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By V. F. Petrov

Cyanide is widely used gold lixiviant for hydrometallurgical processes. The resulting tails contain complex toxic compounds. With reference to this, the protection of the environment should be the major issue. A complete detoxification of cyanides before disposal, a partial detoxification to the allowable concentrations and a disposal of tails at a polygon followed by the detoxification of excess water into the environment are offered as an environmentally friendly way of disposal. However, a complete detoxification of the cyanidation tails does not give the required results due to the presence of toxic compounds, cyanides and thiocyanates in tailings ponds. This is due to adsorption-desorption process occurring between solid and liquid phases. A partial detoxification is used to down cyanide to the allowable concentrations, which are safe to the environment. The storage of tails without detoxification is mainly used at low concentrations of toxic compounds in the disposed tails. With reference to this, water recycling is practiced by Russian plants in order to reduce as much as possible or almost eliminate toxic effluents into the environment. Fresh water is applied if necessary and to make up for water losses, with 8-12% of total water supply. This allows for the stability of water balance and the decrease of consumption of the reagents applied. The conditioning technologies of water recycling followed by regeneration of free cyanide and metals recovery as saleable concentrates are specially developed due to adverse impact of water recycling on gold recovery processes due to high concentration of base metals (copper). These technologies are also profitable. In order to detoxify cyanide in the tails for tailings dam, effective and inexpensive technologies involving a seasonal use of detoxified reagents were developed. For example, a technology with aldehydes use which is applied by a series of operations. Effluents disposed to the environment are detoxified using chlorination followed by almost a complete destruction of toxic cyanides and thiocyanates. Before disposal, chlorinated water is settled to precipitate the resulting hydroxides of metals and complete chemical reactions such as a full decomposition of hypochlorite ions. In order to protect ground water, watertight screens from local water-resistant materials are used. The samples of these materials were previously tested and chosen according to their maximum ability to adsorb toxic compounds in the tailings pond. If local water-resistant materials are not available, whole welded impermeable polymer screens are used. The options mentioned allow the storage of cyanidation tails in accordance with national ecological standards. Keywords: cyaninides, thiocyanates, wastes, environmental safety, recycled water-supply, detoxification, storage

Sep 1, 2012

By J. Palarski

Hard coal, mined in Silesia Region as well as in the eastern part of Poland, is a key national resource. In Polish underground coal industry, modern mining technologies have been successfully tested and used in the last 50 years. More than 98% of the coal produced underground is extracted by longwall mining method. Current underground coal mining expands into increasing depths. The use of conventional coal extraction methods ? room and pillar and longwall with caving - is becoming increasingly difficult. The coal mining is modifying existing methods and is testing innovative technologies. Backfill is an important component of modern underground mining operations. In Polish underground mines, backfill is recognized as an integral component for extraction of coal from greater depths in a densely populated environment. The modifying and innovative methods require the use of backfill or grouting of caving to provide structural support in underground excavations and to ensure that the mining operations are safe. Depending on the geological structure, mining conditions and environmental requirements there are several variations of longwall methods used in underground coal mining in Poland, in particular: longwall with caving, longwall with backfill, longwall with grouting of caving area. This paper will discuss the different components of an effective longwall production and filling process of caving area. The paper will give a overview of the current application of backfill technology, focusing on Polish coal mining operations. This paper will also briefly describe how backfill contributes to an innovative method ? underground coal gasification. The paper discusses specific requirements for fill materials and the technology of backfilling for underground coal gasification (UCG) operations and problems of implementation and correlation of backfill parameters with other processes that occur during thermal processing of coal.

