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By G. H. K. Schenck, H. W. Robinson

Private weather forecasting services available on a contract basis can significantly reduce the uncertainty associated with weather-induced changes in mineral production and demand. Such services offer the mineral producer the opportunity for tactical and strategic response to weather conditions. There are at least 50 private meteorological consulting services as well as numerous individual meteorology consultants. Fees for services range from $150-$600 per day for one man to over $20,000 per month where a complex forecasting or modification program is undertaken.

Jan 1, 1971

By D M. Hunter, S M. Iveson, K P. Galvin

For low density materials such as coal, density-based fractionation of particles via the sink-float method is relatively simple due to the availability of liquids of suitable density; however, for high density minerals, suitable heavy liquids are less available and those that are available are expensive and pose significant hazards. At best, sink-float separation can be performed up to densities of 4400 kg/m3 with the use of Clerici’s solution at elevated temperatures. Hence the direct measurement of grade-recovery and density-partition curves is problematic. Therefore, in most cases, beneficiation plants must rely on methods such as QEMSCAN, density tracer particles or very limited information to guide them in the design and optimisation of their plants.This paper describes a density-fractionation method utilising laminar flow through a system of parallel inclined channels to generate a series of overflow fractions at different flow velocities. Here the particles are subject to precise hydrodynamic forces with minimal dispersion or mixing. The size distribution of each overflow fraction at a given flow velocity is obtained using a laser particle size analyser, and combined with a laminar flow model to deduce the corresponding density distribution. The paper describes the application of the method to measure the separation achieved using a REFLUX Classifier to obtain the corresponding feed, product and reject ‘washability curves’, and in turn the full partition surface. Approaches used to corroborate the findings are discussed.CITATION:Hunter, D M, Iveson, S M and Galvin, K P, 2017. A batch elutriation technique for the density-based fractionation of iron ore, in Proceedings Iron Ore 2017, pp 195–104 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By William C. McBee

Sulfur concretes have been developed by the Bureau of Mines as construction materials with physical and mechanical properties that suit them for use in acid and salt corrosive environments where conventional concretes fail. Mixture design methods were established for preparing sulfur concretes using different types of aggregates and recently developed mixed-modified sulfur cements Bench-scale testing of the sulfur concretes has shown their potential value. Corrosion resistance, strength, and durability of sulfur concrete are superior to those of conventional materials. Field in situ evaluation tests of the sulfur concretes as replacement for conventional concrete materials are in progress in corrosive areas of 24 commercial chemical, fertilizer, and metallurgical plants.

Jan 1, 1983

By Frank E. Scott

During the past year interest in the use of hydrazine and hydrazine hydrate as a fuel has increased in the United States; For this reason it was felt to be desirable to obtain information on the explosives properties (if these materials in order that hazards inherent in their manufacture, storage, transportation, and use might be evaluated.

Jan 1, 1949

By A. K. Croteau

"At Craigmont Mines Limited, Merritt, B.C., the mining practice of trackless sub-level caving was started in the latter part of 1966. This type of mining was new to the mine personnel and the mining industry of Canada as a whole. Sub-level caving has presented many old and a number of new problems in maintaining the equipment used in this method. This paper will deal with some of these problems as they affect this particular mining operation. It will be impossible to review all phases of the equipment, but an attempt will be made to cover the most pertinent aspects in maintaining the drilling, mucking and hauling, and auxiliary equipment."

