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By J. R. Larsen

The perlite review arrived too late to appear in the June issue. Worldwide production of perlite in 1991 was estimated to be 1.7 Mt (1.9 million st). Events in Eastern Europe and the former Soviet Union caused reporting of production, consumption and reserves from those regions to cease. The US Bureau of Mines reported data only from the US and Greece. Together, the two countries produced about 701 kt (773,000 st), down from 739 kt (815,000 st) in 1990. US production of perlite amounted to about 547 kt (603,000 st) last year. US production was supplied by 10 companies operating 11 mines in seven western states. There are 74 plants producing expanded perlite in 33 states and in Canada. All the companies engaged in mining perlite are also expanding it.

Jan 1, 1992

By G. R. Wheeler

Epithermal gold exploration in the last decade has developed useful models for exploring previously overlooked ore districts in Oregon. In eastern Oregon, disseminated gold occurs in epithermal deposits that have been pervasively silicified and brecciated. Many gold prospects staked since 1980 are in fluvial and lacustrine sandstone and conglomerate deposits. Clay alteration products and disseminated pyrite may be present. Vein filling calcite and thin to thick quartz veins are common. Late stage quartz forms pseudomorphs after calcite in many prospects. Arsenic, mercury, and gold are geochemically anomalous but silver is usually not. The epithermal deposits are located in part of the Deer Butte formation or equivalent units. Exploration criteria include the presence -of Deer Butte formation or equivalent units and northwest structures cut by north-south basin and range structures.

Jan 1, 1987

By John A. Herbst

At the last Comminution Symposium a challenge (Meloy and Williams, 1992) was issued to "predict the typical straight-line, self similar" tumbling mill product size distributions using a population balance model (PBM). Implicit in this challenge is the assumption that the PBM is inadequate for predicting real world grinding performance. This response is presented in three parts: I. Theoretical analysis of the general PBM and its appropriateness for comminution system modeling. II. Examination of the accuracy of prediction of real world milling behavior using linear and nonlinear PBMs. III. Evidence from recent microscale comminution research. This paper concludes with recommendations concerning future research which will: 1. further elucidate mechanisms of particle destruction and creation as well as attrition and 2. increase the accuracy of model predictions in highly nonlinear situations

Jan 1, 1997

By M. Ruonala

The Larox Power PF Pressure Filter has been developed to meet the challenges of ever increasing output tonnages demanded by the minerals processing industry. This paper will highlight recent experiences at the Rudna Copper Concentrator in Poland, the Escondida Copper Concentrator in Chile and some large zinc concentrators in Australia. Detailed maintenance and operating cost information will be disclosed. Emphasis will be placed on economics on scale gained from higher machine throughputs.

Jan 1, 1998

By A. E. Ketler

Optical smoke monitoring fills an important gap in ventilation and fire safety: namely monitoring of smoky, low temperature fires where little CO and heat are generated. Smoke monitoring also avoids the nuisance alarms due to diesel exhaust, battery chargers, blasting and welding. The smoke optical density (OD) fire alarm standard specified by MSHA presents an opportunity for improved safety. Experience of actual mine usage of the SmokeBoss*100 is reviewed, with particular regard to effectivity, maintenance and cost.

Jan 1, 1995

By Gilman Y. Murray

The problems connected with the development of economically acceptable water supplies in arid regions are discussed. The techniques for capture and retention of runoff from infrequent desert storms are described and the major factors involved are emphasized. The exploration and planning for a typical water development in southwest United States is described, including an analysis of capital and operating costs for the proposed system.

