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By R. R. Klimpel

This paper demonstrates, using the results of an unusually complete industrial test sequence, what the various interactions are between grind size, collector dosage, and frother type. While particle size is universally acknowledged to be important in optimizing industrial copper sulfide rougher flotation circuits, many of the various interactions that do occur at the industrial level with particle size are still being identified and/or quantified. This study also presents, in a consistent manner, the changes in flotation kinetics that occur as a function of particle size, in a typical industrial circuit along with some insights as to how flotation operators can optimize rougher circuit performance.

Jan 1, 1993

By Y. Xi

In this paper we present an availability approach for determining the capacity of a major bucket wheel excavator (BWE) system to be used in Yuabaoshan surface coal mine in China. Based on previous time studies on other BWE systems for delay times due to internal and external causes, and a four-level maintenance and repair schedule, we develop a model taking into account all random failures and present a fast and simple solution to this highly complex problem. A procedure employing the Markov renewal theory for determination of the distribution of random failure times and failure rate of the whole system, as well as some other factors useful for calculation of the overall system capacity are discussed in the paper.

Jan 1, 1993

By K. P. Bingham

Lime is one of the largest volume chemicals produced in the United States. In 1979 approximately 21 million tons were produced. Lime is, in fact, second only to sulfuric acid as the largest volume basic chemical produced. Lime, also known as quick lime (calcium oxide) and hydrate lime (calcium hydroxide), is the principle alkali used in a multitude of industrial processes. In addition to its use as a principle industrial alkali, lime has experienced dramatic growth in four general market areas during the past 30 years. These four areas are: 1. Water Treatment - Lime is used extensively in treating and purifying water for industrial and potable use, Although significant tonnage is shipped to this market of municipal and industrial water treatment plants, the end-users are widely spread geographically and individual shipments are relatively low tonnage. Lime, which is nonhazardous, can safely be shipped by truck or rail to these small end-users. 2. Municipal and Industrial Waste Treatment - Environmental agencies at all government levels,

Jan 1, 1980

By Wendell E. Bearce

At the, Crescent Valley Mine of the Hanna Coal Company, several 10,000 ton unit trains of 41" x 0 strip coal are loaded per week during the lake season. This is accomplished without the use of any accumulation of prepared coal. A large raw coal pile is built up during the winter months adjacent to two truck dump bins. This is added to whenever trucks are coming in from the pits and trains are not being loaded. During the loading of trains, trucks from several pits dump into the truck hoppers and coal is also dozed in from the pile. At a rate up to 3200 tons per hour this coal is screened, the plus 6" hand picked, the plus 4" crushed, and' all weighed and sampled as it goes directly to railroad cars being handled on two tracks by car retarders. With such an arrangement it is possible to exercise some control over coal quality, if it can be assessed rapidly. For instance, if the moisture rises to a level where it seems probable the BTU per pound will be reduced to the point where the contract calls for penalties, the trucks from, the wettest pit may be stopped, more or less coal may be moved in from the stockpile, or other measures taken to assure that the average BTU of the trainload will be satisfactory.

Jan 1, 1967

By Thomas G. Johnston, Garston H. Blackwell

The development of a block model for a copper molybdenum ore deposit is described. The early use of the inverse distance power estimator, and later transition to geostatistics and kr iging, produced block models suitable for global reserve estimates. Because the global reserve was inadequate for routine mine planning, the production blast hole assays were incorporated into the block model, resulting in excellent local grade prediction. The on site use of small mini, and more powerful personal computers for estimating grades is described. The development of a computer aided, interactive graphic, mine planning system utilizing the grade block model is detailed.

Jan 1, 1987

By Al. Valero, A. Domínguez

This paper appraises the energy requirements for mineral production through an exergy approach taking into account the long-term decline in ore grades. In this context, the exergy required for restoring resources from the dispersed state of the so called Crepuscular Earth into the physical and chemical conditions in which it was delivered by the ecosystems in light of the available technology, is known as exergy cost. The exergy cost is the point of reference in order to evaluate in a single variable, characteristics such as composition, concentration (ore grade) and the state of technology. The ratio between the exergy cost and the minimum thermodynamic cost required to accomplish the same process is called unit exergy cost and provides a measure of the irreversibility of the analyzed processes. Otherwise, the ore grade is one of the main issues which affects directly the costs associated with mining the ore. Hence, the unit exergy costs to produce minerals from progressively lower ores grades by the current technology is analyzed. The unit exergy cost curves are presented for some important minerals such as aluminium, chromium, cobalt, copper, gold, lead, manganese, nickel and zinc, in order to know the trend when the ore grade decreases.

