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By Gary Beerkircher

WaterFlush Technology and WaterFlush crushing offers significant operational ben­efits in gold milling operations. WaterFlush crushing is the technology that Nordberg Inc. has developed, tested and proven in an actual operation during the 1980's. Patents have been obtained for both the process and the apparatus of implementa­tion. WaterFlush involves volumetric process controlled water flow into the ore feed cav­ity of a WF cone crusher. While the addition of water in itself is not new, the con­trolled amount of water coupled with the WF crusher operating parameters are revolution­ary. The WF crusher is a specially designed version of Nordberg's Omnicone crusher oper­ating at higher speeds, with a reduced ec­centric throw and higher horsepower capabil­ity. The results are increased capacity, higher crushing energy input and a finer crusher product. The WF crusher product is a slurry containing 40-60% solids by weight.

Jan 1, 1990

By P. R. Altringer, R. H. Lien, B. E. Dinsdale

The Bureau of Mines, U.S. Department of the Interior, is investigating biodegradation of cyanide as a means of decommissioning heap leach operations. Biological oxidation decreased weak acid dissociable (WAD) cyanide in process solutions from 50 to 170 ppm down to 0.1 ppm. The tests were conducted both in trickling column reactors, using quartz as the growth surface, and in upflow columns, using activated carbon as the growth surface. In addition, exploratory tests indicated that bacteria will destroy residual cyanide in leached ore. A flowsheet has been proposed for closure of heap leach operations in which the metals processing portion of the plant, possibly the carbon adsorption columns, or a collection pond is used as a bioreactor. The cyanide in the process solution is destroyed in the bioreactor and the treated water is used to rinse residual cyanide from the spent heaps. The water is recycled until the effluent WAD cyanide concentratio� meets discharge standards.

Jan 1, 1992

By John E. Litz, Charles W. Kenney, Wayne Carter

Refractory gold ore pretreatment processes continue to receive much attention. This paper compares the relative economics of treating ores by oxygen pressure oxidation, roasting and bacterial oxidation with or without preconcentration by froth flotation. Capital and operating cost estimates for each method of pretreatment were prepared and these estimated costs and ore sulfide grades then are used to compare the process economics. The study indicates that the most significant item affecting the economics is the amenability of the ore to flotation. The cost benefits of flotation are $10-13 per tonne ore processed (2%-4% s=, 10:1 ratio of concentration). In most cases bacterial oxidation has the lowest overall cost, especially if less than complete oxidation of the sulfides will give acceptable recovery, however bacterial oxidation has yet to be practiced on a large scale. In all situations pressure oxidation shows the highest cost. However, the cost differences between the treatments are small, less than $7 per tonne.

Jan 1, 1990

By Stanley Bunk

The fluidized bed was invented by Fritz Winkler of Germany in 1921. The first application in the U.S. was in the development of the fluidized bed catalytic cracking of petroleum in 1942. Today, fluid bed cracking reactors are an integral part of every oil refinery. When fluid bed technology was first considered for applications outside the petroleum industry it was recognized to have uniform temperature, close control of the gaseous atmosphere and excellent mixing between solids and gases. Roasting of sulfide ores and concentrates was an obvious match. The first application was a single stage roaster for gold refining in 1947. There have been over four hundred commercial fluid bed roasters built and operated successfully in the four decades since the fluid bed was invented. There are three general categories of roasting applications. The largest number of roasters fall into the dead roasting category which includes gold ore roasters. The other categories are sulfating roasters and partial roasters (Reference 1).

Jan 1, 1990

By Gregory A. Vaka

Robins Engineers & Constructors, Inc. as the exclusive U.S. licensee introduced the PIPE CONVEYOR to the North American marketplace early in 1984. The sale of the first PIPE CONVEYOR in 1985 was a difficult task since the conventional troughed belt conveyor was the accepted and the most widely used means of continuous transportation of bulk materials handling in the world. Initially our clients viewed the PIPE CONVEYOR as a departure from the normal and accepted form of material handling. Since then, the parent company of Robins Engineers merged with Krupp of Germany to form KRUPP ROBINS, INC. in the United States. To date there are over 462 PIPE CONVEYORS operating worldwide with the majority of the long overland systems designed and installed by Krupp Robins, Inc. The PIPE CONVEYOR is now becoming the norm, viewed by those who are familiar with its capabilities as the preferred method of transportation for all bulk solids.

