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By R. E. Nivens

In the past, Newmont Gold Company relied on cement for their ore agglomeration process. With assistance from Betz Industrial, Newmont began Investigating the use of polymers for ore agglomeration. If gold recovery would not be jeopardized, then polymers could replace cement and possibly reduce operational costs associated with cement agglomeration. The following outlines the preliminary testing conducted to determine the feasibility of polymer agglomeration with Newmont's ore and the results of the test heap, which was constructed so the program could be examined under actual operating conditions. Similar polymer agglomeration testing has been successfully performed in other Nevada gold operations. By eliminating the need for cement, a polymeric agglomeration program could improve material handling operations, as well as offer the following additional savings. First, the polymer application uses only lime for adjusting basicity, the polymer does not contribute any alkalinity to the heap. Because lime is more soluble than cement, detoxification of the heap becomes much faster and less costly for the mine relative to rinsing cement alkalinity. The following graph compares the detoxification rate of cement and polymer over a 33 day cycle.

Jan 1, 1993

By Edmund C. Bitzer

The unit costs of dry crushing, within the efficient reduction ranges of equipment now available, are considerably less than those for the reduction of the same material in the same size range by wet mills using grinding media. This is a commonly recognized fact which cannot be disputed; still we find considerable imbalance in costs between the crushing and grinding sections of many operating mills. In other words, there are many instances where more reduction could be accomplished in the lower cost area of dry crushing. In addition, equipment is now available which enlarges this area and makes it possible to consider much finer crushing than has been heretofore economically feasible. There has been a tendency for the past two decades to utilize wet rod-¬milling in the reduction step. This actually amounts to a fourth stage of crushing in a size range formerly served by roll crushers which have fallen from favor on account of high operating costs, Some investigations have indicated that there is not sufficient difference in the operating costs of rolls and rod-mills to give a clear cut advantage to either method, There has for some time been a need and an opportunity for a dry crushing process to improve costs in the range now served by these two systems.

Jan 1, 1965

By A. K. Sheik, W. G. Pariseau

A small underground mine in northern Idaho was used as an experimental facility for studying the role of water in the analysis of mine opening stability. Laboratory test data, borehole measurements and geological mapping assisted in constructing a coupled finite element model of the rock mass. The model was used to make quantitative estimates of: 1) rock stress, strain and displacement changes, and 2) water pressure and flow velocity changes that occurred during historical mining. Stope cuts and wet fills were included in the analysis. Stability of crown pillars between stopes was of particular interest. The relatively low effective stress and high rock mass strength showed that water pressure changes were of no great consequence in agreement with experience. The computational tools used in the analysis may be applied to other wet mines with appropriate changes to site-specific input data.

Jan 1, 1999

By Donald C. Rotherham

The Endako, British Columbia, deposit was initially discovered in 1927 by two local men, Charles H. Foote and Alf Lagdon, who were at that time on a hunting expedition. Four mineral claims were located to cover an area of quartz-molybdenite float that was centered on two small ridges. They subsequently uncovered a 0.5-m (1.6-ft) wide vein on which an inclined shaft was sunk to a depth of 8.3 m (27.2 ft) in 1934. Additionally, a short adit was driven to intersect another vein. Numerous trenches and small pits were also dug. Small test shipments of vein material from this early work were sent to G.S. Eldridge and Co. in Vancouver for metallurgical testing. A concentrate assaying 89.2% MoS, was produced with a recovery reported as 93.3%. The concentrate was essentially free of copper, arsenic, and phosphate. The property was examined by many geologists and engineers during 1934 to 1952, but the only work done was undertaken by the owners in order to maintain their claims in good standing. In 1952, Kennco Explorations (Canada) Ltd. carried out a limited program of bulldozer trenching, sampling, and geological mapping before relin- quishing their option. In 1956, American Standard Mines Ltd. acquired an option on the property, but no assessment work was apparently recorded and the property was allowed to lapse. The key claims were restaked in 1959 by C. Riley and H.T. James of Vancouver. The property was optioned from the new owners by Andrew Robertson in July 1961, and a small amount of trenching was conducted. Robertson, on behalf of his own company, R & P Metals Corp., reoptioned the property in January 1962. The initial results of this work were favorable and justified further exploration. The additional finances required to continue the program resulted in the formation of Endako Mines Ltd. (N.P.L.) on June 21, 1962. Field work by R & P Metals and the first Endako Mines exploration was directed by Bob Couts.

