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By Charles P. Lazzara, Alex C. Smith, Mark W. Ryan

The U.S. Bureau of Mines conducted a study to evaluate the effect of ventilation on the performance of automatic sprinkler systems in extinguishing wood crib fires. Experiments were conducted at airflows of 0, 0.76, 1.5, 2.5, and 4.1 m/s. Two experiments were conducted at each airflow, using 74° C fast response pendent sprinklers in one experiment and 74° C fast response horizontal sidewall sprinklers in the other experiment. In the experiments at airflows of 0 and 0.76 m/s, sprinklers were located directly above the fire and 2.4 m upstream and downstream of the fire. The sprinkler directly above the fire was the only sprinkler to operate with no discernible difference in the suppression capability of the pendent and horizontal sidewall sprinklers. In the experiments at airflows of 1.5 and 2.5 m/s, sprinklers were located directly above the fire and 2.4 and 4.8 m downstream of the fire. The sprinkler located 2.4 m downstream was the only sprinkler to operate with the horizontal sidewall sprinkler being more effective in extinguishing the wood crib fire. The average response times of the sprinklers at airflows of 0.76, 1.5, and 2.5 m/s were 3-1/2 times the average response time of the sprinklers at 0 m/s. The results of this study will help enhance the safety of the nation's miners.

Jan 1, 1993

By A. Lyndon

Vertical and lateral load tests were carried out on two 13 m deep bored cast-in-place instrumented piles, socketed into weathered sandstone. The first pile, 1200 mm in diameter, was loaded vertically to a maximum of 16000 kN and then loaded to failure under lateral load (1900 kN). The second pile, 1500 mm in diameter, was tested under lateral load up to a maximum of 2400 kN. It was found that the deflections of the 1200 mm pile were more than twice those of the 1500 mm pile under similar loads. The soils on the site are not easily tested in the laboratory, or by conventional insitu site investigation techniques, parameters needed in design can only be reliably obtained from pile test results. In this report shear moduli are back analysed from the vertical load test and the two lateral load tests. For these similarly installed piles very different design parameters were determined from the lateral load tests, the only known major difference between the piles being that the 1200 mm pile was loaded vertically before it was loaded laterally. Changes in G values needed to match performance under vertical load if applicable to lateral loading could have accounted for a significant amount of the difference.

Jan 1, 1989

By G. Onal, E. Gock, H. Dincer

"During the conventional chromite dissolution process; chromite ore concentrates were ground to at least <90 µm using the ball mill and after adding Na2CO3 and leaning material (instead of CaCO3 also residues from the leaching process) at a ratio of e.g. 1:0.75:1.2, depending on the specific formulation, follows the digestion e.g. in a rotary kiln, heated in countercurrent. The reaction time is 3 to 8 h. The calcine is comminuted and leached with water or a thin chromate solution. Depending on the type of ore used, the yield is 75-85 %. The disadvantage of the above-described process is that it is impossible, using current technology, to achieve a complete digestion of the chromite ores and that the chromium-containing residues have to be disposed of as special waste, involving a large financial effort.The subject of this study was the investigation of the effect of vibratory milling on chromite dissolution. The impact stress in the vibratory mill causes the mechanical activation of chromite, which is characterised by lattice defects. The degree of mechanical activation can be quantified by measuring the relative X-ray diffraction intensities at the parent lattice planes of chromite. Each relative X-ray diffraction ratio correlates with a certain degree of digestion. As opposed to vibratory milling, a complete digestion of chromite using a ball mill is impossible, even at extremely long grinding times.In this investigation a chromite concentrate from Pulpinar/Kayseri with content of 44 % Cr2O3 and the Eccentric Vibratory Mill was used. In order to verify the effect of the vibrating grinding on chromite dissolution, reaction kinetic investigations on digestion and leaching were carried out."

Jan 1, 2003

By F. Burat

At the present time, methods of mining and coal preparation produce tones of coal fines. The removal of water from these fines is necessary for economical and technological reasons. Supplementary processes that utilize different physical and chemical methods have been developed to in-crease the productivity of mechanical dewatering processes. Researches have shown that chemical reagents used along with conventional systems diminish moisture and increase the capacity and the yields of the dewatering method. In this study, the parameters of the vibrating screen (incline, frequency, feeding rate and screen size), the effects of the application of additional vertical mechanical vibration and surface active reagents (CTAB, SDS, Umectante B-70 and Kerosene) were investigated. At the end of the optimization experiments, 61.0% moisture was decreased to 42.3%. By keeping optimum conditions con-stant, the experiments have been conducted to determine most effective reagent. 41.2% moisture has been obtained with 5 g/t CTAB at the normal pH of the pulp, which were 7.25. By using vibrating screen with combination of the vertical vibrating mechanism, CTAB gave the best result of 40.7% moisture. Finally, the effect of increased surface area of the screen has been investigated and de-creased the moisture level to 38.7%.