Aug 1, 2013

By C. Jay Hodgson, P. J. MacGeehan

"The gold ore zones of the Campbell and Dickenson mines occur within a km-wide, 2 km-long zone of highly altered and anomalously fissile and deformed volcanic and subvolcanic intrusive rocks, cut by a series of mainly post-deformation mafic and quartz-feldspar porphyry felsic dykes.Three main periods of gold ore-forming hydrothermal activity are recognized. In the first, the mine rocks were extensively altered and gold and arsenic enriched; syn-volcanic auriferous veinlet and low-grade chemical sedimentary ores were deposited in what was a major discharge zone of a submarine hydrothermal system. The chemical sedimentary ores are closely associated spatially and temporally with domal rhyolitic extrusions. Because of its mechanical and chemical properties, this synvolcanic alteration zone became the locus of later deformation, and the site of the generation of auriferous hydrothermal solutions, perhaps by pressure solution processes at depth. These solutions deposited, synchronously with deformation and metamorphism, the second and most economically important type of ore zones in the mine: large foliation-parallel and foliation-oblique banded carbonate- 'chert' Rssure-filling veins.In the third and final mineralizing event, high-grade, pipeshaped zones of siliceous replacement-type mineralization, and quartz-arsenopyrite-gold veins, were superimposed on the previous mineralization types after most of the deformation, but before the emplacement of the late dykes. The source of heat and also possibly the fluids for the third mineralizing period may have been the dyke-forming igneous activity. The textures and mineralogy of the banded carbonate- 'chert' veins suggest a near-surface (<3 km) environment of deposition, but their relationship to the fabric of their host rocks indicates they were emplaced in an environment, presumably at considerable depth (5-10 km?), in which the rocks were undergoing intense penetrative deformation. This anomaly is unresolved."

Jan 1, 1982

By Mike Perkins

The Summitville Au-Ag-Cu district in the southeastern part of the San Juan volcanic field has been a major gold producer in Colorado. Mineralization is hosted by the composite South Mountain quartz latite porphyry volcanic dome, which is believed to have been localized by the intersection of the northwest margin of the Platoro-Summitville caldera complex and the northwest-trending Platoro fracture zone. K-Ar age dates indicate that alteration and mineralization were nearly contemporaneous with emplacement of the dome at 23-20 m.y. ago, 6-7 m.y. after collapse of the Platoroo-Summitville caldera complex. The dome consists of at least four major phases including strongly altered quartz latite porphyry; a late-mineral, coarse-grained sanidine quartz latite porphyry; and postmineral quartz latite dikes. The dome was emplaced into intracaldera rhyodacite and andesite. Gold-silver-copper mineralization is concentrated near the top of the dome and is associated with pods, pipes and steeply dipping tabular zones of silicification and advanced argillic alteration. Alteration is zoned outwards from the center of mineralization through argillically and propylitically altered rocks, and is largely confined to the area of the dome. Trace element geochemical patterns for the deposit indicate a central zone of anomalous As-Au-Pb-Ag and low Mn within an exterior zone of anomalous Ag-Au-Pb-Hg and high Mn. The chief ore mineral is native gold which is associated with goethitic iron oxide in the oxide zone. In the sulfide zone, native gold is associated with copper sulfide-sulfosalt mineralization. A genetic model for the Summitville deposit is based on recent models of modern geothermal systems, with which it shows similarities in alteration, ore mineralogy, zoning, and structural patterns.

Jan 1, 2013

By Peter Halbach

Within the frame of the German-Indonesian cooperative Bandamin research project two short cruises (7 station days each) were carried out which led to the Flores-Banda basin located north of the active volcanic arc. This basin is part of a large island-arc subduction-collision system resulting from a complex plate tectonic situation in which three major plates collide with each other. The eastern part of the Sunda-Banda convergent margin also includes the transition from subduction of oceanic lithosphere to collision of the Australian continental crust with the arc. This transitional part is cut and displaced by various large obliquely striking fault systems. Thus, the south eastern and eastern arc segments represent geological conditions which are suitable for the development of hydrothermal convection and potential mineral precipitation. Our study area lies north of the transitional section between Flores and Wetar. We started with a high-resolution bathymetric mapping of 240 km2 in a region some 36 km north of the island of Lomblen. A small submarine neovolcanic ridge was discovered striking approximately NW-SE and consisting of several submarine volcanic structures. In the northwest of the study area, the active subaerial Komba Volcano (Batu Tara) marks the youngest continuation of the ridge system examined. From the ridge we collected fresh and hydrothermally altered volcanics with disseminated sulfides (pyrite, pyrrhotite, markasite, and chalcopyrite), together with ferrugenous gossans.