Jan 1, 1991

By George Saratsis, George Exadaktylos

In the marbel industry, ore reserves refer to the produced tonnage of orthogonal prismatic, defect-free blocks of commercial sizes and of marketable aesthetical quality. On the contrary, in the mining sector, ore reserves refer to the tonnage of ore with grade above some cut-off value. While in the mining sector ore reserves are reported according to existing standard guidelines, the marble industry has no standardmethod. The purpose of this paper is to present a method to estimate white marble reserves using drill coring or borehole wall logging and limited joint mapping on exposed marble surfaces. Data pertaining to fracture orientation, fracture frequency, size, and whiteness were collected. The primary phase of marble characterization is followed by the discretization of the orebody into a three-dimensional array of orthogonal prismatic blocks, where the marble whiteness and fracture intensity are attribute values. Both these variables are considered to obey continuous and not discrete probability distributions. The discretization is performed using computer aided design and the Block Kriging techniques. An outline to improve the description of a given marble ore deposit at the exploration stage is presented for the prediction of marble block size distribution from joint count measurements along diamond drill cores. An example case of a white dolomitic marble quarry is used to demonstrate these methods.

May 27, 2020

By J. Stowe

"While there has been continual improvement in the models for predicting deposition velocity and pipeline friction losses, the fundamental design philosophy for tailings pipelines has remained the same over the previous three or four decades: design the tailings pipeline to operate in turbulent flow without a deposit on the pipe invert for all expected process conditions. Recent improvements in the understanding of slurry pipeline flows allows for the design of pipelines operating with a deposit on the pipe invert, allowing the system to operate at moderate velocities for high flow rates, optimizing system energy requirements and maximizing pipeline wear life.Tailings pipelines are increasingly operated at higher solids concentrations when there is a greater likelihood the pipeline will operate in laminar flow due to the higher tailings slurry rheology. Historically, slurry pipelines have been operated in turbulent flow. We now know that laminar-flow pipeline operation is possible as there are several operational laminar-flow tailings pipelines. While our understanding of laminar-flow slurry pipelines is not complete, recent research provides guidance on how to approach the design of these pipelines.New sensor technology has led to the development of an instrument that provides reliable indication of bed-deposit height within a pipeline. This technology is particularly helpful in operating pipelines with a deposit and has application in better understanding the operation of laminar-flow pipelines. Failure of tailings pipelines can result in consequent damage to surrounding structures and unacceptable spillage into the environment. Modern pipeline leak detection technology allows operators to better manage this risk by ensuring safe and reliable operation of tailings pipelines.This article provides an overview of the each of the above advances in the design and operation of tailings pipelines.Operating tailings pipelines with a depositTailings pipelines, and slurry pipelines in general, are typically designed to operate without a deposit on the pipeline invert. Meaning, the minimum operating velocity exceeds the turbulent deposition velocity. This approach has been adopted due to concerns regarding potential blockage of a pipeline operating with a deposit."

Jun 1, 2019

By J. F. T. Agapito, L. J. Gilbride, K. Hollberg

Room-and-pillar mining at the Big Island Mine uses narrow, yield (i.e., load transferring) pillars to achieve high resource recovery and productivity. Two flat-lying 3- to 3fi-meter (10- to 11fi-ft) seams are mined. The interburden between the seams is about 10 meters (33 ft) and the cover depth is 250 to 330 meters (820 to 1,080 ft).Most of the mining has been single-seam, but two-seam mining will begin in the near future. Yield pillars minimize stress transfer between the seams. However, it is important that good long-term stability be maintained to prevent subsidence over a large portion of the mine beneath the Green River channel. Three stress issues impacting stability are discussed in this paper: (1) higher-than-gravity vertical pre-mining stresses, (2) time-dependent stress transfer or arching, and (3) stresses induced by strata gas. Although the stress environment and behavior is not fully understood, steps have been taken in mine design and operations to minimize impacts to stability. Stress determinations have been very important to verify analytical predictions used in mine design and in long-term stability assessment.

