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By J. A. Bradbury

N. A. Degerstrom, Inc. has constructed and operated a processing plant approximately five miles north of Soda Springs, Idaho for processing a byproduct phosphate treater dust from Monsanto's elemental phosphorus plant, also located in Soda Springs. The plant is designed to produce agricultural-grade phosphoric acid, gallium, and silver. The design capacity of the plant is 54.4t (60 st) of treater dust per day, which can produce 16,326t (18,000 st) of phosphoric acid, 6,600 kg of gallium, and 6,033 kg (194,000 oz.) of silver per year.

Jan 1, 1993

By M. Falutsu

"The PSI-200 is a rugged, innovative, and easy to install on-stream size analyzer. Its calibration is simple and can be done on-line, during operation. Two measurements are displayed on the panel, which are expressed as percent passing a selected size, or as any statistical diameter. These two measurements are given as two continuous 4-20 mA output signals. Operation alarms are displayed on the screen or are given as digital output signals.The PSI-200 has been used in various applications at Lakefield Research. Particle sizes ranging from 10 µm to 450 µm have been monitored successfully, with an accuracy of 1- 2%. Having the size measured continuously and reliably, optimum conditions have been established for the grinding circuit, resulting in a superior quality in pilot plant testing.INTRODUCTIONThe challenge of any operating plant is to optimize product quality, maximize throughput and minimize operating costs. The importance of particle size measurement at a grinding circuit is well recognized. Monitoring continuously the particle size and keeping the product as uniform as possible is crucial to the whole mill operation regardless of the nature of the operation.Various techniques and instruments have been developed over the years attempting to give reliable on-line size analysis data. The operating difficulties and the reliability of these equipment still present major drawbacks and none of them proved to be widely accepted.PSI-200 is a relatively new on-line analyzer. The operation is simple and of low cost and the maintenance required minimal. It measures particle size and it displays two parameters of the solids size distribution, either weight fraction of passing a certain size or any statistical diameter. Two analog outputs can be sent to a process control system and through a supervisory control loop the correct action can be taken to maintain the desired particle size (perhaps adjust the feed rate to the grinding mill)."

Jan 1, 1993

By Thomas J. Peters

The King Mountain study area is centered about 120 air km northwest of Blackfoot, and 30 air km north of Arco, Idaho. The study area makes up the southern one-third of the northwest-trending Lost River Range--the highest mountain range in Idaho. The area is predominantly underlain by Paleozoic-age marine limestone and lesser dolostone, with a relatively small inlier of silica-rich, Ordovician-age quartzite. There are vast, unquantified resources of these industrial minerals present; however, special markets need to be developed for these resources which are near enough for transportation costs to be competitive. Five prospects were found in the study area; however, only one, the Elbow quartz silica prospect, contains resources and current claims. There has been no mineral production in the study area.

Jan 1, 1993

By Bruce W. Cavender

In an effort to lower production costs and improve profitability, mining companies have adopted a variety of management practices emphasizing productivity and cost containment. One set of practices that has been used successfully in the manufacturing and electronics industries is "world-class manufacturing" (WCM). It is applicable to mining as well. World-class manufacturing is based on the twin concepts of "just-in-time" inventory practices and total quality control. A few mining companies have implemented quality control programs that are similar to WCM in some ways and substantially different in others. This article considers the use of WCM in the processing environment, although the techniques are applicable throughout a mining operation. The article is also mindful of the variety of customers to whom mineral products are sold. Industrial minerals producers may sell brand-name products to specific customers with exacting requirements, while metals producers often sell their fungible output on a faceless commodity market. Customer requirements are emphasized in WCM, and so the range of these requirements must be recognized. World-class manufacturing In any milling process, specific goals are set for product and process characteristics - concentrate grades, minimum daily throughput, moisture content, etc. WCM has two overriding objectives: the reduction of deviation from these standards, and the reduction of variability in all aspects of the process and product. By definition, reduction of deviation also includes minimizing plant downtime for repairs or process changes. WCM plants use just-in-time inventory practices and total quality control. WCM plants use these techniques to simultaneously improve productivity and reduce costs.