Jan 1, 2011

By A. W. Khair

This paper presents an analysis of the dynamics of bit wear on the productivity of the continuous miners. Two field surveys have been carried out. The first survey was to assess the impact of bit wear on productivity and production cost. The second survey was to study the wear characteristics of the cutting tool (i.e. magnitude, forms, and mechanisms of bit wear). Primary factors affecting bit wear is identified and laboratory experiments were carried out to study the effects of some of these primary factors on wear in detail. Results indicate that bit wear has a significant effect on the productivity of the continuous miners. Furthermore under the severe geologic conditions (i.e. cutting rock partings and roof and floor rocks) bit wear not only hampers the productivity, but also increases the production cost due to a higher number of bit consumption. This study also indicated that bit wear accelerates beyond 20% of the conical height loss which corresponds to 7% of the weight loss. This increase rate of wear is an indicative of higher abrasion between bit body and cutting material, resulting in a dustier environment.

Jan 1, 1993

By Xintan Chang

A computer software package, named CFIRE, for the general ventilation network analysis and fire control, mine fire and/or coal spontaneous combustion, has been developed at Xian Mining Institute in China. It is a multipurpose package with adequate capacities of ventilation map drawing, ventilation network analysis, gob fire simulation, steady state ventilation simulation and transient state ventilation simulation. It was written in a user-friendly style, driven by menus, facilitated by on-screen messages and supported by the allowance of user interferences. CFIRE has used up-to-date research findings focussing on the practical needs of coal mines. This paper discusses briefly also the relevant theoretical principles on which this package has been perceived.

Jan 1, 1989

By S. Sener

In this investigation, the changes in the grindability of both ulexite and colemanite related with the different structural modifications created by the heat treatment were examined with respect to work index (Wi). The effects of the heat treatment temperature and time on grindability index were also investigated. It was observed that, heat treatment significantly affected on the grindability of ulexite. The work index of original ulexite was found 7.11 kWh/shton and decreased to 3.5 kWh/shton level within 200-480°C for 60 minutes. On the other hand, the work index of original colemanite was found as 6.48 kWh/shton and no appreciable change was observed when heated up to 320°C. Thermally assisted comminution can be used to improve the grindability characteristics of ulexite. Besides, the different behaviour of ulexite and colemanite under heat treatment can be used for their separation. The artificial mixture of ulexite and colemanite could be separated with over 90% recovery by utilizing their different grindability characteristics by thermal treatment, semi-autogeneous grinding and screening.

Jan 1, 1999

By J. D. Crone

Crone Geophysics Limited in co-operation with Newmont Exploration Limited has developed a ground Pulse electromagnetic method. This is the first unit in a planned integrated system of surface and borehole Pulse EM equipment. Newmont had previously developed an operational Pulse EM unit for use in areas of very high surface conductivity. The Newmont equipment was large, heavy apparatus that required motorized transport. It operated in the equivalent frequency spectrum of 10Hz to 2.5Hz. The basic aim of Crone Geophysics was to design a Pulse EM system more portable than Newmont's. We wanted to operate in all types of field conditions including heavily wooded and mountainous terrain areas. We also wanted to record the higher frequency information that is contained in the Pulse EM waveform. There are three reasons why we thought this high frequency information was important in survey applications: (1) Field tests conducted over massive sulphide bodies in the Arizona desert showed that the desert weathering process tended to break down the electrical contact between sulphide crystals. The net effect is to reduce the conductivity of a massive sulphide body, particularly narrow bodies or highly fractured sulphide zones. In order to detect such occurances the higher frequency information is essential. (2) We wanted to be able to detect occurances with sulphide content as low as 5% sulphides that are usually poor to moderate conductors. (3) We also wanted to be able to determine the presence and extent of surficial conductive formations and clay deposits since many airborne EM anomalies are caused by such bodies. If we have the capability of detecting and recognizing these formations we would be able to explain the airborne anomaly.

Jan 1, 1976

By Y. A. Attia

A study was performed on selective flocculation and dispersion for ultrafine coal cleaning. A totally hydrophobic polymer, FR-7A, was employed as the selective flocculent for coal, sodium metaphosphate (SMP) as the general dispersant for shale and a synthetic polymeric product, polyacrylic acid-xanthate (PAAX), as the selective dispersant for pyrite. In the adsorption tests, nephelometry and spectrophotometry were employed for determining the concentration of FR-7A and PAAX in the solutions respectively. The adsorption tests indicated that: a) FR-7A has a higher affinity toward coal and pyrite than that for shale; and b) PAAX has a much higher affinity toward pyrite than toward coal and shale. In the selective flocculation tests, the ash-forming minerals can be efficiently rejected using sedimentation as the separation method. However, due to their relatively high specific gravity, pyrite particles co-settle with the coal flocs. To reject fine pyrite, a froth flotation was used for floc separation. The one-step flocculation-flotation process could reject more than 70% of each of the pyritic sulfur and ash minerals, while recovering more than 85% of the coal.