Jan 1, 2004

By R. M. Damodaran

The flotation performance of Florida phosphate rock was evaluated in terms of the mixing behavior of reagents with particulates during anionic conditioning of phosphate slurries. The various conditioning variables that influence mixing, namely, solids loading, agitation speed and the conditioning time were investigated to determine their effect on reagent coating on the particles. The phosphate recovery was used to monitor the conditioning efficiency. The mixing characteristics of the phosphate feed were evaluated in terms of the ratio of the mixing power P, to the minimum power Pm' required to keep the slurry in suspension. It was found that mixing conditions govern the conditioning time required to obtain high recovery. Reagentization was slower at lower P /P m ratios. At higher P /P m ratios, the flotation recovery was optimized and the agitation speed was found to have no significant effect on it. Optimum mixing conditions were obtained for a 74 wt% slurry at an agitation speed of 450 (47 rad/s) rpm. Under the optimum conditions of mixing, recovery was improved at low collector dosages and short conditioning times.

Jan 1, 1995

By Günter Strappler, Max John

When tunneling through karstic terrain, diverse and complex karst structures are to be expected. By means of drilling ahead of the face using drill jumbos, these structures can be detected to such a degree that by applying proper support measures both open karst cavities and karst holes surrounded by boulders embedded in soft rock can be mastered without causing any break-outs. Support measures such as spiles ahead of excavation, sealing off cavities, back?lling with sand, etc. have to be planned schematically and adapted to the dimensions and formations of the karst structures on site. An essential requirement for a smooth excavation procedure is the availablility of all necessary tunneling equipment for excavation by drill and blast as well as for excavation of soil, with experienced tunnel engineers being in charge of any adaptions on site.

Jan 1, 2003

By M. J. Allan, D. J. Barratt

This paper reviews current testing methods for sizing autogenom and semiautogenom mills in the North American context with comments on the necessity for test work and requirements for different circuits and equipment selection. The economics of testing and the value received are discussed.

Jan 1, 1987

By C. Roos, K. Jetmore

Developing a strategic underground mine plan is challenging and investigating multiple scenarios may take weeks. This process can be sped up using the Theory of Constraints to isolate the bottleneck mining activity and simplify the mine schedule process. This paper presents a technique to apply the Theory of Constraints to test multiple cutoff grade scenarios in Mineable Shape Optimiser and quickly produce many high-level production-based schedules that can be easily interpreted using stope-by-stope graphs, the Hill of Value, and through incremental return analysis.

Mar 2, 2022

By Paul E. Scheerer

Synthetically produced magnesium hydroxide serves as the precursor for much of the magnesium oxide produced in the world today. Magnesium oxide, in a variety of physical and chemically reactive forms, is a very important commodity. It is used as the main component in refractories employed in steelmaking furnaces and in many base metal refining furnaces. In the chemical industry, it serves as a raw material in the production of epsom salts, rayon acetate, oxychloride and oxysulfate cements and magnesium sulfonates. It is a minor component in fertilizers and animal feeds. It serves as the starting material for producing fused magnesia, used as an electrical insulator in electric heating elements. It is employed in the magnesium sulfite process for pulp digestion in the paper industry. Additional uses are in SO2 scrubbers, as a neutralizing agent in the tanning industry and as a component in rubber compounding. Magnesium oxide is produced not only from synthetically produced magnesium hydroxide. It is produced from natural magnesites, natural brucites, and natural and synthetic hydro-magnesites. Synthetic magnesium hydroxide, as a starting material provides more control of the chemical purity and chemical reactivity of resulting magnesium oxide products because of the uniform nature, chemical and physical, of the hydroxide that can be produced. Synthetic magnesium hydroxide is produced by precipitation of Mg (OH)2 from magnesium chloride bearing seawater or natural brines through the use of a base such as Ca(OH)2 or NaOH.