Jan 1, 1993

Evaluation of reserves on a production scale within a shear-hosted gold deposit is complicated by the nature of the mineralisation itself. The 'payable' ground seems to be confined to areas with intense shearing, while the remainder of the deposit is characterised by 'background' mineralisation at a very low level.

Jan 1, 1993

By R. V. Ramani

One area of study in the Coal Mine Injury Analysis project was to illustrate and enhance the ability of mine safety management personnel to apply analytical techniques to injury experience data and to justify requests for funds for safety enhancement actions on a cost/benefit and other quantitative basis. Four volumes of this final project report detail (1) the objectives and scope of the mine safety management research, (2) the results of literature review, and case studies, and (3) models developed for mine safety management. The four volumes are titled as Volume III: Mine Safety Management, Volume IV: Analytical Techniques for Mine Safety Management; Volume V: Mine Safety Management Case Studies and Volume IX: Training Cost Model. This volume deals with the development of a microcomputer based training cost model (TCM) which can be used to analyze training cost implications of various types of training. The model has been developed using Aston Tate's dBASE III plus language. The computer program and a test run of the model are presented in this report.

Jan 1, 1993

By Thomas E. McNider

On July 20, 1990, a Spontaneous Combustion Control Plan was approved by MSHA for Jim Walter Resources, Inc. No. 5 Mine. The mine operated under the plan for twenty-nine shifts before MSHA revoked the plan. A total of fifty-five seals were constructed during the process of implementing the plan. The major difficulty in applying the control concept resulted from problems controlling leakage at the numerous seals. The number of seals was a direct consequence of attempting to merge the traditional bleeder system, used in all the Blue Creek Mines, with the bleederless system Jim Walter Resources proposed as a means of controlling the spontaneous combustion hazard. This paper discusses Jim Walter Resources experience with spontaneous combustion control and the new safety standard which applies to underground coal mines that demonstrate a history of spontaneous combustion and how this standard would apply to our No. 5 Mine. The new Ventilation Standards were published in the Federal Register on May 15, 1992, and scheduled to go into effect August 16, 1992.

Jan 1, 1993

By John R. Goode

The fist part of this paper comprises a general discussion on refractory gold ores and their mineralogy. Processing methods now in use are reviewed and test procedures for the important methods are discussed. Factors determining the selection of a process are outlined. The paper includes a survey of production plants using pressure oxidation, roasting and biological oxidation to process refractory ore. The status of processes under development is briefly reviewed.

Jan 1, 1993

By Daniel W. H. Su

A floor-bearing capacity test apparatus was designed and constructed to determine the true bearing capacity of soft floor materials beneath coal pillars or longwall face supports. The apparatus has been employed in entries up to eleven feet in height. Results of in-mine floor-bearing capacity tests suggested that the ratio of the soft fireclay thickness to the bearing plate width and the moisture content in the fireclay were the most critical parameters affecting the ultimate bearing capacity. Foundation engineering principles were applied to interpret the field test results to estimate the floor-bearing capacity beneath longwall face supports.

Jan 1, 1993

By Michael G. Nelson

A computer simulation of the automatic control of continuous mining machines has been prepared, similar to previous simulations of longwall mining systems and coal thickness sensors. The simulation allows for programmed variation of the horizon detection method, the azimuthal guidance system, the type and configuration of the miner, varying hardness in the unmined face material (leading to varying error in the machine heading), and the miner's cutting cycle. It simulates control of the miner in three axes. Use of the simulator makes it possible to anticipate problems arising from the complex character of underground mining, which include unpredictable multi-pass coupling and unpredictable variation in geological conditions.

Jan 1, 1993

By John Turner, David Carey

The Robbins Mobile Miner demonstrates the successful combination of hard rock excavation technology and the latest electronic control technology. The mobile miner, a partial face hard rock tunneling machine, features a fully integrated control system relying on a Programmable Logic Controller (PLC). This PLC controls all functions: tramming, steering, boom swing, cutting depth, conveyor operation, air scrubbers, hopper loading and unloading, etc. The machine is fully instrumented allowing the PLC to monitor the results of all commands on a continuous basis, to record data, to evaluate developing problems, or to shut the machine down if necessary. The paper describes the development of the Robbins - Pasminco automated mobile miner and early testing at Pasminco Mining's Broken Hill Southern Operations, New South Wales, Australia.