Jan 1, 1970

By Oliver Bowles

Granites are classed as igneous rocks ; they have been formed by the solidification of rock magmas or solutions from deep within the earth . It is an almost invariable law of nature that magmas which cool quickly form fine- grained or glassy rocks , while those that cool slowly are completely crystallized and are coarser- grained . Granites , being of the latter class , are regarded as having attained their solid form at considerable depth below the surface under conditions of high temperature and pressure . The constituent minerals crystallized out slowly , the crystals interlocking with one another . The great depth of overlying rocks that must have been present when crystallization took place has been removed by erosion over large areas on the surface of the earth , in consequence of which granites appear at or near the surface in many localities . The chief minerals of which granites are formed are feldspars , quartz , and either mica or hornblende . All the essential constituents except mica are as hard as , or harder than steel , therefore granites are difficult rocks to cut and dress . Granites are usually red , pink , or gray , depending on the color of the feldspars . If hornblende or black mica is abundant the rock may be dark green or almost black . Granites are characterized by massive homogeneous texture . They are classified as fine- grained , medium- grained , or coarse - grained . Medium- grained granites are those in which the feldspar crystals average about one- fourth inch in diameter . If relatively coarsegrained crystals appear in a fine -grained ground mass the rock is designated a porphyritic granite . Uniformity in texture and grain size are desirable in building and ornamental stone , although occasionally rocks of variable texture , such as the porphyritic granites , are used . A rock may have the mineral constituents of a granite but show a banded or platy structure due to recrystallization , folding , or other changes while the rock was in a plastic or semimolten condition . Such metamorphic rocks are called granite gneisses . They are used occasionally for building purposes but not as commonly as the uniformly textured granites . - Granites are named from the most abundant mineral other than quartz and feldspar that they contain , being called , for example , biotite granite or hornblende granite . - Commercially other igneous rocks granitoid in texture but more properly classified as syenites , diorites , or gabbros may be classed as granites . Thus the " black granite " of Little Falls , Minn . , is a diorite , and the " black granite " of Eastern Pennsylvania consists of diabase or gabbro . The question is sometimes raised as to the depth to which a granite occurrence may extend . In this respect granites differ notably from limestones , sandstones , or other sedimentary rocks . The sediments were originally laid down in relatively thin beds , and individual formations providing rock of economic value may be quite limited in thickness . Usually the usable beds range between 40 and 200 feet in thickness . On the other hand , granite comes up from below . Its depth is unknown , but in general is very great . It may even be measurable in miles . The reserves of material at depth are to be measured , therefore , by the economic depth of working rather than by the vertical extent of the rock mass . Exceptionally , granites of commercial quality may occur in sills or sheets of limited thickness flanked on either side by rocks of different character , as , for example , at Westerly , R. I.

May 1, 1930

By AJ Rorke, JD Botes

Presplit blasting in strip mines is aimed at creating a safer wall to work under during the coaling operations. Good quality presplits are also necessary for effective throw blasting and drainage of the blast block. A less obvious but important function is full coal recovery. Optimum Colliery has been experiencing rock freezing against the presplit highwalls. The rock formed in patches along the highwall and trapped coal beneath it. The material that was &ozen comprised the rock between the back row of holes and the presplit and was often up to 3 m thick (the stand off distance between the back line and the presplit). The cozen rock formed predominantly along the bottom halfor bottom two thirds of the highwall. Along the top portion of the highwall, the presplit crack was usually well formed with visible barrels. This problem, or similar variations of it, is common on many South African strip-mine operations. Investigative work was carried out at Optimum Colliery to correct the problem. This paper presents the information and measurements that were made and discusses the solutions that have been applied to solve the problem. It was found that there were two independent causes for the tiozen material, with each contributing more or less to the frozen rock along the highwall. It was found that the presplit was not forming properly in places, especially closer to the bottom of the highwalls. The reasons and the solutions are presented. The second cause was found to be associated with reduced detonation velocity in the back line holes coupled with low confinement from long delay periods. Emulsion explosive that is sensitised with air bubbles was found to be prone to this phenomenon near the back of high-energy blasts. A change in the explosive formulation in the back-line holes, together with reduced delays in the back line, has resulted in significant improvements. The details are presented in this paper.

Jan 1, 2000

Comparison of Grinding and Liberation Processes for Stalky Biomass Materials as a Prerequisite for Production of Energy Pellets with High Calorific Value Pelletising biomass, especially straw and stalky materials, requires a product specific size reduction and liberation. However, moisture content plays an important role in palletising and also affects the energetic properties of the biomass. The paper illustrates the characteristics of the mentioned type of biomass and specifies the necessities for production of energy pellets. Defined requirements for biomass energy pellets will be shown based on relevant standards. The work focuses on a comparative investigation of the straw fibres after grinding with hammer/impact mill and after the liberation of the straw fibres with twin-screw extruder (two different communition units). A traditional hammer mill as well as an hydrothermal process taking place in a twin-screw extruder were utilised. Results of the grinding and liberation of rye and wheat straw fibres are discussed based on a detailed particle characterisation (particle size and shape distribution). Besides high calorific value the main pellet quality parameters are mechanical stability, abrasion resistance and further combustion technical characteristics. The particle size distribution displayed optimum characteristics for the combustion processes to be carried out in a furnace. The durability of the pellets produced from straw fibres liberated with twin-screw extruder was comparatively better then that prepared with the straw fibres after grinding with impact mill. Particle size distribution, abrasion values and the strength characteristics showed a good correlation with each. The high presence of N and S would result in high NOx and SOx emissions, where as the high concentrations of Cl would corrode the furnace. These chemical properties of the straw would restrict its usage in small scale furnaces.

