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By Gerrit V. R. Goodman, Charles D. Taylor

A technique was developed to determine the fraction of air recirculated from the scrubber exhaust toward the face and the fraction of gas captured by the scrubber. To determine these two values, a series of tests was required. In the first test, gas was released at the face area and concentrations measured at the scrubber exhaust. In the second test, gas was released directly into the scrubber with concentrations again measured in the scrubber exhaust. The simultaneous solution of two independent flow expressions gave values of recirculation and scrubber capture. A series of tests was conducted with various combinations of scrubber flow, curtain flow, setback distance, and machine location. Statistical analyses then were conducted to determine those factors which influenced the levels of scrubber recirculation and scrubber capture in a deep cut. INTRODUCTION As cutting depths increase, the trend is toward the use of blowing face ventilation systems. With these ventilation systems, the potential exists for recirculation between the scrubber exhaust and the intake air stream. One concern is that methane gas, having been removed from the face area, is subsequently recirculated back into the intake airflow. Under these conditions, methane-laden air could be substituted for fresh intake air, leading to increased methane concentrations at the face. There is currently no standard for recirculation between the scrubber and intake airflows. The implied understanding of the Mine Safety and Health Administration (MSHA) is, and has always been, that any recirculation of ventilation air is unacceptable. To minimize recirculation potential, MSHA suggests that operators maintain scrubber and curtain flows within 0.47 m3/sec (1000 cfm) of each other. Given that recirculation may occur in some circumstances, the question arises as to how much recirculation constitutes a hazard for the face workers. Unfortunately, there is currently insufficient information to answer this. Emphasis must instead be placed on means to quantify the amount of recirculation between the scrubber and face area. Methods must also be examined to control this phenomenon. This paper presents a technique for quantifying recirculation and scrubber capture levels in a blowing face ventilation system. Several ventilation parameters are investigated to determine their effects on these levels. DEVELOPMENT OF RECIRCULATION EXPRESSIONS One way to measure airflow quantities at a point near the face would be to measure the gas flow rate Qgas, and gas concentration c at that location. The airflow Qair, would be simply the ratio of these two values, Qair, = Qgas/c. Although gas concentration values, c, can be obtained easily with existing gas monitoring equipment, it is more difficult to obtain gas flow readings, Qgas, at specific locations. To obtain these values of Qgas, another method was needed. Previous work in this area was conducted by Kissell and Bielicki (1975). However, the calculations in their model assumed a constant gas concentration in the region around the continuous miner. In a deep cut, it is questionable that gas concentrations would remain constant or uniform around the mining machine. The technique presented here does not rely on this assumption. It instead assumes that the gas concentration in the scrubber exhaust remains constant. A quantity of gas released at the cutting face either flows into the scrubber inlets or bypasses the inlets and flows around the off-curtain side (in this example, the right side) of the continuous miner (Figure 1). The fraction of the face gas that flows

Jan 1, 1993

By D. R. Zeni

Today's mine development requires the safe, expedient and economical construction of vertical shafts for both ventilation and access. This construction must be accomplished within diverse ground conditions. Advancements in large-diameter shaft drilling have led to many exceptional mechanical refinements in shaft-drilling technology. The author traces the history of the equipment and methods employed by the large-diameter shaft-drilling industry and explores the likely paths of future development. Case histories that illustrate the adaptability of shaft drilling as a versatile tool for advanced, worldwide mining operations are cited. Safety, scheduling, costs, environmental impacts and capabilities are discussed.

Jan 1, 1996

By B. K. Mishra, R. K. Rajamani, R. Venugopal, P. Songfack

Millsoft is a computer-simulation software that predicts the performance of large industrial grinding mills. This software surpasses all other tumbling-mill analysis techniques available today because it is based on fundamental laws of physics instead of empirical correlations. Graphical user interface (GUI) forms simplify the specification of the following design and operating parameters: mill diameter, length, speed, charge density and size distribution, lifter material and geometry. All of these parameters are taken into account in the discrete element numerical technique that constitutes the essence of the simulation software. In turn, the software produces a visual animation of grinding-charge motion, predicts mill power and gives the distribution of impact energy. In this paper, a case study of an 8.5-m-(28 ft-) diam SAG mill is used to illustrate the application of Millsoft for mill design and trouble shooting.

