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By S. Goodfellow, J. C. Ordóñez-Calderón, K. Esmaeili, N. Houshmand

A good understanding of the hardness of ore being handled and processed in a mining operation can significantly improve operational efficiencies by providing valuable data to support decision-making through the mining value chain (drilling, blasting, comminution). This study presents the results from the application of Machine Learning (ML) to predict rock hardness using various geophysical and geochemical features. Core samples from a mine site were logged using a multi-sensor core logging system. Measurements including ultrasonic p-wave and s-wave velocity, elemental concentration via portable XRF, and Leeb Hardness, were measured every 2 cm along the length of the core. The ML model was set up to predict the Leeb Hardness using the elemental concentrations and ultrasonic velocities as predictors. The Leeb Hardness values were grouped into three bins and used as a classification target for the ML models. Various ML models, including linear regression, support vector machines, decision tree, XGBoost, Random Forest, K-Nearest Neighbors, and Naïve Bayes were tested. The model performance demonstrated that the Random Forest and XGBoost models produced the highest accuracy of 74-91%. Random forest and XGBoost were then selected to perform regression models to estimate a Leeb hardness value rather than a hardness class. These models were able to estimate the Leeb hardness value by 4.57-4.87 % error.

Mar 2, 2022

By Stanley J. Gasior

Most bituminous coal mined near Eastern industrial areas requiring high Btu pipeline gas is caking and therefore unsuitable for fixed-bed pressure gasification by present techniques. If the caking property of such coal can be destroyed the resulting fuel can be gasified in a fixed bed at pressure with steam and oxygen as a preliminary step in making a high-Btu gas. To find a practical way to convert strongly caking coals of granular or small lump size to noncaking fuel was the object of this study. In previous work strongly caking coals of 1/8- to 1-1/2-inch size was converted to a noncaking coal char by treatment in a static bed in about 3 hours [1/]and coal of 18-100 Tyler mesh in a fluidized bed in about 5 minutes.[2/] An inert gas such as `steam, nitrogen, carbon dioxide, or a mixture of all three with a small amount of oxygen was used in both studies. In our work a strongly caking bituminous coal from the Pittsburgh seam of 4-8 Tyler mesh size was converted to a-noncaking form in free-fall in about 2 seconds by dropping it through a countercurrent flow of steam containing 4 to 7 percent oxygen at 1,150°-1,200° F and 300 psig. This method should also be applicable to smaller-sized material.

Jan 1, 1965

By J. Killian, S. Cox

Many questions exist within the geotechnical industry as to the applicability of Strength Reduction Factor (SRF) values to the design acceptance criteria (DAC) of mining operations. There are many factors that contribute to changes in the SRF estimate, some of which are numerical (e.g. dilation angle) and some of which are geometric (e.g. model grid size)[1]. Numerous studies have confirmed equivalent values of SRF and FOS are found for soil slopes of limited height as presented in, [2] and [3]. However, significant deviation of the SRF value was observed for highly cohesive materials (rock slopes) of heights typically encountered in mining, [4]. This paper builds on the work presented in [4], providing a more rigorous examination of the modeling parameters that control the SRF estimate. The failure mechanism assumed for this study was a simple circular shear surface in a uniform material. Both LEM and numerical methods are suited well for analysis of this failure mechanism. A parametric study was completed to evaluate and test the relationships of key numerical variables that affect the estimated value of the SRF using Itasca’s Fast Lagrangian Analysis of Continua (FLACTM) software. The effect of groundwater has been tested and may be significant but is not presented as part of this body of work for brevity and simplicity of presentation.

Mar 2, 2022

By David A. Lee

It was estimated in Chemical Week1 that the uranium fuel requirements for the U.S. Electric Utility Industry by the mid 1980's would be about four times that-of what it is today. This corresponds to approximately 45,000 tons per year of 'yellow cake' - of which a good portion is represented by ammonium diuranate - vs. the 11,700 ton total estimated for 1975. Perhaps just as significant is the 40-fold increase in thirty years projected for the entire world since 1970. Thus by the year 2000. 'yellow cake' production could be in the order of [3]50.000 short tons annually.2 'Yellow cake', so named because of its inherently bright yellow color, is a finely divided precipitate that can be formed after the leaching step when refining uranium ores. Feed solids enhancement then occurs to at least 50% by weight using filters or centrifuges This is followed normally by drying and then calcining with the conversion of ammonium diuranate to triuranium octoxide represented by the following equation: [9 (NH4)2 U2 07 heat 14 NH3 7 + 15 H2O7 + 2N2/ + 6 U308 4] Theoretically, assuming 100% conversion every 100 kgs. or 100 lbs. of ammonium diuranate will result in 90 kgs. or 90 lbs. of triuranium octoxide.