Sep 13, 2010

By G. V. Poropat

Roughness of a discontinuity may be an important factor influencing shear strength of the discontinuity. Traditionally, determining the roughness of a discontinuity surface and providing a numerical measure of the roughness has required considerable effort or specialised equipment. The development of new 3D imaging tools that are easy to use has provided effective fast and accurate means of creating 3D surface models from which roughness measurements can be readily obtained. These new techniques are versatile enabling a user to measure roughness along any desired profile and at any resolution up to the limit of the spatial subtense of a measurement on the discontinuity surface. This paper primarily reviews extensions to the use of 3D imaging that enable the measurement of roughness. Additionally we provide some examples of the measurements and examine some of the issues associated with extracting measures from the spatial data that will support estimation of shear strength.

May 1, 2009

By John B. Tieder

Arbitration is a legally recognized alternate litigation for the resolution of civil disputes. The parties agree, either before or after a dispute arises, to submit that dispute to an independent third party for resolution. The decision of that third party is binding on the parties. A decision of an arbitral tribunal, typically referred to as an "award," cannot be reviewed by a court except on very limited grounds, such as fraud. See, e.g., Va. Code 8.01-581.010. Indeed, an arbitral award is typically less subject to judicial review than the decision of a trial court, whose decisions are almost always subject to appellate review as a matter of right. Arbitration is typically the result of a contractual agreement between the parties to submit disputes to arbitration. On occasion, arbitration can be required by statute. For example, the California Department of Transportation requires the arbitration of all disputes arising under its contracts. Public Contract Code, Article 7.1 (§§10240-10240.13). There may be a question whether statutorily required arbitration is truly arbitration or an administrative law disputes resolution procedure. The significance of the difference is that the decisions of administrative law bodies are typically reviewable by a court of law as a matter of right while, as set forth above, arbitral awards are almost never reviewable.

Jan 1, 1988

Orebodies are defined in economic terms in that they must satisfy conditions determined by costs of mining, extraction and marketing before being so described. Despite this they have an essential chemical character as specialized products resulting from geochemical differentiation, and it is surprising that so little basic geochemical research has been carried out with respect to ore occurrence and that prospecting methods based on geochemical principles are not more widely applied.Many exploration geologists associate geochemistry with analytical techniques applied to the detection of dispersed traces of metals from actual orebodies. Geochemical research, applied to economic geology, goes far beyond this limited field and the purpose of this paper is to discuss aspects of such research and its use in formulating exploration principles.THE GEOCHEMICAL BACKGROUND TO MINERAL OCCURRENCE AND EXPLORATIONThe three aspects of economic mineral deposits to which geochemical research can be of use in determining ore guides are genesis, control of deposition and mode of dispersion from orebodies after emplacement. Prospecting for mineral deposits is primarily based on theories of ore occurrence which deal with the genetic and depositional influences controlling localization of ore. There are many such theories and they will not be discussed here as they have been adequately reviewed in geological publications. Some are based on differing argument concerning the same empirically observed associations of ore. In this respect it is perhaps fortunate that they are not always mutually exclusive as regards the...

Jan 1, 1960

By John Heter

An alum/sulfur deposit (USDA organic registered) was mined underground for alunite (K,Na) Al3 (SO4)2 (OH)6 from the early 1900s to the 1930s. It is now being mined as an open pit quarry. A larger assemblage of minerals is included with this method (Alunite, Potassium?Alum, Jarosite, Gypsum, Native Sulfur and K-feldspar). This assemblage of minerals provides the necessary requirements as a Volcanic Soil Conditioner Sulfur-Potash. Heart of Nature? Company has been marketing this product to farmers on the west coast as a (1) pH reducer, (2) soluble sulfur and potassium source for plant growth and (3) soluble calcium. Recently, a new market has been tapped. This product has been found to solve many odor, bacteria and algae problems faced in the dairy industry.