Jan 1, 1963

By J. J. Wallaert

The decreasing supplies of natural gas and low-sulfur crude oil available for electric power generation in the United States will unquestionably shift the emphasis to nuclear and coal fired steam power plants in the immediate future. Failure to do so will ensure our dependence on mid-east low sulfur crude oil comprising some 70% of the known world reserves, and imported liquid natural gas. By contrast, the United States has 43% of the known world reserves of anthracite, bituminous and semi-bituminous coal and 48% of all known coal reserves of the world including lignite. It is evident, therefore, that coal is alive and well and will continue to be a significant energy source for the production of electricity for many years. Of course, concern for our environment and the development of new technologies will ultimately curtail the utilization of coal for the generation of bulk power, but information released by the National Electric Reliability Council and the Federal Power Commission is worth repeating. In the year 1972 the total capacity of generating units in the United States was 379,552 Mw of which 149,974 Mw, or 39.5% of the total, was produced by coal fired steam turbines which consumed 344,700,000 tons of coal. New capacity additions planned or in construction show that in the year 1981 our total generating capacity will be 843,503 Mw, of which 257,995 Mw, or 30.6% of the total, if from coal only. Translating this increase into terms meaningful to the bulk material handling industry suggests that ten years from now the utility industry will require 590,000,000 tons of coal per year - a monumental task - if we are to sustain our current demand rate for power.

Jan 1, 1973

By Roy H. Werner

The environmental demands on the mining industry coupled with rising production costs have created a need for a low cost sludge removal system. The HYDRA* system meets these demands by offering a unique means of removing settled solids from the bottom of a clarifier or a thickener. This underflow system combines experience and proven concepts to form a low cost sludge removal system. The HYDRA system incorporates a flexible design that can be adapted to any settling area. The components are readily available and cost less than a conventional clarifier or thickener. Existing technology developed by preparation engineers provides for retrieval and recovery of mine preparation plant refuse. However, past retrieval methods have been extremely costly. The HYDRA system, because of its low cost, makes the complete process of retrieval and recovery economically feasible. This allows wasted resources to be converted to a saleable product.

Jan 1, 1975

By K. H. McDaniel

An interactive mine ventilation simulation software program (WIPPVENT) was developed at the Waste Isolation Pilot Plant (WIPP). The WIPP is a U.S. Department of Energy (DOE) research and development project located near Carlsbad, New Mexico. The facility is designed to provide a permanent, safe underground disposal of U.S. defense generated transuranic waste in bedded salt. In addition to its regular functions, the underground ventilation system is engineered to prevent the uncontrolled spread of radioactive materials in the unlikely event of a release. To enhance the operability system, Westinghouse Electric Corporation has developed an interactive mine ventilation simulation software program (WIPPVENT). While WIPPVENT includes most of the functions of the commercially available simulation program VNETPC (copyright © 1991 Mine Ventilation Services, Inc.), the user interface has been completely rewritten as a Windows ® application and screen graphics have been added. WIPPVENT is designed to interact with the WIPP ventilation monitoring systems through the site wide Central Monitoring System.

Jan 1, 1996

By R. G. Swanton

The Bureau of Mines is investigating the leaching of phosphate values from Florida phosphatic clay wastes using sulfuric acid (H2SO4) as the leaching agent and methanol as the solvent. Acid-alcohol leaching studies were done using pure crystalline apatite to investigate potential causes for low extractions. It was found that a barrier layer formed on the surface of the apatite. Initial discovery of the barrier layer was made by analyzing pure apatite samples before and after leaching using an optical microscope. Subsequent Fourier Transform Infrared (FT-IR) analyses proved the coating was calcium sulfate hemihydrate (CaSO4-1/2H2O) and that unreacted apatite existed beneath the coating. Scanning electron microscope (SEM) photographs depict the CaSO4-1/2H2O morphology as long slender crystals adhering to the apatite surface. It was also shown that grinding the leached tailings and leaching again in the H2SO4-methanol system resulted in additional phosphate extraction.

