Search Documents

By P. Oghazi

It is possible to have traceability in the mining industry, by parameters and signatures like particle mineralogy, mineral association, texture and mineral liberation. The study is on an apatite-iron ore deposit at Malmberget, Sweden, and characterizes an ore body both mineralogically and texturally in a quantitative manner by using analytical methods like optical microscopy, microprobe (EMPA) and an automatic SEM based system, Particle Texture Analysis (PTA). The mineralogy was evaluated by PTA and characterized by modal mineralogy, mineral liberation and mineral associations. Magnetite has a simple outline and straight grain boundaries and the gangue minerals have a finer particle size with a more complicated texture. The PTA analysis also shows that apatite is associated to magnetite as mixed particles, while smaller grains of magnetite are inclusions in feldspar. Result from particle texture analysis shows that there is a connection which link to the mine-to-mill context, and it may be used to create traceability. This link is not the associations of the main ore mineral magnetite, nor the modal mineralogy. Instead, it is the mineral associations of contaminating minerals (apatite and feldspar) that appear to be most promising since they survive from mine to mill. The modal mineralogy may be used to understand how contaminated minerals break into or out of particles size fraction during grinding.

Jan 1, 2010

By B. M. Kunar, C. S. N. Murthy, B. Rao K

Rock particle size has a very important significance in the mining industry, starting from blasting till the mineral processing. The present study was carried out to understand the particle size distribution in various sieves after conducting the ball milling process. The time of the grinding process was varied at different intervals. It was observed that 80% of the particles of both granite and marble rock samples passed through the 4800 μm sieve when subjected to grinding time of 40 minutes. Also, it was observed the number of particles that were retained in the smallest sieve of <75 μm was higher in the case of granite sample when compared to a marble sample. INTRODUCTION India is a major exporter of granite and marble stones. The major use of marbles and granites are constructing walls and floors. There are several machining processes that are applied before it is used as floors and walls. During this process, wastes are produced these wastes are used in various ways. These include use of powders for clay products (Segadães, Carvalho, & Acchar, 2005), as an additive in cement production (Aruntaş, Gürü, Dayi, & Tekin, 2010), to enhance the properties of brick ceramics (Saboya, Xavier, & Alexandre, 2007), in constructing bricks (Bilgin et al., 2012) and as an additive in concretes (Aliabdo, Abd Elmoaty, & Auda, 2014). Usually, the powder form of marble and granites are used as an additive in the above-mentioned applications. Powders of marble and granite are obtained through the grinding process. One such process of grinding is the ball milling process. In the ball milling process, a quantity of samples along with the charge quantity consisting of steel ball is subjected to a grinding process within a closed chamber as shown in Fig. 1. An even particle size can be obtained through sieving the material after subjecting it to grinding. The present study is planned to understand the particle size distribution in various sieves due to varying time and charge quantity in the experiment. Only time was varied to understand the amount of particle distribution in the case of granite and marble rock samples and a comparison is drawn. A statistical model was developed for marble rock specimen considering the data obtained by varying time and charge quantity in the ball mill experiment.

Jan 1, 2019

By Bjørn Nilsen

"INTRODUCTION/BACKGROUND Weakness zones or faults containing clay-rich gouge represent one of the most challenging rock mass conditions to be encountered during tunneling. In Norway, such conditions count for a large part of the rock support costs, and in cases where the rock support has been insufficient, serious instability and cave-in have in many cases been the result. Most commonly, such cave-in has occurred after water filling of hydropower tunnels, but in some cases it has also occurred in tunnels under excavation and in completed “dry” tunnels. To avoid instability, two important requirements have to be fulfilled: 1) The location of the weakness zone and its character have to be identified in time. 2) The rock support has to be sufficient to withstand the loading caused by the zone. An incident which really brought the problems related to swelling clay into focus was the cave-in at the Hanekleiv road tunnel in 2006. Here, rock fall from the roof as shown in Figure 1 occurred unexpectedly about 10 years after the tunnel was completed. Fortunately this happened at a time with very little traffic, and nobody was injured. This incident emphasized the significance of the issue of swelling clay, although it was found to be caused also by gravitational collapse of the clay-rich gouge material of the weakness zone, and not related to swelling only (Nilsen et al. 2007).In this paper, main focus will be on discussing the characteristic features of swelling clay, test procedures which are being used for characterizing swelling clay, and the reliability of the results from testing for use in support evaluation and design in conditions with swelling clay. It is generally well known that swelling clay may cause considerable pressure on support elements, but quantifying this pressure for reliable analysis and design of rock support is still a great challenge."