Jan 1, 1990

By J. Marbeau

In this paper, a geostatistical study of the North Butte roll type uranium deposit is presented. The geostatistical procedure applied takes into account the varying direction of the roll front for reserves calculations. For variogram calculation, the roll front is unfolded thereby allowing estimation of the variogram in directions parallel to and perpendicular to the roll front. Variograms calculated in unfolded space show strong directional anisotropies consistent with the anticipated configuration of the deposit.

Jan 1, 1991

By H. M. Breza

Recovery of phosphate concentrate has received increased attention as the existing mine and plant production capacity limitations of the Texasgulf Inc. Aurora, North Carolina Mine are reached. Improved mining techniques and mineral processing of waste streams offer a potential to increase overall phosphate production without major expansion of the Mining facility. Innovative processes have been or are being identified to maximize pit mining recovery and to minimize losses in waste streams, resulting in more effective use of the valuable phosphate natural resource. This paper will describe the various continuous recovery improvement programs being implemented to achieve this goal.

Jan 1, 1994

By W. Miola

The MSHA prescribed method for the determination of quartz in airborne respirable dust samples from underground coal mines is the P-7 method, a combination of low temperature radio-frequency ashing (LTA) and infrared analysis (lR). There is no prescribed procedure for quartz analysis in bulk samples of coal and host rock. Dispersive Infrared (IR), Fourier-transform Infrared (FTIR), and X-Ray Diffraction (XRD) methods are most commonly used for quartz analysis in powders. Several aspects of the experimental procedures such as the analysis sample preparation from bulk samples, ashing techniques, scanning procedures, peak measurement location, calibration techniques, sample amounts, size consist, and data interpretation affect differently the results from each of the methods. Significant differences in analysis results from X-ray diffraction (XRD) and infrared spectroscopy (IR) on the same samples are reported. All these studies point to the need for reliable quartz analysis methods. In a recent research, a procedure for preparing bulk coal and host rock samples for quantitative quartz analysis was developed. Further the results from X-ray diffractometry and infrared spectroscopy for quartz content on identical samples were compared. Calibrations with pure and mixed standards were used to assess the influence of particle size distribution, matrix, and calibration on analysis results. In this paper, several issues with the measurement of quartz in the samples of coal, host rock, and airborne respirable dust from mines are outlined and quantified.

Jan 1, 1994

By T. Dlokweni, A. Z. Toper, A. P. Squelch, R. G. Gürtunca

A collaborative research programme called 'DEEPMINE' was established in 1998 to investigate and research the problems of mining below three and five kilometres depths. Backfill is considered as an important support strategy to alleviate rockburst and rockfall problems in current depths and it will even become a more crucial mining strategy at ultra-deep level mining. In this paper, the evaluation and the application of the current backfill design criteria to the ultra-deep level mining environment are studied and a new backfill design criteria is proposed. The new criteria suggests that backfill should still be placed 60 - 70% of the area mined with a maximum fill to face distance of three metres. Furthermore, the vertical stress generated in backfill should be between 2 - 3 MPa at maximum 25 metres from the face at a corresponding strain value of maximum 10%.

Jan 1, 2001

By Elżbieta Węglińska, Andrzej Leśniak

The earthquake locations are generally scattered mainly due to a simplified velocity model or seismic event picking errors. The aim of our research was to increase the resolution of the cloud of microseismic events recorded during mining activity in the Bobrek hard coal mine on the 3/503 coalface to delineate seismically active structures using unsupervised machine learning algorithms. We presented results of applying two completely different algorithms for reducing scatter in microseismic location to all events recorded during mining activity on the coalface - the collapsing (proposed by Jones and Stewart in 1997) and condensation (proposed by Kamer in 2015). The collapsing method simplifies the seismic cloud by shifting events inside their error ellipsoids towards local source densities. The error ellipsoids are determined by errors in the measured parameters and seismic network configuration. The advantage of the collapsing method is the partial elimination of blurring of the microseismic cloud. The condensation method reduces the size of the set of seismic events without changing the geometrical information. The reduction of the number of seismic events in the catalog takes place through the condensation of localized events with larger uncertainty into events with lower uncertainty. The spatio-temporal analysis of microseismic events was performed separately on two processed clouds – collapsed and condensed one. We examined how collapsing and condensation methods affect the automatic detection of clusters of microseismicity using density-based spatial clustering of application with noise algorithms. We compared structures detected by the machine learning algorithms in both seismic clouds first created by collapsing and second by the condensation. We identified structures created by mining activity and structures related to the local tectonics activated by mining. The presented results are essential for the prediction of future tremors induced by the mining operation and tectonics and thus ensuring safety in the mine.