Jan 1, 2004

In the Ngakuru area, zeolite deposits occur in late Quaternary lake sediments and ignimbrites. The deposits are associated with sinters, hydrothermal eruption breccias, and quartz-adularia altered fault breccias: all indicators of a shallow epithermal environment. Several of the deposits are adjacent to epithermal gold prospects. Zeolites are most abundant in lacustrine tuffs of the Ngakuru Formation, a 100-300 m thick sequence of siltstone, tuff, diatomite, sandstone and conglomerate. The formation overlies the Ohakuri Ignimbrite dated at c. 270 Ka, and is unconformably overlain by alluvial sands and gravels which are younger than 20 Ka. Individual zeolite deposits contain 30-80 per cent zeolite over a thickness of up to 45 m in thinly stratified tuff beds. The tuff beds are locally overlain by diatomite. The tuffs are composed mainly of glass shards and pumice clasts, with minor volcanic plagioclase, quartz and biotite crystals. Glass shards in the tuffs are replaced by the silica-rich zeolites mordenite and clinoptilolite. Amorphous silica (opal A), opal-CT, K-feldspar and smectite are also present. The distribution of the Ngakuru Formation is controlled by northeast trending normal faults, which separate it into the Ngakuru and Guthrie grabens. A silicified (quartz-adularia altered) hydrothermal breccia along one of the fault zones suggests that the faults acted as feeders for heated water that caused the deposition of the zeolite minerals. Some of the zeolite deposits are adjacent to sinters and hydrothermal eruption breccias. The location of the sinter about 20 m above one deposit indicates that the zeolites were formed at a depth of 20 to 70 m below the paleosurface. The hydrothermal eruption breccias contain clasts of altered ignimbrite, which contain geochemically anomalous gold and silver values. By analogy with their occurrence in active geothermal systems in the Taupo Volcanic Zone, mordenite and clinoptilolite in the Ngakuru deposits probably formed at temperatures of 60-150oC from near-neutral pH waters as a result of interaction with glass-rich tuff beds. The Ngakuru zeolite deposits are therefore interpreted as shallow hydrothermal alteration zones within larger epithermal gold-bearing systems.

Jan 1, 2002

By D. R. Spears

The U.S. Bureau of Mines has had an ongoing interest in developing new reagent schemes for floating Stillwater, MT, chromite ore. Previous reagent schemes have been unsuccessful in achieving complete separation, primarily because little is known about the surface chemistry of the minerals in this ore. In order to design a rational reagent scheme, a study of the binding of various functional groups (R = -H, -OH, -CO2H, -NH2) on the two components (chromite and forsterite) of the Stillwater chromite was undertaken. Electron Paramagnetic Resonance (EPR) Spectroscopy was used to determine the adsorption isotherm, from a cyclohexane solution, of spin-probes which contained the functional group of interest. This was complemented by studies of the saturation surface coverage of the spin probe on the two minerals. In each case, more sites existed on chromite than forsterite; however, the forsterite sites were more strongly binding for each functional group. The results are discussed in terms of their implications for flotation.

Jan 1, 1994

By B. J. Arnold

During the past three years, coal samples covering a range of coal rank, ash content, size consist, grindability, and moisture content have been tested for their flow properties using a triaxial shear tester that measures the unconfined yield strength in a compressed sample of coal. The ratio of this unconfined yield strength to the sample bulk density is part of the equation used by handling system manufacturers to calculate the critical arching or critical ratholing diameter needed to ensure that coal will flow from bunkers or bins. This ratio also serves as an index to compare the flow tested. To test the applicability of the index to predicting problems with coal flow, a series of tests were conducted at CO Inc.&apos;s Coal Quality Development Center (CQDC) in Homer City, Pennsylvania. Tests covering ranges in size consist, moisture content, and ash content were conducted by first filling a small two-ton bin with coal and then emptying the bin at a pre-set discharge rate. The actual discharge rate from the bin under the various conditions tested was measured. Samples of the coal discharging from the bin were collected. One sample was analyzed for ash, moisture, and size consist; another sample was sent to the Iowa state University for trivial shear tests (supplying an index measurement). Actual flowability results from the bin were then compared to the measured index to determine the applicability of the handleability index in actually predicting coal flow problems. This paper describes the correlation between handleability index and bin flow and explains the next stages of the project.

Jan 1, 1992

By M. Yavuz

Equipment selection in mining operations is an important issue, and also difficult to solve in multiple criteria environments. The paper in question has aimed to develop computer software for solving equipment selection problems in mining. In their paper, Basçetin et al. have analysed two case study problems related to open pit and underground mining method selection. By using Yager?s method1, the authors have selected 18 different criteria in the first case study and 21 criteria in the second case study. However, as emphasized by Ozdemir2, in pair wise comparison matrices the appropriate number of criteria should be seven as the maximum, from the point view of validation, consistency and redundancy. In cases where there are more than seven criteria to be handled, it is suggested that the criteria should be clustered and then the maximum number of clusters and subcriteria of every cluster should be limited to seven4.