Jan 1, 2016

By Steve Kral

In recent years, junior mining companies, mostly listed in Canada, have taken a beating in the finance markets. Simply put, potential investors have been leery of sinking millions into exploration and mining projects due to volatile commodities prices and an uncertain regulatory climate in developed and developing countries. The 2014 edition of the Prospectors and Developers Association of Canada (PDAC), however, seemed to be a bit different for some juniors. Equity valuations have improved and metals prices appear to be stabilizing. So, for some of the stronger junior companies, there is some hope. Merger and acquisition (M&A) activity is picking up and, believe it or not, companies are raising some capital. Billed as the largest annual mining meeting in North America, the PDAC conference attracted more than 25,000 mining and exploration professionals from around the world. Organizers were anticipating attendance to break the 30,000 mark. But, given the state of the exploration end of the mining business, 25,000 is still a respectable number. Junior companies that are in the project feasibility stage, or have made promising discoveries that stand a good chance of proceeding to production, are being looked at by potential investors. Those are the survivors of the last three years of dismal M&A activity. On the other side are the juniors that are still around ? and there are plenty of juniors that were at the PDAC last year but have since disappeared ? but have little or no working capital. One analyst calculated that there are about 850 companies with less than $200,000 in working capital and about 600 with negative working capital. This will likely result in fewer junior mining and exploration companies as the year progresses but the ones that remain should be stronger.

By J. J. Pavlica

Grinding in steel mills adversely affects the flotation removal of pyrrhotite from magnetite ores. To elucidate the effect of grinding media on the floatability of pyrrhotite, rest potential and short-circuit current measurements were made on electrode combinations of pyrrhotite-mild steel and pyrrhotite-stainless steel. Galvanic contact of pyrrhotite with mild steel increased the rate of surface reactions on pyrrhotite in air-exposed and oxygenated solutions. It was postulated that the formation of &apos; an iron hydroxide coating on the pyrrhotite adversely affected its floatability. Its formation was minimal when pyrrhotite was contacted with stainless steel. Fine magnetite particles caused slime coating on pyrrhotite surfaces by magnetic interaction and impaired the flotation of pyrrhotite.

Jan 1, 1982

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 S. S. Peng

A well designed mining plan is one which minimizes the cost and the mining induced problems and maximizes the recovery of the coal reserve. In order to minimize the negative effects on surface structures caused by ground subsidence process due to underground mining activities, two kinds of practices are commonly employed by the mine operators. One is the support techniques which leaves an area of coal un-mined or partially mined beneath the structure to be supported. The other is the protection techniques which protect the structure when it is subsiding with ground taking advantage of the ground subsidence process (Luo et al., 1992). In designing the supporting techniques, the only currently available method in the U.S. is the one stated in the Pennsylvania Underground Coal Mining Rules (1985). However; The size of the support area designed by this method will be excessively large resulting in wasteful use of coal reserve when the overburden depth is more than 350 ft. A more scientific method is proposed in this paper for de-signing the support area. This method is based on a large amount of subsidence data collected throughout a number of major U.S. coal fields and the authors&apos; experience with monitoring and protecting surface structures undermined by longwall panels. It considers the critical deformation in-dices that a structure can tolerate, and depth and height of underground extraction. The support area designed by this new method will not only assure the safety of the structure to be supported but also maximize the extraction of the coal reserve.

Jan 1, 1993

By William E. Lamont

The Mineral Resources Institute (MRI) of the School of Mines and Energy Development (SOMED), University of Alabama conducted studies to determine the potential for upgrading the Eastern Devonian shales by flotation. Results of those studies indicate that flotation concentrates containing 150 liters of oil/t (36 gal/t) can be produced from shale containing 50 liters of oil/t (12 gal/t) as determined by Fischer Assay with good recovery of the kerogen. Organic carbon and trace elements such as molybdenum, vanadium and uranium also are concentrated with the kerogen. Kerogen concentration was found to be a function of the size of grind.