Jan 1, 1993

By P. A. Botha

The production of iron and steel generates various types of waste materials containing oxides, carbon, and flux material. Usually, these materials are land-filled at the plant site or are hauled away for disposal. Some of these waste materials are hazardous, and they must therefore be recycled or disposed of properly. The influence of different waste materials in iron-ore sinter blends on the quality and operational parameters in sinter production is described. The recycling of waste materials such as dolochar, scrap fines, mill scale, electric-arc furnace slag, basic-oxygen-furnace mud via the sintering process can achieve a saving in the cost of the raw materials (for example, fuels and flux) and a reduction in pollution. A comparison of a typical sinter with a sinter produced through the utilization of waste materials shows a distinct correlation between certain types of waste material and some metallurgical properties and operational parameters. Dolochar (and arc-furnace slag) in a sinter blend acts as part of the fuel and flux that are normally added to a sinter mix. In general, dolochar improves the quality of the sinter and decreases the consumption of coke. Other waste materials adversely influence the quality of the sinter, but not necessarily the operational parameters such as the production rate. At Vanderbijlpark, approximately 15 kt of various waste materials per month are successfully recycled in the sinter plant. Investigations into the handling and recycling of other waste materials may indicate that even more waste materials can be utilized.

Jan 1, 1993

This paper outlines a range of strategies for steady state optimisation of most types of concentrators. Optimisation is considered in terms of comminution performance, energy efficiency, concentrator strategy and overall mine/concentrator operating philosophies. Application becomes more complex as the range of optimisation is expanded. However, the potential gains also increase. A step by step framework for data collection and analysis is provided. This process is facilitated by powerful simulation and mass balancing programs which are now in common use. Once a sound, steady state rationale for optimisation has been developed, it may be used to provide a fine foundation for process control system development.

Jan 1, 1993

By Koppe J. C

This paper describes the methodology developed to establish a sequentia mining plan applied to a coal mine, using computers. Firstly, isocontou. maps were generated from the drill holes and outcrop description information, representing the thickness and depth of the rock formation: present in the mine site. The procedure relies on the repeated application of the cross validation techniques, until the standard deviation of thi estimation is reduced to a minimum.From this map the coal reserves of the two coal seams, the overburdet (separated in hard and soft material) and the interburden were calculated After that, the maps were transferred in digital files to AutoCAI software, where different mining plan simulations were performed. 7b ore evaluation in each case was done automatically, including tonnages volumes and stripping relations. The final mine configuration consider the economic aspects of the operation.

Jan 1, 1993

By J. Hanna, J. Jung

Researchers at The University of Alabama have recently developed a two-step method for the treatment of phosphorus sludge. The process includes the bulk removal of phosphorus by physical separation techniques followed by the remediation of the residual P4 in the sludge using a novel, wet, air-oxidation technique known as "HSAD." Tests made on electric furnace, phosphorus sludge samples have demonstrated that an essentially complete and fast removal of the contained P4 can be achieved by the HSAD wet oxidation treatment. Further studies were made to determine the applicability of the two-step process to sludges of different origins, pretreatments, storage conditions and P4 contents. The present work discusses the mechanisms and factors controlling the HSAD, wet, air-oxidation remediation approach.

Jan 1, 1993

By Vincent Thorne

On January 2, 1992, the R. Zoppo Company of Stoughton, Massachusetts started drilling and blasting operations on U.S. Army Corps of Engineers Project Number: DACW33-91-B-0072 to widen and deepen the Portsmouth Harbor and Piscataqua River Navigation Channel.