Jan 1, 2007

In parallel work, the cyanide/silver impregnated activated carbon system was studied for the purpose of developing an alternate cyanide removal system. It was found that free cyanide can be reduced from 20 ppm to below 10 ppb with a fixed bed of silver impregnated activated carbon, since such cyanide removal might be applicable to gold mill effluents, the investigation was extended to the cyanide/gold impregnated activated carbon (GIAC) system. Batch tests were conducted varying the gold content of activated carbon, carbon/CN ratio, stirring speed, pH of the initial solution, and the reaction temperature. The adsorption isotherm of cyanide/gold impregnated activated carbon system was also studied. The results of these batch tests show that the behaviour of the cyanide/GIAC system is very similar to the cyanide/silver impregnated activated carbon system variation of the gold content of the impregnated activated carbon has some influence on the cyanide adsorption rate. The latter is mainly increased, however, by increasing the GIAC/CN ratio. The activation energy was determined to be 3.12 kca1/mole (13.08 kj/mole) and the Au(CN)2 saturation at 194 µ M/g NORIT ROX O.B. The experimental results of reaction temperature and stirring speed show that the adsorption of free cyanide on such activated carbon is controlled by pore diffusion inside the activated carbon particle or by surface reaction. The adsorption isotherm follows the linear model and it is favourable for the cyanide/gold impregnated activated carbon system.

Jan 1, 1994

By D. Diggins

Experimental apparatus for the determination of powder wettability is described. The principle of the technique is based on the measurement of the equilibrium capillary pressure in a packed bed of particles. Both the macroscopic solid-solution-vapour contact angle, e, and the specific surface area, A(m2g-1), of the powder, can be obtained. Experiments on angular quartz particles have been performed. A wide range of situations have been covered: hydrophobic and hydrophobic particles wetted with water, a variety of organic liquids and solutions of surfactants. The results show that reliable and reproducible values for 0 and A for angular and relatively coarse powders can be obtained with the proposed equipment for advancing liquid fronts in the absence of soluble surfactants. In the latter case and for receding liquid fronts in general, only qualitative trends have been obtained.

Jan 1, 1992

By Dix, E. H.

THE percentage of manganese used in commercial aluminum alloys is small, and yet this element is an important addition to some very valuable alloys. When used alone with commercial aluminum containing iron and silicon as impurities, the usual percentage in wrought materials is from 1 to 1.5 per cent., whereas castings may contain as much as 2 per cent. An aluminum-manganese alloy containing nominally 1.25 per cent. manganese is much used in sheet form for the manufacture of cooking utensils and other articles requiring a little greater strength and hardness than could be obtained with commercially pure aluminum. It is also used for various purposes in the form of rods, tubes and pipes. The aluminum-manganese alloys, both wrought &apos;and cast, offer excellent resistance to many kinds of corrosion attack. The U. S. Naval Gun Factory uses an aluminum alloy containing from 1 to 2 per cent. each of copper and manganese, for both castings and forgings. Manganese is also used, up to about 1 per cent., as a minor alloying .element in several of the strong aluminum alloys of the duralumin type. It is felt that the role of this element when thus used has not been fully understood, but it is believed that the results obtained in this investigation will throw additional light on the subject. The earlier work on the system aluminum-manganese was general in nature, and no detailed investigations of the relations existent in the useful aluminum-rich alloys have been reported. Guilletl1in 1902 surveyed the system, and Hendrichs2 in 1908 published an equilibrium diagram which, although based on .few data, is often used in the literature. Fragmentary work has also been done by other investigators."