Jan 1, 1983

By B. W. Cavender

"World-class manufacturing" (WCM) techniques can be applied in milling operations to substantially improve productivity and reduce costs. Through the use of "just-in-time" and "total quality control" practices, WCM methods establish an environment for continual and rapid improvement in all aspects of production operations, with particular gains in product quality, costs, flexibility, employee involvement, and responsiveness to customers. This paper examines WCM techniques that can be utilized specifically in the mill, and their influence on plant configuration, organization, and scheduling practices; equipment selection and maintenance methods; training; the role of supporting staff; and methods of data collection and analysis.

Jan 1, 1993

By R. A. Limons

Natural ores, sinters, and pellets were subjected to a carbon monoxide reduction-disintegration test under laboratory conditions including a simulated blast furnace gas and a 1000°F temperature. The most significant findings were that: 1. Self-fluxed pellets broke down to a greater extent than either the acid pellets or the acid or self -fluxed sinter. 2. When pre-reduced, both the acid and self-fluxed pellets had very good resistance to breakdown.

Jan 1, 1964

By R. Woods, J. D. Wright

INTRODUCTION The Endako deposit was first explored in 1926, but development waited until the early nineteen sixties. It first came under the control of Placer Development in 1963, and early in 1964 a decision to bring it into production was reached. The deposit is located near the geographic center of British Columbia, and is served by an east-west communication system including a paved highway, mainline railway and good telephone, teletype, and computer facilities. The plant area is shown in Figure 1. The operation is known as the Endako Mines Division of Canex Placer Limited of Vancouver. First production was achieved in June, 1965, at a nominal rate of 10,000 tons per day, but it soon was closer to 15,000 tons per day. In 1967, two new grinding and flotation sections brought capacity to the present rate of approximately 27,000 tons per day. With mill heads of around 0.15 percent MoS2, production is about 14,000,000 pounds of molybdenum per year. A flowsheet of the operation is given in Figure 2. A legend for this flowsheet is given in Table 1. Published ore reserves are estimated at 214,500,000 tons at an average grade of 0.143 percent MoS2. PRIMARY CRUSHING The 85 or 100-ton haulage trucks dump over a grizzly into a 42 inch x 65 inch C.A.C. (Canadian Allis Chalmers) gyratory crusher.

Jan 1, 1976

By Z. Rogovin

In order to develop more accurate procedures for scale-up and design of semi-autogenous-grinding mills through detailed mathematical models, a better understanding of the charge motion and rock/ball segregation is needed. To achieve this a 0.61 m (2.0 ft) diameter x 0.305 m (1.0 ft) length plexiglas mill was constructed as a scale model of a commercial SAG mill. Rock motion in the rotating mill was simulated using various sizes of ceramic balls. Quantitative measurements of dynamic angle of repose, water and slurry motion, holdup and size segregation of the charge were taken. In addition, a video-presentaiton (available to the public) was prepared to elucidate charge and water motion at various mill speeds, charge volumes, rock size distribution and flow rates.

Jan 1, 1985

By V. Srivastava, T. Ghosh

The modeling and simulation of semiautogenous (SAG) mills have been widely used in the design and optimization of mill performance in terms of its power draw, processing capacity and product size distribution. However, these models are solved under steady approximation and do not provide any information on mill charge distribution in real time. 7KLVSDSHUDWWHPSWVWRFKDUDFWHUL]HPLOOFRQWHQWVE\VROYLQJ:KLWHQ¶V¿UVW RUGHUFRQWHQW EDVHGPRGHOLQWKH0$7/$% Simulink environment. The parameters in the model, such as breakage rate constant, discharge rate and appearance function, were estimated using process and design data collected from a gold mine operating in Alaska coupled with a nonlinear parameter estimation scheme. This model was then used to predict the dynamic responses of other key operational variables, such as mill power, bearing pressure, charge level and product size distribution. The transient response of mill behavior with respect to changes in feed size distribution, tonnage and mill feed water is also presented. This dynamic simulation approach can be used for practicing different control strategy and training purposes. The observed response of mentioned variables was validated using dynamic response data from the plant to encompass operational characteristics of SAG mill behavior.