Jan 1, 2014

By Linge H. G

The effect of sodium pyrophosphate and several polyacrylate deflocculants (Freevis 502, 528, 529 and 532; and Maxfloc 1015) on the gold loading on Calgon GRC22 and Norit R035l5 carbons was tested and found to be insignificant in a pulp free enviroument. These deflocculants can therefore be used in plants processing viscous gold pulps without fear of fouling the carbon.

Jan 1, 1990

By B. J. Arnold

Prior laboratory work has demonstrated -that much of the fine ash-forming minerals entering a flotation froth are there as a result of water carry-over from the bulk contents of the flotation cell (Arnold and Aplan, 1986a). Using a bank of four 300 cu ft WEMCO flotation cells cleaning a well-liberated Lower Kittanning seam coal, test results show that the sulfur and ash content of the froth is directly related to the water content of the froth (or inversely related to the percent of solids in the froth). Reagent changes which result in a watery froth produce a higher ash content in the froth. A direct comparison of laboratory and plant results show that the standard laboratory flotation test produces a product higher in sulfur and ash than that produced in the plant. Caution should be exercised when extrapolating laboratory test results to the plant situation. A method of estimating coal flotation product quality in the plant based on laboratory tests is given.

Jan 1, 1990

By Richard R. Klimpel

"This paper discusses the effect of water chemistry, reagent type, and other environmental factors on the performance of sulfide mineral size reduction and froth flotation processes. Two specific problems will be discussed: l.) the importance of appropriately utilizing the electrochemical window that is created in the grinding process to enhance sulfide mineral recovery by froth flotation; and 2) the impact of steel grinding media versus autogenous grinding on the efficiency of sulfide mineral flotation with varying thiol collectors and water sources.IntroductionThe mutual dependency between size reduction and mineral froth flotation is well recognized from the viewpoint of particle size and mineral liberation characteristics. The purpose of this paper is to discuss two less obvious industrial interactions between size reduction and froth flotation that have come up in the various plant optimization studies conducted by this author. These interactions are complex but appear to be important at the industrial level as plant throughput is directly affected, either positively or negatively by such interactions. Examples v.ill be given on how the method of grinding influences flotation and how different water sources influence the flotation behavior of electrochemically sensitive minerals. With each of these interactions, a number of fundamental research studies have shown previously that some effects can be measured under idealized and very small scale experiments. Such research studies will not be cataloged or exhaustingly reviewed in this paper. Whether these same types of effects can be measured in an industrial environment and are economically important is much less certain. This paper will present some rather unique experiences gained from larger scale test experiences which clearly indicate findings that plant operators should be aware of."

Jan 1, 1996

By R. R. Klimpel

This paper discusses the effect of water chemistry, reagent type, and other environmental factors on the performance of sulfide mineral size reduction and froth flotation processes. Two specific problems will be discussed: 1) the importance of appropriately utilizing the electrochemical window that is created in the grinding process to enhance sulfide mineral recovery by froth flotation; and 2) the impact of steel grinding media versus autogenous grinding on the efficiency of sulfide mineral flotation with varying thiol collectors and water sources.

Jan 1, 1996

By J. Engesser

This paper discusses the effect that water chemistry, and water treatment have on pre-fired pellet quality and bentonite-binding effectiveness. A discussion concerning the effect that water temperature, water chemistry, water treatment, and surface area have on disc filter productivity and filter cake moisture is also included. This report is a summary of the data that were presented in five previous research reports, which are listed as references in this paper.

