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By Antônio Peres, Rogério Guimaraes, Lauro Takata, Harold Wyslouzil

"Serrana’s concentrator, in Araxii, has capacity of producing approximately 800,000 tomes of phosphate rock per year, with a P205 grade of 36%, from ores grading between 13% and 14% P205. The annual mining rate is around 3.5 Mt and the apatite is concentrated according to the following sequence: crushing, grinding, desliming, flotation and low and high intensity magnetic separations.Two industrial flotation columns (3.0 m x 4.5 m x 14.5 m) were commissioned in 1993 as a replacement for circuits of barite and apatite fines flotation. In 1994, four additional flotation columns of the same dimensions were put into operation, replacing 42 Wemco mechanical cells (300 ft3 each), in the barite pre-flotation, coarse apatite (two columns) and tailings regrind flotation Circuits. Overall, 66 mechanical cells (300 ft3 each) were replaced by only six flotation columns, designed by Cominco Engineering Services Ltd - CESL.The present paper describes the stages of process development, pilot plant testwork and implementation of the industrial project, highlighting the most relevant aspects of each of them. The results achieved are related to improvements in flotation selectivity, gains in P205 recovery and better process control, resulting in better quality products and lower production costs. Other benefits included a decrease in flotation reagents, electrical energy and maintenance materials consumption. These factors contributed to a significant decrease in the cost of phosphate rock production at Serrana, in Araxa - M G."

Jan 1, 1999

An integrated palynological and sedimentological investigation of four wells from the eastern margin of the Gippsland Basin has resulted in a scheme for classification of palynofacies in this area. Thirteen different palynofacies assemblages are recognised and assigned to particular environments based on the enclosing sediments, which range from alluvial, through coastal barrier to continental shelf environments. Close correlation is observed between the interpreted energy regime of the palynofacies assemblage, and that of the enclosing sediments. Assemblages characterised as reworking surfaces can be correlated with unconformity producing events (ie tectonic activity associated with the opening of the Tasman Sea), and some of the minor eustatic sea level Changes.

Jan 1, 1992

When the 2008 Olympic Games begin in Beijing, China is September it will not only mark the end of the journey for the Olympic torch and the thou-sands of participating athletes, but the games will also mark the culmination of a massive amount of construction in the city. On display for the world to see will be 31 new and refurbished venues including the 91,000-seat National Stadium called the ?Bird?s Nest? and the aquatics center, called the Water Cube. What will not be featured as prominently on the television cameras broadcasting the games around the world will be the network of tunnels built beneath the city. But that infrastructure of rail lines will be of critical importance to the games. While preparing to host the world, China added a subway tunnel that will include four stops in the Olympic Park. The 4.4-km (2.7-mile) subway line that runs through the complex of stadiums, gymnasiums and parks began trial operations in June. Prior to the opening of that line, Beijing's No. 5 subway line, which runs through the heart of the city from north to south, opened in October. That 27.6-km (17-mile) line took nearly five years to build and includes 23

Jan 1, 2008

By Prosser A. P

The conditions under which vanadium is rendered insoluble by silica in the alkali-roast process have been investigated starting with both slag and reagent-grade materials. The inert phase is a glass formed slowlyfrom soluble NaV03 produced at lower temperatures. It contains approximately 30 per cent V in a partly reduced state; iron is not a principal component. Some of the vanadium in the inert phase is slowly returned to a soluble form by heating in an oxidizing atmosphere below the temperature at which the glass is formed (750°C). As the reaction leading to the required, soluble form of vanadium is also slow between 600 and 750° optimization and control of the temperature profile and atmosphere in the furnace, and the residence time of the solids, are necessary to ensure high vanadium extraction during subsequent leaching.

Jan 1, 1976

By Raymond W. Henn

The 32nd annual short course ?Grouting Fundamentals and Current Practice? was held at the Colorado School of Mines, June 13-17, 2011. The field demonstration portion of the course was conducted June 16 at Baski Inc.?s yard in Denver, CO. The full-scale field demonstration presents many types of drilling and grouting equipment in operation as well as numerous grouting methods per-formed under various field conditions. As part of the field demonstration, the class was shown the proportioning, mixing, testing and injection of various cement grout mixes into sand columns under controlled and recorded conditions. These sand column demonstrations have been conducted under controlled and measured conditions each year since 1999 as part of the short course. The sand column demonstrations were conducted prior to 1999, but with less quality control and minimal record keeping of the proportioning, mixing, testing, injection pressures and the final permeation results.