By R. T. Swinderman

This paper discusses a series of tests designed to help answer the age old question: ?How much does the belt cleaner wear my belt?? The experimental set up and test method are described. The main variables are: belt cleaner blade materials, cleaning pressures, cleaning angles, belt speeds, and belt top cover grade. The bulk material used is a standard test-grade silica sand. The measured results include: blade mass loss, belt mass loss, and cleaning efficiency.

Jan 1, 2010

By Bob Newbery, Kenneth W. P. Eng. Kolthammer

SUMMARY Reference is made to the reasons for drying and the equipment is described that is available from which the engineer can make a selection. The factors affecting this decision are described. In the case of drying, design and sizing are ultimately developed empirically and no theoretical approach has been advanced.

Jan 1, 1986

By R. K. Davey

Before the introduction of computerized procedures, mineralization modeling (compilation of level maps), ultimate pit studies, ore reserve compilations, and long-range mine planning all were performed manually. In fact, much of the basis for today&apos;s computer programs was derived from manual procedures and actual experience of mining engineers and geologists.

Jan 1, 1979

The value of US industrial mineral output last year was $20 billion, a 12% decline from 1981. A glance at the accompanying table and a review of the comments made by several contributors reveals how poorly many industrial minerals fared during 1982. Bromine and peat posted a 6% increase in production while recovered sulfur showed only a 3% gain over 1981. Pumice, salt, and dimension stone managed to stay more or less even with 1981 production. However, most industrial minerals posted losses for the year from 3% for vermiculite, sodium carbonate, and gypsum to 49% for ilmenite. Naturally, the depressed economy is to blame for decreased production and consumption. Low steel and auto production, lower housing starts, and many other factors impacted the industrial mineral industries. Hopefully the worst is over. Interest rates are down, energy costs are decreasing, the automobile and housing industries show signs of picking up. Perhaps the 1983 annual review will be less gloomy. Many thanks to these industrial minerals technical committee members for their contribution to this year&apos;s annual review: G. S. Austin, E. S. Montgomery, H. P. Ehrlinger III, D. B. Jorgensen, R. L. Parratt, J. F. Burst, W. Mallory, N. C. Trivedi, and N. K. Olson.

Jan 5, 1983

The vast coal resources of North Slope, Alaska can be expected to attract substantial interest because the nearly flat lying coal beds of the coastal plan are specially amenable to surface mining. Mining on a scale large enough to justify coal development in this area could have severe environmental effects. The mitigation would be uncertain because large scale coal mining and reclamation operations have not been carried out in the arctic The deficiency of the scientific data base is another factor that requires consideration if coal mining has to develop in accordance with the objectives of PL 95-87. The objective of this paper is to establish the interrelationship between the problems due to permafrost and factors in reclamation of post mining land in order to find ways to transform nature in a rational and purposeful manner and to suggest specific reclamation approaches that may be appropriate in this region.

Jan 1, 1986

By V. Shchukin

According to the scientific views formed by the middle of nineteen seventies there should be no possibility of commercial diamondiferous kimberlites in the north of the west European platform. However a later analysis of the geological data gave rise to the concept that diamond bearing kimberlites would be present in the north but on the mineralogical level they would differ from kimberlites of South Africa and Yakutia. Further investigations resulted in the confirmation of these conclusions and with discovery at the beginning of 1980 of diamond bearing kimberlite pipes in the Arkhangelsk region.

Jan 1, 1995

By Downing Terry L.

Dry mineral beneficiation methods have been developed for separation of borate minerals from montmorillonite claystone gangue. The methods include the use of newly developed dry high intensity magnetic separators. The application of these methods has the potential for economic benefit at U.S. Borax Inc. in three areas: ? Processing surface impoundments (ponds) material. ? Pre concentrating ore to be fed to primary refinery. ? Concentrating borate minerals to produce potential products.

Jan 1, 1995