Jan 1, 1927

By Akira Yazawa

The continuous converting has attractive advantages, but further experimental studies on the slag are required, when the process is considered thermodynamically. The summarized experimental results, obtained with iron silicate slag and with ferrite slag and results relating to actual operation are described and discussed in this paper. At first, equilibrium relations at controlled oxygen potentials among three melts of silica-saturated iron silicate slag, white metal and copper are investigated. The results obtained for slag agreed with the thermo-dynamical predictions. Namely, to suppress a magnetite separation, the system should be at high temperature; in the case of the S02 gas of 10 kPa, for example, magnetite did not separate from the slag at 1300°C, but at 1250 and 1200°C the slag was saturated with magnetite even at lower SO2 pressure. Copper losses caused by dissolution of its oxide increased with increasing 5O2 pressure, and were slightly lower than those reported in previous papers without the matte phase. When the continuous converting slag does not contain any appreciable amount of silica - in contrast to the conventional smelting slag ferrite slag would form, but there was no published fundamental work on-ferrite slags. Hence, the melting behavior and activities of the system CaO-Cu2O-Fe2O3 have been investigated. The liquidus diagram in nitrogen atmosphere was, constructed using both thermal analysis and quenching method. The low liquidus temperature region without magnetite separation was found in the part of low content of Cu2O in the section Cu2O-CaO-Fe2O3 and Cu2O?Fe2O3¬CaO?Fe2O3. The activity of Cu2O in the system was also measured. Slags, composed-of CaO, Cu2O and Fe2O3, in platinum crucibles were equilibrated at 1250°C and controlled oxygen pressures. After quenching, the-composition of slag and platinum crucible were determined qualitatively. On the thermo-dynamic analysis of the results, iso-activity lines were drawn, and it was shown that the slag in the converting furnace of the Mitsubishi process exists in an adequate region of the composition triangle.

Jan 1, 1976

"INTRODUCTIONMany of the facilities and much of the equipment available to the Generic Mineral Technology Center for Respirable Dust are highly specialized and therefore, unique to the universities associated with the Center as illustrated in FIGURES 30 through 39.For example, a sample bank of 1300 U.S. coal specimens housed in the Coal Research Section, Deike Building of The Pennsylvania State University has been characterized for physical, elemental, mineralogical and maceral compositions. The results of this research have been used to initiate a study of the relationship between pneumoconioses and coal properties. Selected samples from this bank have been used in animal (primate) studies at the Milton S. Hershey (Penn State) and West Virginia University Medical Centers. These laboratory facilities for research in the medical and biological disciplines is state-of-the-art and includes a primate colony where dust research is currently underway. The Materials Research Laboratory and the Rock Mechanics Laboratory at PSU, and the Mechanical Systems Design and Control Laboratory, the Rock Mechanics Laboratory and the Mine Electronic System Laboratory at WVU are equipped for fundamental research on dust generation and characterization. While the majority of respirable dust research projects fall into these two categories, dust generation and characterization and interaction of dust and lung, there are other laboratory facilities available to the Center which are unparalleled in the type of equipment and expert personnel that they contribute to the program. The Mine Particle Laboratory located at the University of Minnesota and the Diesel Engine Laboratory at Michigan Technological University are examples. They house equipment and instrumentation that is unique to these facilities. much of it having been developed specifically for dust research by the research scientists there. The dust collection equipment and the fine particles measurement, characterization and analysis apparatus are essential to research in the areas of dust collection, particle characterization and diesel particulates. In addition to university laboratories, the research facilities of the National Institute for Occupational Safety and Health (NIOSH) are available to the Center through its relationship With West Virginia University."

Aug 31, 1989

By John T. Crawford

Introduction Loading and hauling systems are evaluated in open pit mining for new properties, expanding existing operations, changing systems or equipment, and equipment replacement analysis. The objective of such evaluations is to determine the equipment needed to handle planned tonnages at the lowest cash flow cost. Cash flow costs are used to combine capital outlays with operating and maintenance costs. Leasing costs could be substituted for capital costs with appropriate modifications to calculation procedures. These modifications will not be covered. This chapter will describe methods of evaluating loading and hauling systems, concentrating on some of the more often raised questions concerning quantitative data. While the methods described are not the only ones in current use, they have a record of proven reliability. The shovel and haulage truck system is used In the examples because of its common use in open pit mines. In medium to large open pit mines, electric shovels and diesel-electric drive haulage trucks are normally used. The basic ideas presented in this chapter apply to all loading and hauling systems, with appropriate modifications. The process of performing a shovel and haulage truck evaluation can be time-consuming and tedious because of the quantity of data involved, but it is not particularly difficult. The examples used to Illustrate shovel and haulage truck evaluation are based on a hypothetical open pit mine operating 350 days per year producing 31 750- 000 t (35,000,000 st, 100,000 stpd) annually, of which 11 110 000 t ( 12,250,000 st, 35,000 stpd) are ore. Selection of the optimum shovel and haulage truck fleets will be shown. The principal sources of data for the examples or any other equipment evaluation are equipment manufacturers and actual operations. Whenever possible, actual operating experience should be used to verify estimates. The quantitative data presented herein are unrelated to a specific existing mining operation.