Jan 1, 1991

By T. Glenn Pobanz

For more than fifty years Walter Kidde & Company, Inc. has engaged in the development and manufacturing of both fire suppression and detection equipment. Our initial work for the mining industry centered around dry chemical extinguish-ing equipment for mine haulage cars. To fulfill this need, Kidde engineered and developed a manually activated dry chemical system to provide protection for the wheel wells, cable reels, and motor compartments on various pieces of underground mining equipment. The next phase of mining operation fire protection for Kidde was the area of detection and automatic fire suppression for conveyor belt heads. Early in 1970, a field evaluation program and belt head demonstration unit was taken to 10 areas throughout West Virginia, Kentucky, Pennsylvania, and Ohio. This extensive field program was a joint effort with National Mine Service Company of Pittsburgh, Pennsylvania. The objectives of this program were to study mine hazard problems and to determine further requirements of mine operators. The resulting belt head detection system centered around our Continuous Strip Thermistor Core heat detector in conjunction with a Kidde stored pressure dry chemical extinguishing system. Continuous Strip detection has been in use for a number of years in aerospace applications. It has proven flexible and reliable for the rapid detection of overheat conditions and fires in engines of over half the aircraft flying today. The use of Continuous Strip gave us flexibility to protect surface areas over and around the actual conveyor belt head equipment. The nature of Continuous Strip allows us to bend, wrap, and attach the 20 foot long thermistor element over the desired protected points of the belt head. An integral part of the conveyor belt head protection system is the control panel utilizing our comprehensive knowledge of fire alarm control logic. This panel contains supervision circuits which sound trouble signals upon detecting a break in the Continuous Strip; breaks in the wiring to the remote electrical extinguishing activators or to the alarm bell; or loss of primary power. A separate control module provides the adjustable alarm temperature setting of the

Jan 1, 1971

By C. A. Hollingsworth

The Deep Leg Flotation Cell was developed to solve a problem which confronted the Smith-Douglass Company on moving from one mining area to another. Poor recovery and, to some extent, inferior concentrate grade were encountered in the silica flota¬tion circuit. This was believed due to the softness of the phosphate which caused it to form slime. In view of the urgency of the matter, the problem was attacked from two angles. The first involved the development of a flotation cell which would not create slime and the second, a new or improved reagent for floating silica from phosphate rock which would be less sensitive to slime than reagents currently in use.

Jan 1, 1964

By W. P. Staunton, K. Jones

INTRODUCTION The increased activity in the Aus­tralian gold industry over the last decade has resulted in a concomitant increase in the use of sodium cyanide, with a projected consumption of 80,000 tonnes in 1991. Growing environmental awareness by government, industry and the public has generated increased interest in the fate of cyanide near gold mine tailings dams and has highlighted the lack of basic knowledge in the area, particularly for Australian conditions. In 1989 the Chemistry Centre (W.A,) commenced a' project, under the auspices of the Australian Mineral Industries Research Association entitled "Fate of cyanide in the Enviroment Near Mine Tailings" to investigate some of the issues arising from the management of tailings containing cyanide, The project, which has been supported by thirteen companies has three broad aims:

Jan 1, 1991

By William J. Kohan

Milling has traditionally been considered more art than science. In the last 10 years, significant improvements in process equipment have been made and we are finally taking significant steps toward approaching grinding as a science. Two machines have been at the center of this development. These are the roll press and the high efficiency separator. The former can be considered as a new technology or adaptation of existing i.e. roller mill. The latter is clearly an improvement of existing technology. Other machines have been introduced to a lesser degree and later. Among these are the CKP and Horomill. The purpose of this paper is to provide an over- view of the currently available modifications for operating systems and options for new milling circuits with some comments on their application and history.

Jan 1, 1997

By V. B. Achanti

Laboratory studies were carried out at West Virginia University to investigate the rock fragmentation mechanism by continuous miners using an automated rotary cutting simulator. The primary factors influencing the: fragmentation process were found to be: bit spacing, bit geometry, depth of cut, and cutting drum rotational speed. This paper presents the influence of these parameters in achieving optimum energy consumption and minimizing dust generation during rock fragmentation process. Three bits were used simultaneously on Indiana limestone while the bit tip angle was varied from 60° to 90°. Bit spacing was varied from 2.54 cm (1 in.) to 5.08 cm (2 in.) while the cutting process was assessed for varying cutting depths. Respirable dust generated during the course of the experiments was analyzed utilizing cascade impactors. Assessment of these parameters has led to a better understanding of the cutting mechanism by continuous miners in terms of energy consumption and dust generation.