Jan 1, 2011

An examination is made of some of the consequences of a magmatic gas phase developed during a late stage of differentiation of an acidic magma. Elements possessing halides with high partial pressures (Sn, Mo, W) may be removed from the magma by distillation into gas bubbles in the manner suggested by Fenner (1933). The common chalcophile elements are not affected by this mechanism, but form sulphides which may become attached to rising gas bubbles by one of three distinct mechanisms. The gas bubbles may then carry the sulphides upwards and concentrate them in some favourable locus, giving rise to an ore-forming fluid. The process would operate selectively upon different sulphides and is capable of providing an explanation of the paragenetic succession observed in ore deposits as well as other important geological criteria of ore genesis.INTRODUCTIONThere is a widespread belief among contemporary geologists that a large and important class of ore deposits is genetically related in some way·to acidic igneous rocks. This class includes the tin-tungsten-molybdenum-bismuth type of mineralization as well as a variety of sulphide deposits.A basic problem confronting explanation of the genesis of these deposits is the manner in which trace elements which were originally widely dispersed in granitic magmas were segregated therefrom and concentrated into economic mineral deposits.The principles underlying the formation of one group of minerals deposits (pegmatites) related to granitic magmas ate reasonably well understood, largely due to the labours of Goldschmidt and his school. However, many geologists have noted that there appears to be some sort of fundamental discontinuity between pegmatite formation and the origin of the more common hypogene ores, particularly sulphides.Accordingly it has been suggested that these ores...

Jan 1, 1956

By Wei Sun, Ruolin Wang, Jianjun Wang, Xiaodong Li, Honghu Tang, Yuehua Hu, Anh V. Nguyen, Haisheng Han, Kefeng Chen, Zhao Wei

It is difficult to separate scheelite especially from fluorite with fatty acid collectors because the adsorption mechanism of these collectors occurs through chemisorption of the oleate ion onto the mineral surface. A simplified flotation process using Pb-BHA complexes was developed to replace the energy-inefficient Petrov’s process of using a fatty acid, increasing the recovery of scheelite and reducing the cost. The relationship between surface chemical properties (crystal chemistry, solubility, and Zeta potential) of minerals and flotation by using a fatty acid or Pb-BHA complexes was studied in detail to provide new insights into the selective separation mechanism. The results indicate that the scheelite surface exposes more O atoms than Ca and that they are negatively charged due to the anisometric dissolution of Ca and WO4, which provides the possibility for separation using selective interfacial reaction. The FTIR and Zeta potential results indicate that both chemical and electrostatic adsorption play an important role in the adsorption of Pb-BHA complexes on the scheelite surface. The XPS results of the atomic composition and binding energies confirmed the presence of the adsorbed Pb-BHA complexes and that O and Ca may be the active adsorption sites. Therefore, scheelite was able to be collected by forming either a Ca-O-Pbcollector or W-O-Pb-collector (BHA). However, fluorite was only able to be collected by a fatty acid collector and colloidal [H2SiO3]n -, and a high temperature was needed improve the selective desorption of the adsorbed fatty acid collector by forming Ca-[H2SiO3]n - on the fluorite surface, resulting in serious problems in industry. However, the Pb-BHA complexes significantly contribute to improving the recovery of scheelite minerals, simplifying the flotation process, and circulation of the residual reagents and water. The new process has been applied in Shizhuyuan Mine, and improved the recovery by almost 10%.

Jan 1, 2018

By T. Veneroso

Comminution is the process by which rock or ore is reduced to a size where the liberation of the minerals is maximized without changing the chemical or physical properties of the rock. Comminution accounts for about 50% of all energy that mines use (Klein et al., 2018). Growing demands from stakeholders and shareholders for sustainable development and CO2 reduction will increase the need for energy-efficient comminution. Ores with different mineralogical characteristics, textures, strengths, apparent stiffness, and mass-specific fracture energies need to be processed with a specific, new, and efficient comminution technology to increase the production and profitability of mining companies. The adoption of crusher wear parts built with new materials, such as non-Hadfield manganese steel or synthetic materials or traditional manganese with wear-resistant components, could improve the efficiency of the crushers, reduce downtime, increase production, improve the desired P80 (the aperture through which 80% of the product will pass) product size distribution, and enhance mine safety.