Jan 1, 1997

By Michael G. Strominger, Anthony E. Gross

The development of precious metals ore agglomeration with a cement binder, by the U.S. Bureau of Mines, has allowed the economical heap leaching of low grade gold ores (<0,05 oz/ton) over the last decade, Even with the Bureau of Mines technology, numerous operations continue to experience channeling and blinding problems. A research project was undertaken at Nalco Chemical to address situations where improved agglomeration is needed, By increasing the incorporation of fines into the agglomerates,the segregation of ore by size which occurs from handling will be reduced and channeling minimized. A stronger agglomerate will reduce fines migration during leaching and prevent blinding of the heap, Both of these changes will give an even flow of barren solution throughout the heap and give solution contact with all of the ore. This paper presents the development of polymeric agglomeration aid, Nalco 9760 which has given a higher rate of and a higher total gold recovery in plant evaluations.

Jan 1, 1990

By P. Whincup, T. Showell, B. Marchant, R. Dunne

An oversupply of copper on world markets in the early 90' s, coupled with a decrease in demand, resulted in a "tight" market for the sale of copper concentrate. In these conditions small producers of low grade copper concentrates found it difficult to sell their products. The situation was exacerbated for those producers also having reasonable quantities of penalty elements (e.g. As, Bi). The Telfer Gold Mine bulk copper gold concentrate, produced from treating underground sulphide ore, fell into this category (i.e. 16% to 20% copper, 30% to 35% sulphur and 3500ppm to 4500ppm arsenic). The concentrate sulphide minerals are predominately chalcocite and pyrite. Although a higher grade copper concentrate was attainable a substantial decrease in gold recovery ensued. Under the prevailing market conditions a decision was made to stockpile concentrates pending either an easing of market conditions or alternatively finding an on site method for treating the concentrate to recover both the contained gold and copper.

Jan 1, 1995

By D. W. Dew, D. M. Miller, P. C. van Aswegen

The bacterial oxidation (BIOX®) process for pre-treatment of refractory ores for gold recovery is marketed by BIOMIN Technologies S.A. The process was originally developed by GENMIN who are still providing testwork, design and commissioning assistance to BIOMIN. This process offers an alternative to the more conventional roasting or pressure oxidation techniques with the following advantages: • Greatly reduced capital costs for small to medium size plants. • A relatively flexible and easily controllable process requiring relatively unskilled labour for operation. • Improved gold recovery. • A process that is environmentally friendly. The principal disadvantage of bacterial oxidation is the relatively slow kinetics compared to pressure oxidation and roasting, a plant residence time of 4 to 5 days typically being required to obtain complete liberation of gold from refractory sulphide minerals. Bacterial activity is also slow to recover from disruptions such as air supply failure or contamination by toxic species such as cyanide. Optimum plant performance depends on judicious management and sound training of operators.

Jan 1, 1993

By Richard A. Hunnisett

Silica sand is one of the world&apos;s most plentiful resources and is a basic necessity in our way of life. The end uses of silica sand are an integral part of our homes, transportation, and places of work. The environmental legislation enacted in the early 1970&apos;s, coupled with the oil embargo and higher than normal inflation, have had a very real impact on the industry and its primary consumers, the foundries and glass producers. The present environmental laws directed at air and water pollution and the working environment can, in most cases, be met, but not without large capital expenditures for equipment. These expenditures must reduce the funds available for expansion and modernization of existing processes which are necessary if the costs to produce industrial sand are to remain at acceptable levels. The concern for the future is the enactment of more stringent laws, and the available technology and equipment to economically comply with them.

Jan 1, 1978

By P. Anciaux, T. Simpson

The competitiveness of the EU manufacturing industry has come to the forefront of EU politics. The systematic monitoring of developments and the review of the state of the competitiveness of economies and enterprises was identified as an essential component in this process. Work is currently being carried out within Enterprise and Industry Directorate-General in order to analyse the different factors that influence the competitiveness of the non-energy extractive industry. Such an assessment should help to identify policies and actions which could contribute to and enhance the competitiveness of the industry. Assessing the competitiveness and sustainability of the industry implies the need for reliable, consistent data. One important example of how this need is being addressed, is the development of sustainable development indicators (SDI) for the EU non-energy extractive industry. These seek to monitor the industry’s performance and provide a platform for openness and discussion. Work was started on the development of SDIs in 2000, and the first report was published in February 2004.