Jan 1, 1979

By D. H. Magoon

The zinc smelter of Cominco Ltd. at Trail, B.C. Is the largest In the western world. A total of 550.000 tonnes of concentrate are proceed at the smelter annually. Approximately 80% of the zinc concentrate is roasted and the remainder Is treated by aqueous oxidation preaaure leaching. The zinc concentrate roasting and sulphur dioxide gas processing plants have undergone many changes over the years. This paper describes the processes and equipment currently used for concentrate roasting, S02 gas cooling and cleaning, mercury removal, sulphuric acid production liquid S02 production, and tall gas S02 scrubbing. The recent Installation of an advanced process control system for the operation of these Integrated processes Is also described.

Jan 1, 1990

By A. Paviani

The subject of this session is "Equipment Installa­tion, Recent Developments". This is a subject which is not usually addressed at conferences of Foundation Engineering. It is rare to find sessions dealing with the technological side of deep foundations, a subject which only recently seems to have aroused sufficient interest at national and international conferences. It is therefore natural for the subject of "Equipment", or the tools used to implement the various "technologies", to be over­looked or mentioned only occasionally during the discussion of other issues. At conferences, most of the attention is attached to research and to the theoretical interpretation of the performance and behaviour of deep foundations, as well as to establishing the most suitable calculation algorithms and approaches for the study, design and control of foundation structures. It is almost as if the subject of equipment is felt to be less important or, perhaps, that it is considered to belong more strictly to mechanical engineering than to civil engineering.

Jan 1, 1994

By I KylmSkorpi, H Mansikkaviita

The traditional direct-heated drying process has been replaced by the steam drying process in non-ferrous metal smelters, where steam is available from waste heat boilers. Many recent projects have selected Kumera Steam Dryers in equipping a new production line or modifying an old production line. The industrial performance of the steam dryers has shown significant energy saving and emission reduction. The steam dryers have been operated at high availability and long maintenance interval. As the process principle of Kumera Steam Dryer is different from other equipment, the set-up for steam dryer plants is configured to fit the smelter site and operation conditions to achieve optimal performance. This article discusses the equipment involved in the steam drying process and their combination options.

Jan 1, 2008

By Yuan Lu, Yiming Rong, Richard D. Sisson Jr

With the development of quench technology, there is a trend of using gas quench to replace liquid quench for less distortion and residual stress. The fundamental difference between the liquid and gas quench is the heat transfer coefficient, not only the values but also the shape of the curve as a function of temperature. The equivalent heat transfer coefficient for the liquid and gas quench is analyzed by simulations and experiments. Even it may result in the same hardness in the liquid and gas quench, the steel microstructure may be different because of the different cooling processes, and therefore other steel properties, such as toughness, may be different. The cooling process, microstructures and properties such as hardness and toughness should be examined when designing the liquid or gas quench processes.

Jan 1, 2015

By L. A. Ayres da Silva, J. P. G. Negri, A. L. M. Ayres da Silva

"Rock hardness is dependent on the type and quantity of the various mineral constituents of the rock and the bond strength that exists between the mineral grains. As the book “The Complete ISRM Suggested Methods For Rock Characterization, Testing and Monitoring:1974-2006” explains, hardness is a concept of material property. As such, the quantitative measure of hardness depends on the type of the test employed.Among the three types of tests that have been used to measure the hardness of rocks and minerals: 1) indentation tests; 2) dynamic and rebound tests; 3) scratch tests, the authors of this paper chose indentation tests, more specifically the Vickers test, and complementary verified the correlation between the results of the Schmidt sclerometer tests (rebound tests) and the Vickers microhardness tests in a set of the same 9 (nine) granite rocks.The objective of this research was to verif y the correlation of one created index, based on the Vickers test that can be able to represent the rock material hardness. We know that Vickers tests determine the microhardness of individual rock minerals. A pyramidal shaped diamond is applied to the surface with a specified force. The area of the permanent residual deformation divided by the applied force is a measure of the hardness. Using the relative participation of the mineral components of the rock, we established a hardness index denominated EVM (Equivalent Vickers Microhardness).The correlation of the EVM with others strength properties and application parameters like UCS (Uniaxial Compressive Strength) to study sawability of granite blocks have presented very good results. The association of equivalent microhardness with others strength parameters, allowed to find powerful algorithms for analyzes of the rock materials behavior under diversified circumstances, as the sawability of granite blocks, as we can see in Fig. 1.Other very interesting correlations were found as the EVM values and that were obtained by the use of the Schmidt impact hammer for the superficial hardness determination."

Jan 1, 2015