Feb 1, 2023

By Paul H. Atkinson

"Sampling in the mineral processing industry has always been a subject which has received considerable discussion. There have been many volumes written on theory, techniques and practical application of sampling. However, until recently, the companies were not completely aware of the potential savings available with properly designed sampling systems both to assist in pieces: control and final product values.Definition In our discussion today, we will define sampling as the operation of removing a part, convenient in quantity for analysis, from a whole, which is of much greater hulk, and removing it in such a way that the proportion and distribution of the quality to be tested, i.e. size of particle, moisture content, specific gravity content, mineral and chemical composition, are the same in both the sample and the whole.Application It has been well established that undetected errors can result in large economic losses, thus most firms depend upon some type of sampling and sample analysis as a control in their continuous processing of materials. Despite the large investment in facilities and personnel the ""analysis"" of a sample can be no more accurate or reliable than the sample on which it is being based. The importance of sampling is recognized by a great many but it is appreciated by only a few, largely because it is sometimes one of the items which is taken for granted."

Jan 1, 1976

By S. J. Thiele, T. Newton, W. Magalhäes, T. Takayama, J. Welsh

Companhia Paraibuna de Metais (CPM) is presently pursuing a zinc production expansion project. Besides increasing production, the goal of the project is to address existing problems while providing a platform for a proposed twofold increase in production in 2003/2004. Therefore, the current expansion strategy was formulated to address present and future requirements. Computer simulation modeling and full scale plant testing are being used to generate data to optimize the operating conditions and to perform a sensitivity analysis. The initial phase of the project, which will boost CPM's capacity to 86,000 t/y of marketable zinc, is to be completed in September 2000.

Jan 1, 2000

By J. C. Schneider, G. Van Weert

Hydrochem Developments Ltd. has developed and put into full scale operation a novel type of vertical flotation column incorporating a multiplicity of mechanically agitated stages. Characteristics of this flotation column include a low height to diameter ratio, high upgrading factors and the possibility of modifying geometry and operation to specific flotation requirements. A commercial unit is currently handling up to 100 tpd rougher concentrate at Dickenson Mines Limited, Balmertown, Ontario. Design parameters and plant performance will be discussed.

Jan 1, 1988

By S. J. Stokowski

Abstract An extensive drilling and laboratory testing program indicates that a construction aggregate resource is present within the Oligocene Sombrerito Formation limestone, southwestern Dominican Republic. The first part of the testing program included the collection, photographing and geologic logging of diamond drill cores to allow lithologic subdivision of the strata into potential quarry layers. The primary lithostratigraphic units are: I- (youngest) approximately 10 m of white, dense marine limestone II-approximately 5 m of white, interbedded dense and chalky marine limestone III-more than 2 m of tan, chalky, calcitic dolomite. Unit I is often altered by lateritic weathering and/or dolomitization. Unit II is often altered by dolomitization. The cores were individually crushed by quarry layer into coarse and fine aggregate sizes for chemical and physical analyses: specific gravity and absorption, MgSO4 soundness, sand equivalent, Atterberg limits of the minus #40 mesh fraction, and LA degradation. The unaltered portion of Unit I is suitable for all construction aggregate uses. Unit II is best suited for crushed stone base. Each of the non-weathered units decreases in coarse-aggregate yield and quality with depth and diagenetic dolomitization. Dolomitization typically causes about 5% lower yield of coarse aggregate, a sand equivalent of about 20 units below the original value an increase in absorption of about 3%, an increase in the LA of up to 13%, and a decrease in the average five-cycle MgSO4 soundness of about 17%.

Jan 1, 1991

By I. Alp

Application of magnetic separation was investigated for the enrichment of colemanite ores by removing the magnetic gangue fraction. The detailed XRD analysis of the ore has indicated that the gangue fraction is composed predominantly of the iron-bearing silicates such as smectite and, to a lesser extent, illite. Magnetic susceptibility measurements of the colemanite and gangue samples have proved that colemanite is diamagnetic in character whereas gangue fraction is weakly paramagnetic to allow the removal of this fraction by magnetic separation. Magnetic separation of the crushed and sized ore samples (-5 mm +75 µm) was performed using a high intensity permanent magnetic separator. Under the test conditions a colemanite concentrate (41.29 wt.% B2O3) was found to be produced from the crushed ore (30.76 wt.% B2O3) at a recovery of 96.76%. These findings suggest that magnetic separation has great potential as an alternative process for the production of a concentrate of commercially sufficient grade.