Apr 26, 2022

By Gary W. Hausler

Bergbau AG Niederrhein, a subsidiary of Ruhrkohle AG; Essen, Germany, is working coal mines on both sides of the Rhine River. The Prosper Mine in the City of Bottrop has a production of about 13,000 tons per day and has been in operation since the turn of the century. Mining has moved to the north as coal deposits south of Bottrop are exhausted. To facilitate ventilation, material handling, and transportation new shafts are being constructed in the northern coal fields. The Prosper 10 shaft is being sunk to develop the Prosper - Haniel coal field which has reserves of 280 million tons. In October, 1976 Bergbau AG Niederrhein awarded the shaft sinking contract for the 1047 m deep, 8 m inside diameter Prosper 10 shaft to Gewerkschaft Walter; Essen, Germany. Construction costs will amount to about 40 million DM with construction completion scheduled for 1981. GEOLOGY The shaft, located near the town of Kirchhellen north Bottrop, is being sunk in the Grafenwalder Horst between two faults on the south west flank of the Kirchheller Anticline. 270 m of upper cretaceus sands and marls overlay sandstone bedrock at the shaft location. The upper 124 m of this section contain highly saturated sands interspersed with marl. In order to successfully sink the shaft through this section, ground stabilization by freezing was used.

Jan 1, 1979

By T. E. Wilson

The length of Alaska's coastline, combined with the presence of a significant number of fjords, encourages consideration of marine disposal of mine tailings. However, the decision-making process is complex because various factors govern the viability of the submarine tailings disposal (STD) option. An expert system, called the Submarine Tailings Disposal Expert System (STADES), was developed to help mining project planners explore the feasibility of STD. A review of the existing literature, supplemented by engineering recommendations, on the various aspects of the marine disposal of tailings formed the knowledge base for the expert system. The shell used to develop the expert system was LEVELS.

Jan 1, 2003

By William J. Miles

From a historical perspective, bentonite is the common rock term for various uses and applications. Its name originates from water-based muds near Fort Benton used for lubrication of wagon wheels during the 19th century migration to western territories (which are presently part of the United States) when the pioneers ran out of axle grease. From a clay mineralogy perspective, bentonite is composed primarily of montmorillonite, an expandable magnesium aluminum silicate clay mineral. When magnesium occupies an octahedral structural site that usually contains an aluminum atom, a negative charge is created. In order to neutralize negative charges, cations are drawn to the interlayer surfaces between clay mineral sheet structures. Modem applications for bentonite depend on the sodium or calcium cation populations and other characteristics of the clay mineral. When sodium is the dominant cation, the material is called sodium bentonite, also known as swelling bentonite, western bentonite or Wyoming bentonite. When calcium or magnesium is the dominant cation, the material is called calcium bentonite, also known as non-swelling bentonite w southern bentonite.

Jan 1, 2012

By Mohamed A. Younis, Robert J. F. Goodfellow

This paper investigates the design approaches taken and the philosophy employed during the construction of the Metropolitan Airport Commission (MAC) storm tunnels, part of the Phase 4 Segment of the MAC Trunk Storm Sewer Project at Minneapolis St.-Paul International Airport, located in Minneapolis, Minnesota. URS Corporation was retained to provide a design and Construction Management (CM)services for the MAC Trunk Storm Sewer Project. A case history of the design and construction challenges of the project is presented. The MAC storm tunnels consisted of the construction of twin 10-foot inside diameter (I.D.) tunnels within 7 feet of an existing 72-inch I.D. storm pipe at the base of a 70-foot high highway embankment. The analysis required during the design stage of the project is discussed. This analysis and our design approach provided a defensible framework and justification to make design decisions on relevant issues including: allowable spacing of new and existing structures; preferred order of construction; expected ground deformation behavior; response of lining types to adjacent construction; and effects of proposed changes to design at the submittal stage and during construction.

Jan 1, 2003