Jan 1, 1978

By R. A. Matuszak

Historically most mine management teams have been forced to operate in a more or less subjective manner. The objectives of mine management are simple and clear. Like other operational managements, mine management teams have the traditional well defined goals of improving efficiency and production while decreasing costs. Unlike other operational managements however, mining teams deal regularly with a vast assortment of uncertainties caused by: - Key production tools being mobile and widely dispersed, and - Non-uniform mining conditions At best in most operations these conditions cause obstacles to productivity and at the same time cause long delay in managment awareness of the obstacles. Planning with delayed feedback of information about necessary deviations is incomplete planning. For these reasons increased operational efficiency remains a constant though somewhat elusive goal.

Jan 1, 1985

By Paul Madsen, Bade Sozer, Thomas Hennings, Eileen Test

The Rondout Bypass Tunnel in New York has two access shafts. The upper sections of the shafts are lined with steel pipe to resist a substantial net internal water head . Initial design included a ¾-inch-thick cement mortar lining (CML) for all three components. Because of concerns with CML application on large-diameter pipes, the protective lining was redesigned for shotcrete application. This paper discusses the details of that design, mock-ups, and shotcrete application.

Jun 13, 2023

By Kyle Amoroso, Larry Applegate, Aaron K. McCain

The use of frozen soil as ground improvement and temporary ground support for the excavation and construction of cross passages and adits has gained in popularity over the last decade. Frozen soil provides a number of advantages for this application such as being waterproof, structurally stable, and working well with any soil type. One of the greatest advantages is the ability for the system to be adaptable to the project geometry and site limitations. Multiple case histories illustrate that freezing can occur from the ground surface, from within the tunnel, or as a combination.

Jun 13, 2023

By R. D. Lord

This paper deals with the search for the best practical means of storing sulphide bearing tailings, where there is no residual excess of carbonate material. It is the common experience that the sulphide content decomposes, with the aid of bacterial action, and the resulting sulphuric acid escapes, along with any heavy metal solutes, through embankments that are usually porous to some degree. The problem is typified in the tailings of the uranium operations of Elliot Lake, Ontario, where mining started some 20 years ago. The approach to tailings disposal paralleled the practice for other hydrometallurgical plants treating gold and base metal ores. Impoundment areas were designed to retain solids, and a clear and neutral overflow was considered satisfactory practice. Now experience has shown that these areas, some idle for over a dozen years, release acids, in seepage and overflows, to an unacceptable degree. To protect natural water courses neutralizing plants are operated wherever required. Lime slurry is fed continuously into the tailings outflows in a quantity sufficient to raise the pH to 8.5 and precipitate heavy metals that may be in solution. The objection to this procedure is that the plants will require servicing indefinitely, unless a better remedy is found.

Jan 1, 1975

By B. Waterman, R. Collins, V. R. K. Paruchuri, P. Gonzalez, H. Dijkman

"INTRODUCTION Mining and processing of sulfide ore bodies has the potential to solubilize sulfate. Gypsum in the host rock, as well as oxidation of sulfides during milling and processing can solubilize sulfate. Acid rock drainage (ARD) also has the potential to generate waters high in sulfate. Even after treatment of the ARD with lime, the treated water can have sulfate present in gypsum saturation levels. Most mine-sites reuse sulfate impacted water but as a mine nears closure, reuse options may be limited and water treatment becomes an option. Furthermore, sulfate discharge requirements, particularly for anti-degredation narrative standards, can be very strict. Freeport has investigated many new technologies to economically remove sulfate from these types of water. A Dutch company, Paques B.V. developed one of these technologies and it utilized biological reactors to convert sulfate into elemental sulfur in a 2-step process. In 1992 the first industrial reference of the SULFATEQTM technology was commissioned at the Nystar Budel zinc refinery in the Netherlands. PILOT PLANT TECHNOLOGY AND DESCRIPTION As shown in Figure 1, the plant contains several process steps, which can mainly be divided into the following sections: 1. Anaerobic biological system in which sulfate is reduced to hydrogen sulfide by sulfate reducing bacteria. 2. Aerobic biological system in which hydrogen sulfide is oxidized to elemental sulfur by sulfide oxidizing bacteria. 3. Solid/liquid separation in which sulfur, calcium carbonate and biomass solids are separated and dewatered. Sulfate impacted ground water is pumped to the feed water tank through a plate and frame heat exchanger to maintain the solution temperature around 95°F. A custom mix of micronutrients is dosed to the feed tank. This nutrient mixture provides essential elements for the growth of anaerobic and aerobic biomass. Urea is added to the feed tank and provides the required nitrogen source to the biomasses. The pretreated feed water is pumped into the anaerobic reactor. The reactor works on the gas lift principle. Sulfate reducing bacteria utilize hydrogen gas as electron donors and reduce sulfate to hydrogen sulfide. This reaction increases the alkalinity of the solution. Carbon dioxide gas is added in order to control the pH within working range of the reactor. Due to the low solubility of the hydrogen gas, the anaerobic gas mixture is recycled through the system. The gas mixture recycle also provides the gas lift for mixing within the anaerobic reactor."