Jan 1, 2003

By T. W. Wlodek

"AbstractThe results of research into the fatigue properties of SAE 1080 carbon steel and nickel-chromium-molylbdenum steel for mining drill rods are analysed and described in detail.The effect of water corrosion on the fatigue strength of drill rods of these two steels in the as-rolled condition has ,been investigated and the beneficial influence of shot-peening on their dry and water-corrosion fatigue strengths determined by employing the method developed previously (1).Eight S-N curves for as-rolled and shot-peened mining drill rods under both dry and water corrosion conditions have been derived and their shape and relative position are discussed. The main features relating to field performance of the drill rods are analysed.Purpose of Research and Outline of ProgrammeDRILLING holes in rock and ore by means of drill rods attached to a pneumatic drill is a basic procedure required in mining operations. Detonation of explosives placed in these holes is at present the only practical method of breaking down the rock and ore.A drilling rod is supported by its bit end in the drilled rock. Its shank end, fixed in the drilling machine, transmits impact energy to the cutting edges of the bit. On the field performance of the drill rod depend a number of basic mining operations such as sinking, drifting, and stoping. The drill rod is there-fore regarded as one of the most important tools used in the mining industry."

Jan 1, 1952

By Ove Alm

Wet and dry specimens of three rocks of approximately granitic composition were deformed at different experimental conditions. These experiments were carried out in order to study the extent to which water, either added or released from mineral reactions, may affect the mechanical properties and the microstructure of these rocks. The experiments were conducted in a Griggs&apos; hot creep apparatus at temperatures and pressures up to 900ºC and 1000 MPa respectively; and most of them were performed in the constant strain rate mode [(1.10-6 < t < 1 • 10-4 s-1 )]. All three rocks were low porosity rocks, and the wet specimens never contained more than 0.9 wt % of added water. The experimental results are, however, quite unequivocal: They show that wet rocks are weaker than dry ones. A significant difference is even found for rocks tested in uniaxial compression at room temperature. A few experiments carried out on specimens obtained from larger prestressed rock cores indicated that the central parts of these cores were more likely to contain more microcracks than the ends. Optical microscope examinations revealed that extensive microcracking takes place even at the highest temperatures, where other mechanisms such as slip and dislocation creep also become important. Very little partial melting could be observed except for the specimens deformed at 900ºC.

Jan 1, 1982

By K. C. Corin, M. S. Manono, R. M. Manenzhe, J. G. Wiese

"Environmental concerns necessitate the recycling of process water within mining operations. Given that recycled water is chemically different from fresh water, and collectors are added such that they adsorb at the liquid-particle interface, changes in the aqueous phase are expected to affect collector adsorption. A Finnish nickel-copper ore was floated in synthetic plant waters of varying ionic strengths and plant waters obtained at Boliden Kevitsa Mine, with aerophine and sodium isopropyl xanthate as collectors. Of the tested waters, the copper thickener overflow was the least conducive to xanthate adsorption and valuable mineral recovery. The nickel thickener overflow, standard process water, and raw water were the most conducive to xanthate adsorption. For the raw water and nickel thickener overflow, increased adsorption correlated with increased valuable mineral recovery. Further, recycling xanthate retained in water affected the selectivity of the collector and hence the concentrate grades.INTRODUCTIONFlotation is a separation process that exploits the differences in the surface properties of the particles being separated. The efficiency of separation is dependent on the degree of hydrophobicity achieved by the particles meant to be floated, which are, in most cases, valuable minerals. The hydrophobicity is in turn dependent on the adsorption of the chosen collector onto the surfaces of the floated particles (Fuerstenau, 1984; Taggart and Hassialis, 1946). Empirical findings suggest that species dissolved in solution strongly influence collector adsorption and overall flotation response (Fuerstenau and Chander, 1986). Due to environmental concerns, it is becoming more pertinent for mining plants to recycle process water and hence limit the usage of potable water. There is an interest to ensure minimal discharge of plant water into the environment, as this water is typically polluted with process reagents that may render it toxic (Levay et al., 2001)."