Jan 1, 2000

By D. M. Larsen, N. D. King

Since start-up in 1985, the Cannon Mine has produced and shipped a 170-g/ton (5 oz/ton) gold flotation concentrate to various smelters for gold and silver recovery. Several processes have been investigated to economically produce dore' at the mine site from the refractory concentrate. This paper describes laboratory and pilot scale test work used in the process design and engineering feasibility study of a 73-t/d (80 stpd) pressure oxidation and carbon-in-leach (CIL) facility. The designed pressure oxidation circuit utilizes a series of vertical autoclave units operating at 170°C (338°F) and 1.4 MPa (200 psig). Projected operating costs are discussed.

Jan 1, 1994

By S. Tuylu, D. Adiguzel, A. Bascetin

"Optimization techniques are successfully used in many different fields such as engineering, physics, economy, and politics in order to enhance the performance of the systems. In concrete technology, Aggregates are prepared by mixing the water and cement in proportional quantities. In order to obtain desired quality control parameters, the determination of the ingredients ratios is one of the important problems for the optimization. Additionally, in the quarries where the aggregate quality constantly changes, blending optimization must be made to obtain a sustainable aggregate quality. This study showed that linear programming, which is easy and which includes many aggregate properties, cannot be used in terms of some aggregate properties. Therefore techniques such as nonlinear programming or genetic algorithm must be used. INTRODUCTION Concrete is a used construction material and made by mixing the aggregate, cement, and water. The concrete properties are directly related to the properties of these materials in blending. The quantity of aggregates in concrete is approximately 70 percent of the concrete’s volume. Therefore, the most important material is aggregates. The extraction of aggregate materials in quarries is more problematic because of variable bedrock properties. Therefore, the quality of the materials changes and the characteristics of the concrete are also influenced directly. In terms of sustainable use of natural resources, produced aggregate materials which have different qualities should be used optimally (Adiguzel et al., 2014). Nowadays, in the solution of the blending optimization, various optimization techniques are being used such as linear programming, nonlinear programming, and genetic algorithm. In this study, blending optimization techniques especially used for concrete aggregates blending have been summarized, and the advantages and disadvantages of these techniques have been introduced. BLENDING PROBLEMS Blending is a frequently encountered problem in process-type manufacturing such as mining, refinery, food industry, chemical industry and metal industry (Sakalli 2010). Blending is a commonly used method in lots of practical solutions (Sarker and Newton 2008). Several optimization techniques are available for blending problems (Furman and Pardalos 2009). The most important issue is to blend with minimum cost. The blending problem is a special linear model which was developed to solve this problem. In blending optimization research, linear programming is a widely used method (Adiguzel et al. 2011; Bascetin and Adiguzel 2011)."

Jan 1, 2016

By L. Yuan, J. H. Rowland, R. A. Thomas

"Hydrogen (H2) gas released during battery charging can result in cross-interference for carbon monoxide (CO) sensors used for early fire detection and compromise the integrity of the mine atmospheric monitoring system (AMS). In this study, a series of laboratory-scale and full-scale experiments were conducted to evaluate the responses of different CO sensors to H2 gas. In the laboratory-scale experiments, constant H2 concentrations in the airflow, from 100 to 500 ppm, pass through sensors. While in the full-scale experiments, increasing H2 concentrations generated as a byproduct from charging the batteries at the battery charging station rise to the sensors under different ventilation scenarios. The H2 concentrations at the CO sensor location were measured using H2 sensors and were correlated with the CO sensor response. The effects of ventilation and sensor location on the CO sensors responses were also analyzed. The results of this study can help mining companies to select appropriate CO sensors and improve the deployment of these sensors to ensure the safeguard of underground miners. INTRODUCTION As many types of battery-powered mining equipment such as scoops and shield haulers are used in underground mining operations, charging stations are required to charge the equipment batteries. These batteries are of lead acid chemistry. A safety issue exists with the battery charging stations as all lead acid batteries produce flammable H2 gas during the normal charging process. Overcharging or excessive heat can quickly cause batteries to produce even more H2. If H2 is not appropriately diluted or dispersed, it builds up, and the risk of fire and explosion increases. Mine Safety and Health Administration (MSHA) regulation (30 CFR Part 75.340) requires that battery charging stations should be housed in noncombustible structures or be equipped with a fire suppression system. When a fire suppression system is used, the battery charging stations must be ventilated with intake air that is directed into a return air course or ventilated with intake air that is monitored for CO or smoke using an AMS. The monitoring of intake air ventilating battery charging stations should be done with sensors that are not affected by H2."

Jan 1, 2018

By E. M. R. Santos

Acid mine drainage (AMD) is a serious environmental problem in mining activities. Prediction is the first step for evaluate the potential of acid generation and there are some possible methods to estimate it. They are described as static tests, which examine the balance between acid producing and acid consuming materials, and kinetic tests, which attempt to predict drainage quality over time. Static methods are very simple and give a qualitative classification of the ores based on their potential to generate acid drainage. The characterization of ores to determine their acid producing potential is vital for the prevention of long term environmental liabilities. Laboratory tests were conducted under different methodologies to predict the acid producing potential of sulphide overburden, ore materials and tailings from a deposit of copper ore.