Jan 1, 2016

By E. Lefeuvre

Precambien in age, the phospate deposit under study which outcrops to the south forms a synclinal consisting of only one mineralized horizon. The synclinal strikes SSW/NNE, dips from 30 to 60 NNE and is about 5 km wide. The deposit has been explored by : - trenches and pits about 50 m apart in the outcropping area ; - core drill holes forming lines perpendicular to the outcrop. These lines are about 100 m apart. On each line, the drill holes are about 50 m apart The phosphate layer is clearly visible and has then been defined from the geologicia1 description of drill hole logs. The layer has been divided into two parts : a very rich, altered part at the hanging wall and a poor part displaying opposite physical characteristics, i.e. a fresh and hard rock. With open pit mining in view, the deposit has been divided into a 3-dimension network of blocks, each block measuring 50 X 50 X 100 m. The tonnages of rich and poor ore, PO25, MgO, Si02, CaO and R2O3 grades and the tonnages of barren waste at the hanging wall and the footwall have been calculated for each block. Given the dip of the phosphate layer ranging from 30 to 60° and its relative thickness (between 10 and 15 m), it was impossible or inappropriate to carry out direct calculation by 3-dimension kriging : too many neighboring blocks to obtain sufficient date and impossibility to draw up the morphology of the layer.

Jan 1, 1986

By F. M. Doyle, Jun Li, Milton E. Wadsworth, Ximeng Zhu, E. Peters

The electrochemical behavior of pyrite in borate/sulfate solutions was investigated using cyclic voltammetry. Three anodic peaks at approximately -0.8 V, -0.1 V and +0.5 V (SCE) were detected along with their corresponding reduction peaks. The first two peaks correspond to the oxidation of surface products. The third peak corresponds to the direct oxidation of pyrite with reaction products FeO oxides. sulfate ion and partially oxidized sulfur intermediates present as a surface film of polysulfides and So. The Few oxides and sulfur intermediates were reduced to ferrous hydroxide and HS during the negative-going scan. The HS interacted preferentially with Fe(OH), on the surface to form FeS. Excess fenous hydroxide continued to reduce to metallic iron. During the return positive-going scan, metallic iron was oxidized to ferrous hydroxide and FeS was oxidized to pyrite. These reactions are characterized by a unique double peak observed in the region -0.8 to -0.65 V. The growth kinetics of the surface sulfur film formed during anodic oxidation were studied using chronoarnperomeay. Potentiostatic measurements were well correlated by a paralinear rate equation, suggesting the formation of an intermediate passive film, associated with the simultaneous dissolution of the outer layer of the film. The reaction rates were affected by applied potential, solution pH and temperature, but were independent of electrode rotation speed. A reaction kinetics model which fitted well with experimental results, was developed.

Jan 1, 1993

By M. Katzer

The effect of selective dispersants as wet grinding aids for ores is demonstrated on laboratory scale batch and continuous grinding equipment. A complete characterization of behavior is performed on a given ore to demonstrate correlations involving torque, % solids, net production rate, and slurry weight and volume loading. The relationship between such laboratory data and industrial scale testing results is very consistent.

Jan 1, 1979