Jan 1, 1976

By Edwin H. McKee

Eruption of rhyolitic ash-flow tuffs in the area of the McDermitt (Cordero) caldera began about 17.4 m.y. ago and continued for about 1.5 m.y. During this period of silicic eruptions, a circular area about 30 km in diameter collapsed to form a caldera that subsequently filled with sedimentary and volcanic rocks. 3 A total of more than 200 km of silicic rocks was erupted from the volcano. The final phase of igneous activity, about 15.5 m.y. ago, included resurgent doming and intrusion in the central part of the caldera. Three to 4 m.y. later +I2 m.y. ago), hydrothermal solutions using the northern part of the caldera ring fractures as conduits deposited cinnabar, pyrite, alunite, and other minerals in tuffaceous lake beds and volcanic rocks accumulated within the caldera. The ore-forming solutions may have been a residuum from the silicic magma or connate water or ground water heated by the still-hot resurgent magma in the central part of the caldera. The source of the mercury has not been identified. Later oxidation of the sulfide minerals and redistribution of the supergene minerals corderoite, several mercury nitro-oxychlorides, marcasite, iron, and titanium oxides in the sedimentary rocks account for most of the newly discovered ore body at Cordero.

Jan 1, 1976

By G. C. Knutsen

The Post deposit is located in Eureka County, Nevada, about 37 km (23 miles) northwest of the town of Carlin. Post occurs on the Carlin Trend, a northwest alignment of 14 major gold deposits, each containing more than three tonnes (t) (100 000 ounces) of gold. Deposits of the Carlin Trend are epithermal, sediment-hosted, disseminated gold occurrences, collectively containing more than 622 t (20 million ounces) of gold. Three major gold producers active on the Carlin Trend are Newmont Gold Company (NGC) (12.4 t/400 000 ounces of gold per year), Western States Minerals Corporation (WSMC) and Pancana Minerals joint venture (1.56 t/50 000 ounces of gold per year), and Dee Gold Mining Company (1.4 t/45 000 ounces of gold per year). The Carlin Trend has also been referred to as the Lynn-Railroad Mineral Belt. This district is characterized by open-pit mineable, micron-sized gold, hosted in Paleozoic sedimentary rocks. Six geological subdistricts comprise the Carlin Trend, each characterized by differences in host lithology, structural controls, alteration assemblage, or style of mineralization. The six geologic subdistricts include, from south to north, Bullion (Railroad), Rain, Maggie Creek, Lynn, Bluestar-Goldstrike, and Bootstrap. With the exception of the Bullion subdistrict, which was primarily a producer of base metals, each sub-district contained mineable reserves in excess of 31 t (one million ounces) of gold.

Jan 1, 1987

By Steven J. Van Kauwenbergh, Talaat A. B. Lawendy

Batch laboratory-scale beneficiation tests were conducted on four high-iron phosphate samples. These samples included sedimentary ores (Tilemsi Valley, Mali and Tahoua, Niger), a sample from an igneous phosphate deposit (Matongo, Burundi), and a fine-grained phosphatic iron ore processing residue from Chile. The Matongo phosphate deposit occurs as a thick (up to 80 m) residual blanket of P205-enriched soil over solid parent rock (carbonatite and associated rock types). Although the Matongo deposit is an igneous deposit, ore from the deposit can be subjected to beneficiation treatments commonly used to treat sedimentary rocks. The beneficiation flowsheets designed to process these diverse ore types involve attrition scrubbing, size classification, and flotation. At the best flotation conditions tested, phosphate concentrates assaying 32.0%-39.0% P205 and 1.0%-1.5% Fe2O3, were obtained at 64.2%-82.2% overall P2O5 recoveries from run-of-mine (ROM) ores containing 9.2%-28.6% P205 and 5.9%-16.1% F,20,. A cleaner phosphate concentrate assaying 33.1% P205, 1.8% A1203, and 3.3% Fe2O3 at 53.4% overall P205 recovery was obtained from the phosphatic iron ore residue that originally contained 4.5% P205, 8.0% A1203, and 17.6% Fe2O3.

Jan 1, 1993

By G. M. Wilemon, B. J. Scheiner

The Bureau of Mines conducted investigations on extracting phosphate values from fine-particle wastes generated during the mining and beneficiation of phosphate ore by leaching dried wastes using a H2SO4-methanol mixture. Although phosphatic clay waste contains up to a third of the phosphate originally present in the ore, recovery of these values represents a significant challenge due to the fine grain size of the material, the particles averaging less than one micrometer in diameter. Waste samples obtained from two Florida producers yielded phosphate extractions of 71 and 84 pct, respectively, when leached under ambient conditions and at a stoichiometric acid ratio of 1.4:l. Elevated temperatures did not improve the amount of phosphate extracted. Undesirable A12O3, Fe2O3, and PlgO impurities were largely rejected; higher grade wastes gave acids that meet established industry impurity standards and lower grade samples yielded acids that marginally fell short of the standard. Separation of the crude acids from the insoluble residues was accomplished via vacuum filtration through either filter paper or commercial filter cloths. Both filtration rates and solids retention were improved by the addition of 0.5 lb/ton of poly(viny1 acetate) (PVAc) or poly(ethy1ene oxide) (PEO) to the methanol-acid slurries. These results show potential for substantially increasing the reserves of an important domestic resource.