Jan 1, 2008

By Rajagopala Reddy Kallu

After the Sago and Darby No. 1 mine incidents, the new regulatory standards for the design of mine seals in underground coal mines of the United States require the mine seals to withstand higher explosion standards. This necessitated for the development of new design approaches and standards. For development of any new design standards or approaches a detailed understanding of effect of key influencing parameters on the stability of mine seal is a must. This paper attempts to address one of the factors, i.e. roof convergence, that play an important role in the stability of mine seal under explosion loading. Initially a couple of three dimensional numerical models were built and tested for different levels of roof convergence. These models confirmed that roof convergence has great influence on seal stability. A detailed study is undertaken, with some simple assumptions, to establish typical influence of roof convergence on the stability of mine seal under different levels of static explosion pressures. Three dimensional distinct element code 3DEC is used for this purpose.

Jan 1, 2007

By C L. Briend, O&apos

This paper presents the main features of coal mining in Japan, as determined by the author while attending the International Coal Conference in October of 1963. The general economy of the country is considered, and the requirements for coking coal are outlined. Statistics and comments on production and consumption are then given, with accompanying cost figures, and the characteristics of Japanese coal mining are compared with those of Canada. Mining methods and underground transportation are covered, with emphasis on undersea mining. Finally, a description is given of a visit to the Miike colliery, the largest in Japan. I T was my privilege to attend the International Coal Conference held in Tokyo in October, 1963, to meet many prominent members of the Japan Coal Association and to visit one of the major coal fields. This is probably the reason why I was asked to present this review of the coal situation in Japan. In doing so, it must be pointed out that I am not an expert in coal mining, that my

Jan 1, 1965

By J Kelly, C Kelsey

The Autogenous Kelsey Axial Displacement (KAD) mill is essentially a short retention time centrifugal mill, designed to effectively harness extraordinarily high concentrations of input energy for efficient particle size reduction. The mill which has an operating duty band extending from primary to ultra-fine also has the unique capacity to generate fine and ultra-fine products from single stage size reductions of either coarse or fine mineral feeds, in both wet or dry operating modes. This paper covers developments following a recent optimisation programme which confirmed that mill shell speed and the velocity differential between the shell and the rotating internal disc assembly tips could be optimised in relation to specific energy for a given feed rate and feed size providing the product size remains constant. Subsequent test-work further demonstrated the versatility of the mill with duties ranging from the removal of surface contamination associated with heavy mineral concentrate particles to the production of premium ultra-fine talc, from a single stage of size reduction. Open circuit grinding of a rougher gravity concentrate to liberate gold ahead of leaching also highlighted the scope for the application of low cost KAD milling for a range of hydrometallurgical feed preparation duties, which involve fine and ultra-fine grinding.CITATION:Kelly, J and Kelsey, C, 2013. Advanced media-free fine and ultra-fine grinding - The Kelsey axial displacement mill, in Proceedings MetPlant 2013 , pp 152-161 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By J. S. Peterson

Occupational noise-induced hearing loss (NIHL) has been recognized by the National Occupational Research Agenda (NORA) as the most common job-related disease in the United States. Roughly 30 million workers are exposed to excessive noise levels or toxins that are potentially hazardous to their hearing. The National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR)is investigating noise controls to reduce operator overexposures caused by haul trucks used in underground metal/non-metal mines. To identify the most significant contributors to the overall sound level, Source Path Contribution (SPC) analysis was conducted. Noise dosimetry and time-motion analysis were also conducted to quantify operator noise exposure. SPC analysis determined that, under high idle conditions, a source near a hydraulic pump mounted to the rear of the engine and the engine cooling fan were the major noise sources. The time-motion/dosimetry analysis showed that the operators accumulated more than 90% of their noise exposures while they were hauling ore to the dump site and traveling back to the load site unloaded.

Jan 1, 2012

By G. S. Maré

Tin plating operations are of a complex nature due to the many operational variables that need to be controlled in order to create a product of required quality. The work in this report lays the basics for the control of a halogen plating operation based on the DuPont tinplating set-up with regard to the chemical make-up of the plating solution, as well as operational variables such as temperature and current density. To evaluate these aspects of the process, a rotating cathode Hull-cell set-up was used. This allowed for a laboratory scale plating arrangement that simulates industry closely with regard to chemical and hydro-dynamic considerations. Typical industry accepted standards were obtained for the values of operational variables and a ?baseline? test was conducted employing these standards. All subsequent tests conducted were benchmarked against this baseline result. A large suite of results was obtained in which it was found that changes could be made to the industry accepted norm which would improve on the stability of the operation and therefore the quality of the final tin-plated product. Examples of these results are: an increase in stannous tin concentration, an increase in sodium chloride concentration and a slightly elevated plating temperature. In addition, conditions were found that must be avoided to prevent instability and poor product quality.