Jan 1, 2009

By J. T. Furey

"A pilot plant study was conducted to evaluate the performance of column flotation in the recovery of gold from a gold/tellurides bearing sulphide ore, and to compare the performance of column flotation to conventional ""mechanically agitated"" flotation.Tests were conducted in a 60 liter glass column with ground flotation feed split from a concurrently operating conventional pilot plant, thus permitting direct comparison between the two processes. During the test program, the effects of wash water rate, gas holdup, froth depth, residence time and flow bias were examined in detail.The ore had an average ""as tested"" feed grade of about 5 g/t gold and 1 % sulphur, with the gold occurring primarily as inclusions of montbragite (Au2Te3) in pyrite, with minor amounts of native gold. Conventional flotation using 60 minutes residence time across four roughing stages recovered about 97% of the gold into concentrates grading about 50 g/t Au. A single stage of column flotation roughing using 25 minutes residence time matched the conventional circuit recovery of 97%, but produced grades of+ 150 g/t Au. INTRODUCTIONColumn flotation is the most significant innovation that has occurred in the mineral processing industry in recent years and has become an important alternative to mechanical flotation. Column flotation has been most widely accepted and applied in cleaning service where it has frequently proven to be superior to mechanically agitated flotation. Roughing in columns has not been ignored, but early testing indicated that columns may not be capable of achieving adequate recovery and, to date, columns have not been seen as serious competitors for mechanical roughers."

Jan 1, 1990

By Donald J. Knight

HEAT Treatment at 1500' F of a mild steel containing 0.1 pct C, in an atmosphere which is oxidizing to both carbon and iron, results in the progressive oxidation of the metal surface with little or no change in the carbon content of the underlying metal. Further heat treatment of the scaled metal in either a neutral atmosphere or in a vacuum may or may not result in the decarburization of the metal depending upon the physical nature of the scale. It is apparent that if a continuous layer of oxide is present on the steel surface, the reaction OScale + Cmetal Cogas cannot progress since the SO formed gas would be unable to leave the oxide/metal interface. Thus, in order for the reaction to progress, the oxide must be cracked or porous. Vacuum heat treatment at 1500" F of samples with a thick continuous oxide scale showed no decarburization of the steel. However, when cracks were introduced mechanically into the scale prior to the vacuum heat treatment notable decarburization of the metal resulted and a structure as shown by Fig. 1 obtained, i.e., reduction of the crack walls to ferrite. With reference to the diagram of Fig. 2, it would appear that a mechanism of the following type takes place. Carbon atoms arriving at an oxide/metal/void interface, such as 'A', Fig. 2(a), can combine with oxygen atoms from the scale and leave the reaction site as Cogas thereby reducing the oxide to metal. On a greatly magnified scale, Fig. 2(b),this will appear as a ferrite projection along the crack wall. Carbon atoms entering this projection can react with oxygen atoms at point 'C', which is a new interface, and so on leading to a progressive growth of the ferrite along the crack wall and to the surface, Figs. 2 (c) and 1. It would appear that the only means by which thickening of the ferrite film can take place is by a diffusion of oxygen through the ferrite film to react with carbon at the newly formed ferrite/ void interface. Since the diffusion rate of carbon is reportedly much greater than that of oxygen, and since there is a low probability factor of oxygen and carbon atoms arriving simultaneously at the same site on the ferritehoid interface, there will be a tendency for more rapid lengthening than thickening of the ferrite layer, as is observed.