Jan 1, 1993

By Karl E. Burgher

Accidental explosions occur throughout the world. They can happen at chemical plants, fireworks plants, grain depots, or as a result of collisions involving volatile or hazardous chemicals. It is interesting, as we know as blasters, that we can take two very harmless products and mix them under certain conditions and produce a violent explosion. It is often very difficult for the investigator to determine the magnitudes of blasts after the fact. However, an estimate must be made to settle vibration and airblast damage claims. The blasting consultant or technical representative is often called upon to act as an expert to mitigate these claims.

Jan 1, 1993

Using a Mark IV surface force apparatus, adsorption of dodecylamine hydrochloride on mica has been studied at pH 5.7 in the presence and absence of octanol. With amine alone, the repulsive forces between mica surfaces are reduced due to charge neutralization and attractive hydrophobic force; however, the latter is of relatively short-range with its decay length less than 2 nm. In the presence of amine and octanol, the hydrophobic force becomes more significant, its decay length being extended up to 6.5 nm. The increased hydrophobicity in the presence of octanol is attributed to the co-adsorption of the neutral surfactant with dodecylamine, which increases the packing density of hydrocarbons on the mica surface. The increased hydrophobicity due to co-adsorption is reflected in the improved floatability of silica when using octanol as an extender.

Jan 1, 1993

By Meloy TP

Several important, fundamental aspects of the grinding behaviour of mineral systems are addressed. The Levenberg-Marquardt algorithm for systems of constrained non-linear equations was used to solve the steady-state and dynamic population balance model (PBM) grinding equations to obtain the mill matrices and grinding selection and breakage rate functions, respectively. The fact that the PBM model equation Inverse Problem is degenerate or underspecified is demonstrated. Multiple solutions to the same PBM equations are provided. It is shown that there is no unique solution to the Inverse Problem unless additional constraints are provided or assumptions are made such as the Arbiter-Bhrany normalisation assumption. The severity of the non-uniqueness problem for steady state grinding is demonstrated in several examples using typical feed distributions and mill matrices. In addition, it is also demonstrated that when higher than single powers are used in steady-state mill matrix expressions during simulation or calculation (or iterative procedures are used during numerical simulation) and four or more size intervals are used considerable amount of error is propagated throughout any calculation. Each solution to a PBM, while giving the same prediction during a single mill pass, gives different solutions or predictions for mill composition upon subsequent passes. In addition, it is shown that there is a problem with building up a grinding mill knowledge base with PBMs. A similar analysis was done for the dynamic or kinetic PBM equations. The fact that the dynamic PBM Problem is degenerate or underspecified is also demonstrated. Multiple solutions to the same dynamic PBM equations are provided. Again, it is shown that there is no unique solution to the Inverse Problem unless additional constraints are provided or assumptions are made such as the normalisation assumption. Each solution to a dynamic PBM, while giving the same prediction for a given grinding time interval, gives different solutions or predictions for mill composition for other grinding times. Actual experimental grinding data was assessed to determine the functionality of mill selection and breakage functions. The functionalities obtained through constraints were compared with those obtained with the normalisation assumption of Arbiter-Bhrany which relates breakage functions to particle size distribution. The capability of the population balance model to predict grinding behavior over time in various mineral grinding systems was assessed. The required functionality of selection and breakage functions for effective prediction of grinding behavior in mineral systems is discussed.

Jan 1, 1993

The primary objective of any planning exercise is to maximise the return on funds utilised while maintaining a safe and socially responsible working environment. In order to achieve this, it is essential that the assumptions applied reflect as accurately as possible the future realisation of the project. In narrow vein mining, the risk that this will not occur can be significantly greater than that associated with other types of mining projects. This results partially because of dramatic effects upon project cash flows with seemingly minor changes in operating parameters such as orebody width and wall rock competency.The validity of a planning exercise can therefore be related to the extent of available data and to the experience and perceptions of the operating entity. The various factors which must be assessed include absolute values and variations in a range of factors, especially the dip and dimensions of the orebody, the geotechnical parameters and anticipated ground conditions, the productivity and production characteristics of the selected mining method as applied to the specific orebody, and the impact of mine access and development.

Jan 1, 1993