Jan 1, 2005

By Yuting Xue, Xin Li, Ihsan Berk Tulu, Gaobo Zhao, Deniz Tuncay, Mindi Ruan

Most coal mine roofs in the Appalachian region consist of laminated shale, which is prone to brittle failure. Accurate modeling of shale roofs is vital for studying cutter failures of these shale roofs, and ordinary and formational bedding planes play a significant role in the response off the shale roof to mining-induced stresses. This paper presents a robust method for constructing three-dimensional shale roof models using limited borehole cores and leveraging image processing techniques. The approach begins with image extraction from shale cores. Then, we extract the portions that feature the core and employ image-stitching techniques to merge them seamlessly. Once the images are stitched, they are duplicated horizontally and merged to create a cross-sectional plane image representing a shale roof. This roof cross-sectional plane image serves as an input to our proprietary Digital Image Processing (DIP) algorithm, which is adept at extracting ordinary bedding planes (interfaces that represent color transitions between a single shale unit). The extraction process involves transforming discrete core points (ordinary bedding plane pixels) into continuous lines representing ordinary bedding planes. Finally, extending this method into the third dimension, the model is further extrapolated to form a comprehensive three-dimensional shale roof. Through this process, the geometry information of ordinary bedding planes can be extracted for each type of shale in cores, including sandy shale, gray shale, dark shale, etc. This work bridges the gap between limited core data and comprehensive 3D geological modeling, offering valuable insights into identifying and quantifying the variations in different shale roof geologies.

Jun 25, 2024

By R. K. Singhal, D. B. Stewart

A variety of equipment is being used for roadheading and tunneling in the mining industry. In United States drum-type continuous miners are used most extensively. In Europe and Canada mine roadways are driven mainly by roadheaders. The application of tunnel boring machines to coal mining is somewhat recent. Such machines are however being used on major projects driving main mine entries.

Jan 1, 1985

By Stephen P. Winkelmann

The expansion of gold production in Nevada&apos;s Carlin Trend over the last few years has been staggering. To increase gold production while minimizing capital requirements and providing for the safe and efficient mining and processing of ores has required a tremendous effort by the mine engineering group at Newmont Gold. Organizational changes were implemented by the company to effectively deal with a full range of engineering problems. Specially developed computer software and its applications will be explained in this article as well as improvements in the techniques used in converting geologic resources into reserves. Scheduling procedures for the mining of multiple pits to feed multiple processing facilities will likewise be presented. Ore control procedures and current mine engineering practices are discussed. Growth at Newmont Gold Expansion of production levels at Newmont Gold Co. was brought about primarily by the economic incentive to exploit increased reserves. From 1987 to 1989, mined production increased by 260%, gold production by 238%, and manpower by 166% (Table 1). These increases came quickly and demanded

Jan 1, 1990

By David G. Hammond

INTRODUCTION Previous papers and discussions at this conference have already covered the subjects of identification and nature of risks, allocation of risks and contractual arrangements. In this portion of the conference, in the light of topics already covered, we will consider how to minimize risks and how to mitigate losses. Webster defines mitigate as "to make less severe or painful", an apt definition for our purpose! RISK MANAGEMENT POLICY The first thing that must be said about risks, especially in construction, is that they exist and that they don&apos;t necessarily fall alike on the just and the unjust. Some risks, i.e., some kinds of risks, must be recognized as inevitable in engineering and construction and therefore must philosophically and realistically be accepted as part of situations to be dealt with. Dealing with means minimizing, covering, and sharing of risks and doesn&apos;t mean merely passing off the risks to someone else. While some risks can be avoided, for example, whether the structure will fall down or the excavation will cave in, risks management primarily deals with: A. minimizing risks---whomever risk it may be B. equitable sharing of those risks among the participants.

Jan 1, 1979

By Eugene F. Casey, William H. Hansmire, J. Ghaboussi, Randall L. Lentell, Harvey W. Parker

INTRODUCTION Construction of a major intercepting sewer in Brooklyn, New York involved tunneling in soil over several subway lines. In two instances the clearance between the subway and sewer was sufficiently close that concern was raised about the influence of the new construction. Prior to each critical crossing, analytical studies were performed which characterized the tunneling influence. It was demonstrated that with adjustments in construction procedures the crossings could be made without affecting the integrity of the subway linings. A comprehensive program of instrumentation and full-time monitoring was undertaken to ensure that any unforeseen adverse developments during crossing would be recognized. The successful crossings were subsequently made with minimal influence. Reported herein are the special construction conditions for the two crossings, the analytical simulation of behavior, and the results of monitoring on the subway linings. SEWER TUNNEL CONSTRUCTION AND EXISTING SUBWAYS The Red Hook Intercepting Sewer is a 2600 m (8600 ft) long tunnel which is part of a major water pollution control project in New York City. For clarity of nomenclature, the sewer is termed a &apos;tunnel&apos; while the rapid transit structures are termed &apos;subways&apos;. For routine construction, the tunnel was mined by hand with a 3.2 m (10 ft-5 in.)