Jan 1, 2010

By L. W. Pommier, F. B. Brien, A. K. Bhasin

In the field of mineral processing, although many operations are applied to suspensions of ore particles in fluids, there is a lack of fundamental knowledge relative to the flow resistance encountered by immersed bodies moving through solid-liquid suspensions. Previously proposed equations, based on the Ostwald-de Waele (power-law) model for non-Newtonian fluids, are exam ined in the turbulent flow region relative to a number of pertinent variables and their effects on the movement of immersed bodies. As more knowledge is acquired in regard to the effects of suspension variables on the rheological properties, useful relationships may be proposed to allow predictions of conditions to achieve optimum results for engineering purposes. In the field of minerals processing, many operations are applied to suspensions of ore particles in fluids. The differential movement of solids of various sizes and densities in suspensions is of utmost importance to gravity concentration, wet classification, flotation, hydrometallurgy, and pipeline transport of solids. The subject is also of importance to other branches of engineering; for example, those involved with soil mechanics, ceramic slips, and oil-well drilling fluids. There is a lack of fundamental knowledge relative to the flow resistance encountered by immersed bodies moving through solid-liquid suspensions. The problems encountered in the direct application of the well-known Stokes and Newton's Laws to non-Newtonian systems have been examined in a previous paper.' Equations were proposed based on the Ostwald-de Waele (power-law) model for non-Newtonian fluids. This present paper examines these equations in the turbulent flow region relative to a number of pertinent variables and their effects on the movement of immersed bodies. It is thought that, as more knowledge is acquired as to the effects of suspension variables on the rheological properties, useful relationships may be proposed to allow prediction of conditions to achieve optimum results for engineering purposes. The purpose of this paper is to make an initial assessment of the nature and magnitude of pertinent suspension variables. In order to avoid too voluminous a document, the examination of kinetics and mechanisms will be omitted at this time. THEORY A Newtonian fluid is defined as a fluid in which the stress is proportional to the rate of strain, 2 i.e.: H = viscosity; see Table I. for list of symbols The following equations are conventionally used to assess the motion of spherical particles moving under laminar and turbulent flow conditions through Newtonian fluids: When these relationships are applied in practice to suspensions, the liquid density is substituted by a composite suspension density, and viscosity is usually taken as that of the suspending liquid or an approximated "apparent viscosity." However, suspensions are non-Newtonian in character3 and thus, more than one viscosity parameter is required to describe their behavior. A number of models have been proposed for non-Newtonian fluids;2,4 among these the simplest is the Ostwaldde Waele or power-law model for incompressible fluids which for one dimensional flow may be reduced to:

Jan 1, 1970

Hydraulic backfill is generally retained in slopes using permeable barricades. Mitchell et a! (1975), Mitchell (1992) and Grice (1989) have shown that under normal drainage conditions, barricades experience low levels of loading. Cowling et a! (1988) have also shown that barricades are susceptible to piping failures if excess water has ponded on the upper backfill surface and if leakage of backfill from the barricades has occurred. During 1997, six hydraulic backfill barricades failed in four different Australian mines. Fortunately, in each case, the quantity of backfill slurry released was small, and no injuries to personnel nor damage occurred. Detailed investigation of two of the incidents showed that the primary cause of failure could be attributed to the delivery of excess quantities of transport water from the low-density slurry. For each of the incidents investigated there was evidence of the development of piping failures, which resulted in hydrostatic loading conditions on the barricades from the ponded water on the upper backfill surface. The circular failure surfaces in the barricades were characteristic of the application of point loading Conditions.

Jan 1, 1998

By T. Braun, J. Parker

On June 25, 1999, BHP Billiton (BHPB) announced the suspension of operations at the BHP Copper Inc.(BHP) San Manuel copper mine in Pinal County, Arizona. Subsequent to this announcement, BHPB aggressively pursued a number of alternatives for the underground mine and open pit facilities, including continued curtailed operations, sale to a qualified mining operator and closure of the property. After consideration of these various alternatives over a 2.5-year period, BHPB announced final closure of the mine site on January 15, 2002.This paper describes how the BHPB charter and HSEC policy apply during the closure process.

Jan 1, 2004