Jan 1, 2018

By K. C. Corin, M. S. Manono, R. M. Manenzhe, J. G. Wiese

"Environmental concerns necessitate the recycling of process water within mining operations. Given that recycled water is chemically different from fresh water, and collectors are added such that they adsorb at the liquid-particle interface, changes in the aqueous phase are expected to affect collector adsorption. A Finnish nickel-copper ore was floated in synthetic plant waters of varying ionic strengths and plant waters obtained at Boliden Kevitsa Mine, with aerophine and sodium isopropyl xanthate as collectors. Of the tested waters, the copper thickener overflow was the least conducive to xanthate adsorption and valuable mineral recovery. The nickel thickener overflow, standard process water, and raw water were the most conducive to xanthate adsorption. For the raw water and nickel thickener overflow, increased adsorption correlated with increased valuable mineral recovery. Further, recycling xanthate retained in water affected the selectivity of the collector and hence the concentrate grades.INTRODUCTIONFlotation is a separation process that exploits the differences in the surface properties of the particles being separated. The efficiency of separation is dependent on the degree of hydrophobicity achieved by the particles meant to be floated, which are, in most cases, valuable minerals. The hydrophobicity is in turn dependent on the adsorption of the chosen collector onto the surfaces of the floated particles (Fuerstenau, 1984; Taggart and Hassialis, 1946). Empirical findings suggest that species dissolved in solution strongly influence collector adsorption and overall flotation response (Fuerstenau and Chander, 1986). Due to environmental concerns, it is becoming more pertinent for mining plants to recycle process water and hence limit the usage of potable water. There is an interest to ensure minimal discharge of plant water into the environment, as this water is typically polluted with process reagents that may render it toxic (Levay et al., 2001).Recycled water, however, has been shown to adversely affect flotation. Reagent efficiency can be reduced due to increased suspended solids. A loss of mineral recovery can occur due to competitive adsorption between reagents and other dissolved species, loss of reagents due to precipitation, and unwanted reactions. Further, a reduction in grade can occur due to non-selective coating of reagents on valuable and gangue minerals, and hydrophobic coating of microbiological material on gangue, causing unwanted flotation. Yet despite these drawbacks, water reuse has the advantages of minimal fresh water use and reduced reagent consumption by recovering the unconsumed reagents retained in wastewaters (Bruckard et al., 2011; Levay et al., 2001; Shengo et al., 2016; Slatter et al., 2009)."

Jan 1, 2018

By Michael Beattie

A large open-cast limestone mine had its blasting operations severely restricted by the imposition of limiting PPV levels to protect a water pipe-line passing through the mine property. Attempts were made to measure the strains induced in the pipe by ground vibrations, so that a less restrictive blasting limitation could be established on a scientific basis.

Jan 1, 1992

By Y Peng, B Guo

In gold processing plants, the water from the cyanidation stages is treated to detoxify cyanide species and this recycle water becomes the main part of the process water. Despite the low concentration of free and weak acid dissociable (WAD) cyanides in process water, the recoveries of gold and silver is still affected during flotation, especially when gold and silver are associated with iron sulfide minerals. This is a case at the Hidden Valley (HV) Mine. In this study, the effect of free and WAD cyanides on gold and silver recoveries by flotation from the HV Mine was considered.WAD cyanide (WAD CN) was prepared by mixing sodium cyanide and copper sulfate at a cyanide to copper ratio of 3:1 dosed at different cyanide concentrations. It was found that both free and WAD CN depressed gold and silver and particularly iron sulfides in flotation. The depressed gold and silver recoveries were closely associated with the depressed recovery of iron sulfide minerals, suggesting that free and WAD CN may not depress the flotation of liberated gold and silver minerals significantly. It was also found that 10 ppm free cyanide completely depressed the flotation of iron sulfide minerals and WAD CN depression is probably through the WAD dissociation to free cyanide species (mainly aqueous HCN) during the grinding process, resulting from a decrease in pH. Thermodynamic calculation showed that 5.5 ppm free cyanide was released in the end of grinding at an initial WAD CN concentration of 50 ppm. This research provides a guideline to counteract the negative effect of WAD CN in the flotation of gold and silver minerals.CITATION:Guo, B, Peng, Y and Espinosa-Gomez, R, 2013. The effect of weak acid dissociable cyanide on gold and silver flotation in Hidden Valley Mine, in Proceedings World Gold 2013 , pp 341-346 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By Gregory C. More O'Ferrall

Generally pillars in the Southern African hard rock tabular underground mining environment are designed using either empirical pillar design formulae or numerical modelling (analytical) methods utilizing the Hoek-Brown failure criterion. However, none of the pillar design methodologies employed takes cognizance of weak layers either within the pillar material or in the immediate foundation of the pillar. Over the past few years, the presence of a weak layer either within the pillar material or within the immediate foundation of the pillar has resulted in the closure of one platinum mine (Everest Mine), closure of one chrome mine (Wonderkop Chrome) and large-scale instability in a couple of chrome and platinum mines in South Africa and Zimbabwe. A study has been initiated to better understand the failure mode and strengths of the pillars where pillar failure associated with weak layers occurred. Owing to the infancy of the study into the failed pillar strength and failure mechanism, the purpose of this paper is to highlight the circumstances that led to the collapse of mining sections and a shaft, and the difficulty associated with designing pillars in the Southern African chrome and platinum mining operations.