Jan 1, 1999

By Mucella Ersoy, Nese Celebi

Management Information System (MIS), is a system using formalised procedures to provide management with appropriate information to make timely and effective decisions. Before developing MIS, first functions of the organisation should be defined and grouped into subsystems. After determining the information required and produced by each system and interaction between subsystems, the related data resources should be structured into a series of databases and files. In this study, the MIS developed for Soma Open Pit Mines, Turkey is described in this respect. First, analyses of the existing system including user requirements and scope of the system are given. Then the designed information system, its subsystems, interaction between subsystems and system structure are presented in detail.

Jan 1, 2002

By J. W. Rold

In 1973 housing and construction conflicts threatened Front Range gravel resources. The legislature addressed the problem by passing HB 1529, which required the Colorado Geological Survey to map the deposits and forbid local governments to change lands over commercial mineral deposits from zones allowing mineral development to zoning which conflicted with development. It charged counties to develop Master Plans for Extraction. Plans must consider resource quality, multiple-sequential-use potential, surrounding area compatibility, neighbors, quality of Life, extraction maximization and reclamation potential. Imprecisely worded statutes, budgetary constraints, lack of enforcement and political pressures have limited benefits from the law.

Jan 1, 1987

By Norbert Patzelt

The high-pressure grinding roll was introduced about 10 years ago and has established itself in many applications. Most of these machines are used in grinding circuits in the cement industry. A few operate in conventional mineral-processing plants. Polysius has sold more than 350 Polycoms worldwide. An exception is diamond-ore processing in South Africa and Australia. This type of grinding system increases diamond liberation and reduces the capital costs for the downstream processing plant. There are several reasons why high-pressure grinding rolls have not been used more extensively in the mining industry: - The mining industry adheres to conventional grinding technology and regional preference for certain comminution circuits. - Design, scale-up and flowsheet assessment procedures are viewed as being immature and reduce confidence in the potential application of the technology. - Downstream process benefits are unproven on a plant scale.

Jan 1, 1995

By L. L. Lien

In this economic age of high interest rates and softening mineral commodity markets, the mining industry is taking a hard look at how it conducts its business and where economies can be effected. The capital investment to build a new metallurgical facility or open a new property has traditionally attracted substantial investigation, analysis and management attention. The areas of mineral exploitation, financial feasibility, engineering and construction have been studied extensively and their management, although still difficult, have become refined disciplines.

Jan 1, 1982

By Stephen J. Crittenden

Deep gas and oil production has been substantially increased over prolonged periods through the use of sintered bauxite propping agents. Since its inception in 1976, over 170,000,000 pounds of high strength ceramic proppants have been employed. Recent field evaluations and economic analysis demonstrate the superiority of sintered bauxite proppant over quartz sand. This paper describes the development, application, field results, and product evolution of sintered bauxite.

Jan 1, 1983

By Tzou-Shin Ueng

Rock reinforcement of rock anchors and rock bolts are commonly used for the support of large rock caverns. The rocks at the location of most large underground openings are usually under very high initial stresses prior to excavation. Hence, the stress redistribution caused by excavation will induce considerable rebound deformations of rocks surrounding the caverns. Since the pressures exerted by the reinforcement are generally far below the initial rock stresses, the reinforcement will be stretched along with the rock deformations, and the stresses in the reinforcement increase accordingly. It is not uncommon for the stress in the reinforcement to reach the yield strength, and in some cases the reinforcement may even have failed. Therefore, the increase of stresses caused by the rebound deformations of rocks should be taken into account in addition to the force required to stabilize the caverns. It was found that the measured stress increases of the prestressed tendons after installation were in good agreement with those computed based on the measured rock deformations between surface and the anchoring point of the reinforcement. The rebound rock deformations and the stress increases in the reinforcement can be estimated based on the results of the finite element analysis and experiences in previous field measurements incorporated with considerations of the geologic conditions, rock properties, rock reinforcement and construction procedures.

Jan 1, 1986

By M. Poulton

Backpropagation, learning vector quantization, counterpropagation, functional link, probabilistic, and. self -organizing map are among the most popular neural network classification paradigms. Each paradigm finds a unique set of weights that will map the input pixels into their respective output classes. The usefulness of each network depends on its overall accuracy, ease of use, speed and scaling. The fastest and most accurate networks in this study were the functional link and counterpropagation. These networks, however, do not scale well to large input vectors or large training sets. A better choice is the LVQ network which achieves high accuracy, is fast, requires a minimum number of input parameters and presents fewer scaling problems.

