a gold content of 2.2 g/t and a silver content of 6.1 g/t. By means of agitation leaching tests it was founded that about 79-80 % of gold can be extracted from ore using cyanide leaching solutions. The achieved high-speed dissolution rate of gold was due to its presence in a finely dispersed state (less than 2.73 µm), which was confirmed by the research of Uralmekhanobr. It was proposed that the ore can be processed by heap leaching process using cyanide leach solutions. Technological studies on the modeling of the heap leaching process were initially carried out in percolators with a capacity of 5 kg on agglomerated ore. It was preliminary established that agglomeration should be carried out at a cement consumption of 12-16 kg/t, with the moisture content in pellets reaching up to 10-12 %. The best percolation leaching results can be obtained with ore crushed to the size of -20 mm. The maximum extraction of gold to the solution was 79-80 % while the L:S ratio reached 1.2-1.4:1.In cooperation with the research center of OJSC ""Berezovsky mine"" a semi-industrial heap leaching test was accomplished. The result of a test performed was an extraction of 78.5 % of Au and 21 % of Ag from ore to a pregnant solution. This extraction degree was achieved at a L:S ratio 0.9: 1. On the ground of results obtained, a technical regulation was developed for design of the heap leaching plant with the capacity of 500 thousand tons of ore per year.INTRODUCTION The ore of the Kochkovskoe deposit represents an important reserve of gold in the Zabaikal region. Of the upmost interest are oxidized ores, the processing of which can be carried out by heap leaching (HL) with cyanide solutions. The purpose of this work was to study the composition and to develop a technology for heap leaching of oxidized ore."

Jan 1, 2018