Jan 1, 1997

By Takuya Tani, Tomoyuki Aoki, Kazuo Saskai

"The authors have proposed a unique methodology in the evaluation of rock mass stiffness for the range of five to twenty meters ahead of the tunnel face, with the use of small diameter inclinometers. The inclinometers are installed at the tunnel crown at a pre-determined constant interval, about one meter behind the face in order to obtain the slight change in inclination angles during tunnel excavation. This method was developed as a daily control measurement such that the geological condition and its possible change ahead of the face could be detected early by monitoring the trend of inclination angles. This paper describes the results of the ground stiffness ahead of the tunnel face evaluated at a mountain tunnel construction site. This stiffness is evaluated automatically and displayed visually by the current system equipped with a result display screen, together with a warning message against a weak zone when detected. 1. INTRODUCTION In a conventional planning of a mountain tunnel, according to the Japanese Standard (JSCE, 2006) seismic refraction surveys from the ground surface are performed and tunnel support patterns are then designed based on the seismic wave velocity. The resolution of the velocity profile estimated by this technique, however, is poor as the tunnel overburden becomes large. The tunnel face is therefore often encountered by unforeseeable fault zones or weak rocks. Such an unpredictable weak zone occasionally causes the collapse of the tunnel face. Clarifying the forward geological information during excavation is hence significant for safe and well-controlled construction. According to the geological conditions ahead of a face, auxiliary methods typified by forepiling and face bolting could be preliminarily prepared for prompt execution. For the purpose of acquiring forward geological information, pilot borehole drilling and seismic reflection methods represented by the TSP (Tunnel Seismic Prediction) or HSP (Horizontal Seismic Profiling) are often applied. Those exploration are carried out near the tunnel face for a couple of days. This often leads to the interruption of excavation procedure and has no small effect on the construction schedule. On the other hand, some forward ground prediction methods in the daily control measurement have been developed e.g. by Schubert et al. (1995). In this method, tunnel displacements in the direction of the tunnel axis are used together with the crown settlements. We have tested their method at a few of our tunnel projects and found difficulty in the evaluation of the forward ground condition due to insufficient resolution of the axial displacement measured by a total station theodolite that we usually use for the tunnel measurement. We have therefore developed a novel methodology of monitoring slight inclination at the tunnel crown near the face, so that the forward ground conditions can be predicted and evaluated as part of a routine measurement procedure."

Jan 1, 2016

By B. Nyman

A lot of work is in progress to improve copper recovery by leaching-solvent extraction-electrowinning (L-SX-EW). At Outokumpu the focus of attention is on SX equipment development as a result of which a new mixing-settling technology, the Vertical Smooth Flow (VSF) has been introduced. Using helical stirrers in the VSF mixers a more gentle and uniform contacting can be obtained than in the mixing compartments of the low-profile design. The benefits of Outokumpu's new approach are an essential decrease in organic losses and in aqueous in organic entrainments. Separate pumping using a smoothly pre-contacting "Dispersion Overflow Pump" (DOP) is a key feature of the VSF design. The scale-up of this pump as well as the VSF mixers are shown to follow simple mathematical relationships which also have been confirmed by full scale experiments.

Jan 1, 1995

By D. H. Lynch

This paper is a general description of current Central Florida phosphate mining, beneficiation and product transportation. It is directed and believed to be of interest to engineers not familiar with this industry.

Jan 1, 1978

By R. D. Bartlett

Large open pit mines in desert climates, such as the Phelps Dodge Morenci copper mine in Arizona, can create groundwater cones-of-depression of considerable size and :ability. The hydraulic containment provided by the groundwater depression prevents migration of process solutions into the surrounding regional aquifer. Copper leach operations that fall within the groundwater depression may not require costly lining if passive containment can be demonstrated. An approach is presented in this paper that was successfully used to demonstrate passive containment. The approach includes a combination of groundwater modeling and a water balance analysis of leaching operations failing within or immediately near the open pit.

Jan 1, 1999

By C. T. Thompson

"Rotary percussion" implies two types of energy, rotary and percussion. Into these categories fall rock' drills of varying sizes. The larger ones drill above 6" diameter holes; the medium size, 2 3/4" to 4 1/2" holes; and the smallest, 1 1/4" to 2" holes. Essentially, the larger holes are drilled with doom-the-hole drills using tri-cone bits. Percussion energy evolves from the drill piston and rotation power from the rotary table or overhead drive, using drill collars or pull down mechanism to preload the bit.

Jan 1, 1963