Jun 1, 2012

By S. Nunoo

The shape of particles has a significant effect on the shear strength and deformational characteristics of granular materials. Weathering can change the grain shapes. For example, more weathered sands tend to be rounder regardless of particle size. Particle shape analysis was performed on samples collected from the Questa mine rock piles, a debris flow and the pit alteration scar. In order to increase the validity of the particle shape analysis, 4 persons including 2 geologists and 2 mining engineers were involved in describing the particle shapes. The results of this analysis indicate that rock fragments in the collected samples are mainly subangular, subdiscoidal and subprismoidal. The sphericity and angularity of the rock fragments of the older analogs are similar to those of the rock piles. This suggests that short-term weathering (<100 years) has not noticeably changed the particle shapes at the test locations. Rock piles made of more angular particles are more stable compared to rock piles with rounded particles.

Jan 1, 2009

By Milton C. Neul

As recently as the mid-1930&apos;s, steam and rail haulage were still the primary means of moving large quantities of rock. However, 2- to 5-ton standard on-highway trucks were beginning to be used in the mining industry&apos;s efforts to lower haulage costs. It was quickly obvious that rubber-tired equipment was more flexible, faster and more maneuverable. The trend towards haulage trucks had begun. Now while savings were being realized, the severe operating conditions encountered in open pit operations proved too much for the lightly constructed frames, gasoline engines and highly inflated tires. As a result, a few years later, the first 10 to 15-ton, two-axle heavy duty trucks were designed specifically to operate under off-highway conditions.

Jan 3, 1966

By D. Bai, F. Hamad, S. Abraham

For the integrity of welded structures such as pipelines, the toughness of the heat-affected zones (HAZ) is an important property. This property is often specified in terms of Charpy V-notch (CVN) impact toughness and determined by the standard test method. An experimental study has been conducted in an industrial laboratory to measure the impact toughness of the coarse grain heat-affected zones (CGHAZ) of an X80 line pipe material. The field girth welding conditions in terms of heat input were simulated, together with special edge preparation to improve the targeted testing of the CGHAZ. The effect of toughness of the neighboring regions, in particular the weld metal, on measured impact toughness of the CGHAZ was investigated. The fracture paths of the CVN tested samples were examined by both optical and scanning electron microscopy. The deviation of segments of the fracture path into the weld metal was found to have a significant effect on the measured impact toughness of the CGHAZ.

Jan 1, 2005

By Maria Kuttig, Christian Ruback, Gerhard Tober, Petra Maier

"It has been demonstrated that there is a strong relationship between work hardening with various post heat treatment and cyclic deformation behavior of structural steel S275. This study contributes to a project developing a process for the complex forming of steel, which combines rolling and bending. Due to the complex geometry of the final work piece, the deformation degree varies greatly. The forming temperature, as well as post heat treatruent, influences recrystallization processes in dependence of the local deformation degree, resulting in inhomogeneous microstructure of the work piece, which affects the quasi-static and dynamic properties. Cyclic creep and hardening or softening has been monitored during constant amplitude loading at stresses near fatigue strength in normalized condition. Work hardening, stress relief or recrystallization influence the cyclic deformation behavior and produces cyclic creep effects. Cyclic softening or hardening and creep were observed to occur in parallel. To what extent these properties are noted depends on the deformation degree.IntroductionThis work is part of a research project developing a new process for the three dimensional forming of steel. For the final product the fatigue strength influenced by the forming parameters is very important. Due to its complex geometry, the formed final plate has different deformation degrees. This leads to different recrystallization behavior and heat treatruent will have different effects on the microstructure. The peak deformation degree cp of the plate will be around -0.5 what leads to the analysis using rolling from 22 mm to 13 mm of thickness. The quasi-static material properties are very important for calculating the preliminary design. However, work pieces which are cyclic loaded need fatigue tests to describe the in-service material behavior. [l] For the prediction and to guarantee the wanted life-time of the part cyclic deformation tests are important. [2, p.23-32] When it is assumed that the work piece will only loaded in cyclic tension, fatigue testing will be done from zero to a maximum force value. In preliminary tests this value is the tensile fatigue strength from a Smith diagram. During processing, here forming, work hardening takes place resulting in strengthening. Therefore, in further tests maximum load can be increased to monitor cyclic deformation mechanism in more detail. However, to study cyclic creep and hardening and softening data should be evaluate over sufficient life time and should not fracture too soon."

Jan 1, 2013