Jan 1, 1962

By Elimame Elaloui, Kais Elghniji, Constantin Virlan, Aurel Pui, Chaima Ouled Amor

Separation and identification of minerals composing the Tunisian silica sands have been conducted by acid etching and hot filtration/sedimentation (HFS) without affecting the quartz component. It was found that the hot acid etching process is an effective method to separate quartz and clay minerals in the silica sand. The SEM micrographs of the silica sand show rough surface and some cracks with irregular shapes. The surface becomes clean and smooth after acid etching process. After chemical dissolution, the clay minerals were recovered by hot filtration following by sedimentation at low temperature. FT-IR, EDS maps, and secondary electron (SE) analyses of separated clay minerals reveal the presence of Fe2O3, montmorillonite, and kaolinite minerals. The LIBS analysis of clay minerals shows the presence of Al, Fe, Ca, Al, and Mg. The sequential etching process can be introduced in the purification methods as an effective way to separate quartz from clay minerals.

Jul 29, 2020

By Z. A. Md-Nor

Risk management is an established loss-control methodology that has been applied successfully in many industries. Recently, interest in this structured approach has grown in the mining industry. The main objective of this research was to develop a risk-assessment process, which is a part of risk management, that can be used by the U.S. mining industry to more thoroughly characterize risks associated with haul truck-related fatalities. The assessment is based on historical data obtained from the U.S. Mine Safety and Health Administration (MSHA) investigation reports, which includes 113 fatal incidents that occurred from 1995 through 2006. The risk-assessment process used in this research involves the following basic steps: identification of the risks, risk analysis and risk evaluation. The preliminary hazard assessment (PHA) method is used in identifying and quantifying risks. Risk levels are then developed using a pre-established risk matrix that ranks them according to probability and severity. The resulting assigned risk value can then be used to prioritize control strategies. This paper is a part of a detailed study on risk assessment for equipment-related fatalities in mining sponsored by the Western U.S. Mining Safety and Health Training and Translation Center.

Jan 1, 2008

By H. J. Uananisa, M. J. Papo, C. W. Siyasiya, W. E. Stumpf

"SynopsisThe need to reduce weight while maintaining good mechanical properties in materials used in the automotive industry has over the years seen an increased exploitation of various steels to meet this new demand. In line with this development, the ferritic stainless steel family has seen a wide application in this industry, with the AISI 436 type increasingly being used for automotive trims and mufflers for exhaust systems, as well as a significant part of this steel’s application being for the manufacture of wheel nuts and wheel nut caps in trucks, mainly through the deep drawing process. However, there have been reports of some poor surface roughening of this material during deep drawing, with tearing and/or cracking also reported in some instances. This has been suspected to possibly be associated with some local differences in localized mechanical properties between grains and grain clusters of the rolled and annealed material.In order to investigate the poor surface roughness exhibited by AISI 436 ferritic stainless steel (FSS) during deep-drawing, Lankford values (R-mean and ?r), grain size, and microtextures of various sheet samples from this steel were studied. The chemical composition range for the samples was 0.013–0.017% C, 17–17.4% Cr, 0.9–1% Mo, and 0.4–0.5% Nb. The steels were subjected to various hot and cold rolling processing routes i.e. involving industrial direct rolling (DR) or intermediate annealing rolling (IR), and the drawability and final surface qualities of the steels were compared. It was found that the DR route gave an average R-mean and ?r value of 1.9 and -1.4 respectively, while the IR route yielded an average Rmean and ?r value of 1.6 and 0.52 respectively. The high ?r value for the DR processing route had a substantial adverse effect on the drawability. IR samples exhibited a smoother surface finish on visual inspection, while clear flow lines were visible on the DR samples, despite the fact that DR is the preferred industrial processing route due to the reduced production costs it offers. This observation was also confirmed through SEM examinations. The difference in the surface quality was attributed to microtexture. However, the mechanism responsible for this difference still needs to be identified."

Jan 1, 2015

By Jeane Hull

Jan 1, 2009

A Sun SPARCstation based computer network is utilised to store and process mining data at the Macraes Gold Mine. Techbase and Medsystem software running on the SunOS unix platform is used to generate all data plans, sections and other design data required on a daily basis to run the mining operation. The Macraes site is regarded as a fully integrated site where all geological, grade control, exploration, orebody modelling, resource estimation, pit optimisation and mine design is undertaken on site by MacraesÆ professional staff. The methodologies employed are regarded as æstate-of-the-artÆ where computerisation allows the rapid and efficient evaluation of large quantities of mining data by a handful of professional personnel. Ore reserves are estimated using an indicator kriging method and roving cone pit optimisation, a complex process that would not have been achievable in pre-computing days.

Jan 1, 1992