Jan 1, 1981

By William J. Lang

In just over a generation, the United States bentonite industry has grown from almost a rake and shovel operation into one with a multimillion ton annual production rate and exports to all corners of the globe. Bentonite production, pressed to keep pace with the soaring demand, has increased more than 10 fold in the last 30 years. The worldwide demand for bentonite is expected to double during the next eight to ten years. It remains to be seen whether U.S. producers will be able to maintain the dominant position in the world market. It should be noted that accurate statistical information regarding production or market information is difficult or impossible to obtain abroad and also within the United States. Published information obtained in response to questionnaires of the Bureau of Mines tends to be on the conservative side. FOUNDRY It has only been in the last thirty or forty years that bentonite has become an indispensible part of the age old metal casting industry. The relationship has proven most beneficial to both industries and promises to be long lasting. The foundry market for bentonite was the least of the three major markets twenty years ago but now leads all others and consumes 1/3 or more of the

Jan 1, 1971

By C. J. Johnson, C. J. Bise

Abstract - As the US coal industry moves into the next century, it is becoming more apparent that the effective application of new technology is the only way it can remain competitive in the energy marketplace. Examples of this emphasis are with us today in such diverse areas as face- ventilation and excavation-equipment applications. The focus of this new technology is directed toward improvements in health and safety, cost control, and productivity. Room-and-pillar mining accounts for approximately 68% of the nation&apos;s underground coal production; this percentage is not expected to decrease markedly in the near future. As such, this paper analyzes the impacts of the changing techno- logical climate on future room-and-pillar operations by comparing a base-case section (current) to three scenarios incorporating new or emerging technology. A microcomputer-based comparative analysis will reflect the changes in section production and costs.

Jan 1, 1990

By Kimberlie Staheli

A new sanitary sewer was installed in Pleasant Hill, California using microtunnelling methods. The project consisted of 693 meters of 1372 mm and 1981 mm concrete pipe. A Herrenknecht AVN 1200 was used to install the nominal 1372 mm pipe in three drives. The machine was then fitted with an oversized shield used to install the large diameter pipeline. This articulated shield allowed the excavation of a 2362 mm diameter hole with a 1524 mm machine-- a technique new to North America. This paper reviews the design considerations for the articulated shield and reports on the project challenges and solutions to overcome these challenges.

Jan 1, 1995

By Z. Abdel-Khalek, Hassan El-Shall, S. Farrah, C. Boice

Selective adsorption and surface modification of minerals by surfactants is the primary step in the process of separating certain minerals with similar physical and chemical characteristics in the flotation process. In this study, microorgan- isms are used as surface modifiers for francolite and dolomite. Results of adsorption experiments with francolite and dolomite show that the microbes selectively adsorb to one of the minerals under specific operating conditions. In preliminary flotation experiments, it is found that the microorganisms enhance or depress flotation of the minerals leading to an increase in the efficiency of separation between the francolite and dolomite. The conditions leading to selective adsorption (surface modification) and subsequently to possible efficient separation of these two minerals are discussed in this paper.

Jan 1, 2002

By D. D. Eyer

New or improved technology will continue to drive productivity improvements through the next decade. In January 1988, I presented a paper titled, "Large Underground Mines of the 1990s? before the SME. I will follow some of the themes developed in that paper as modified by our experience in the past two years. In order for a coal company to be profitable today, it has had to reduce unit costs experienced in the past. This is because the current average realization, even accounting for a recent strengthening, remains below that of a few years ago. Doing business as was done in the past is not good enough. The coal industry needs to increase productivity in the range of 5-10% annually merely to stay even with rising costs. Underground productivity has been increasing more rapidly than that for surface mining. With the exception of the Powder River basin of Montana and Wyoming, underground productivity has caught up with that for surface mining in many regions of America. There are a number of technological factors which have attributed to increases in underground productivity and which should be factors in the future.

Jan 1, 1990