Jan 1, 1992

By Raj K. Singhal

Three principal activities are involved in planning and developing a surface mine. These are 1) definition of economic and technical feasibility, 2) design, procurement and construction, and 3) mining and reclamation. The last is the only activity which begins in the feasibility study and continues throughout the life of a mine. It is also the activity which depends heavily on use of computers. This paper deals with a method of selecting mining software and dwells on the recent progress, made in this area. Discussed also is the status of computerized equipment management and information systems: a microprocessor based technology applied to dispatch systems, monitoring of equipment health and performance, wireless data transmission to a centralized data processing unit, and mine- wide information and reporting system. Reference has been made to upcoming developments which offer the potential- of transforming the surface mine of the year 2000 into a "manless pit". Canadian achievements in all of these areas have been highlighted at appropriate places in the text.

Jan 1, 1989

By K. N. (Mani) Subramanian

A 2.5 meter diameter column has been successfully used in a 100 tph flotation plant at the Harbour Lights Mine in Leonora, Western Australia, to produce a final gold bearing sulfide concentrate from the ore in a single stage. This pioneering application of column flotation cells to rougher stage was pilot tested using a 11 cm column, which demonstrated column's capability in rougher, scavenger and cleaner flotation stages. A hybrid circuit involving columns and mechanically agitated flotation cell s was adopted for the commercial installation. This paper describes pilot plant results, design of the plant flotation circuit, and early results of commercial operation.

Jan 1, 1988

By B. J. Scheiner

The presence of organic materials in gold ores cyanidation. The presence of organic materials interferes with gold extraction by The carbon contained in the ore has been shown to adsorb gold cyanide complex from solution. Removal of the carbon content by roasting or chemical oxidation prior to cyanidation results in gold extractions of 85 to 95 pct. This paper by the Bureau of Mines, U.S. Department of the Interior, discusses how the mineralogy of the carbonaceous gold ores affects gold recovery by cyanidation. It also discusses the advantages and disadvantages of roasting and chemical treatment to render the ore amenable to cyanidation.

Jan 1, 1987

By John A. Herbst, K. Rajamani

Process improvement is probably the most widespread objective of mineral process plant operators in the late 1980's. An important part of such improvements is dynamic optimization which involves reacting to inevitable plant disturbances in such a way that productivity is maximized at every instant of time. This paper describes the way in which mathematical models can be and have been used in dynamic optimization. Both off-line and on-line model applications are described.

Jan 1, 1989

By F. G. Miller, M. Polat, S. Chander

Flotation was used to achieve improved separation of magnetite from the float and sink products obtained from heavy medium separation and to reduce the load of the medium cleaning circuit. The investigation was carried out in two successive phases. In the first phase, tests were performed on in-plant samples from the Homer City Coal Perdition plant to determine what effects variables such as medium density, particle size and magnetite source had on the efficiency of the process. In the second phase, the optimum conditions determined in the first phase were used to determine the applicability of the process to other selected coals from central Pennsylvania. It was observed that flotation was very effective in the separation of magnetite from coal. In most of the cases investigated, the magnetite recovery was approximately 99% with a magnetite grade ranging from 95 to 99%. The grade of the magnetite decreased as the ash content of the coal increased and the particle size of the magnetite decreased.

Jan 1, 1994

By Vi-Duong Dang

Lithium requirements in the next few decades for batteries and controlled thermonuclear fusion reactors (CTR) may exceed the availability of the current mineral and brine reserves. It is thus prudent to search for new reserves and resources to satisfy these and future lithium applications. The lithium content of the waters from the Smackover oil field. located in the Gulf Coast region of the United States, ranges from 100 to 500 mp/l and could represent a substantial new reserve. Experimental evidence described in the literature indicates that a specific chelating agent dipivaloylmethane (DPM), of the diketone type, has a specific selectivity toward lithium in the presence of other metal ions in aqueous solutions. Based in part on this unique property of dipivaloylmethane, a conceptual design of a full-size plant to extract lithium from the Smackover brine is presented in this paper. This study includes alternate flow-sheet development, design information on the major units of the process, energy requirements, and an economic analysis of a facility capable of producing 106 kg of lithium per year. The economics of three different process concepts depend primarily on the amount of water needing to be evaporated from the initial oil-field feed waters in concentrating the brine. The results, as a function of production rates, are indicated only in a general manner.

Jan 1, 1978