Jan 1, 1989

By H. Köse, C. Tatar, C. Helvaci, F. Simsir

The Çayirhan coal basin is located 124 km (77 miles) west of Ankara,Turkey. With approximately 520 Mt (570 million st) of lignite reserves, the Neogene Çayirhan basin is one of the important coal districts of the central Anatolia region. The Çoraklar formation consists of crossbedded sandstone, channel fill conglomerates, mudstones, carbonaceous shales and volcanoclastic pebblestones, which are fluvial in origin. The lower and upper lignite seams occur, respectively, in the lower and the uppermost parts of the Çoraklar formation. The lignite deposits are in the Çayirhan and Koyunagili portions of the Beypazari Neogene basin. The Çayirhan coalfield consists of lower and upper lignite seams. The lower lignite seam does not outcrop at the surface. Its lateral discontinuity and relatively low sulfur content, plus sedimentologic and stratigraphic features of the associated sediments, indicate a fluvial origin. Thus, the lateral spreading and geometry of the lower lignite deposits were controlled by the channel, flood plain and well drained marshes of a fluvial system. The mining method employed at Çayirhan is the fullymechanized, retreat, working longwall with caving system. Due to ventilation, haulage and tectonic conditions, panel lengths from 0.6 to 1.7km (0.4 to 1.1 miles) are chosen, and 220-m (720ft) face lengths are used. The annual coal production is 2.2 Mt (2.4 million st).

Jan 1, 1994

By P. Eng. Daniel Kelly

INTRODUCTION The Astoria property is located in the prolifically mineralized Abitibi greenstone belt and is one of the most advanced projects presently under development by Yorbeau Resources Inc. This property, which hosts the Astoria gold deposit, is located in the southern part of Rouyn township, Abitibi area, Quebec, 4 km south of the city of Rouyn-Noranda (Figure 1). The Astoria deposit has been the subject of underground development for over a half century, beginning with Granada Rouyn Mining Co. in the 1930's and followed by Astoria Rouyn Mines Ltd. in the 1940's. Yorbeau Resources Inc. acquired the property in 1984 and has, since then, conducted numerous exploration programs on this gold deposit. The diluted reserves of the Astoria deposit are estimated at 1,3 million metric tons grading 6,14 grams of gold per metric ton (1.4 million st at 0.18 oz/st). This reserve figure is based on the results of surface and underground exploration carried out from January 1986 to June 1987 and includes ore in the proven, probable and possible categories. This paper is divided into two sections. The first part includes a summary of the geological environment including a description of the gold bearing zones and a short discussion on wall rock alteration. The second part of this paper reviews the underground work and the objective of the ongoing exploration program.

Jan 1, 1988

By David M. Sullivan

Jim Walter Resources, Inc., (JWR) a division of Jim Walter Corporation, has 5 underground coal mines in Central Alabama varying in depths from 400-2500 feet. Gas Chromatography plays a vital role in safety and production at each mine. Chromatographic data is used to monitor working areas for safety and proper ventilation and to control the quality of extracted methane for sales purposes. Instruments have a1 so been employed during mine rescue operations. JWR's first Gas Chromatograph (GC) was installed in April 1984 to monitor gob gas taken from longwall gob areas and sold based upon BTU value. The GC allows maximum extraction rate of the gas within the quality guidelines. By late 1985, another system was purchased and both units were upgraded to perform an analysis of indicator gases which may appear during mine emergencies. Each unit has the ability to detect and measure the following gases at almost any level ; Oxygen (021, Nitrogen (N2), Methane (CH4), Carbon Dioxide (C02), Hydrogen (HZ), Carbon Monoxide (CO) , Ethylene (C2H4), Ethane (C2H61, Acetylene (C2H2) and a composite of hydrocarbon threes and above (C3+). The analytical run is accomplished in less than ten minutes and is completely automated. This report will introduce Gas Chromatography as applied by Jim Walter Resources for the analysis of underground mine air.

Jan 1, 1987

By Furuyama Takashi, Mori Sukeyuki, Hara Tsuyoshi, Fukushima Yujin

In mineral processing practice, flocculation is largely established as an engineering technique of waste water treatment and the study of parameters increasing the settling velocity of particles is still of great importance to improve the process. Further investigations were made using quartz (Q89) and fluorite samples (F91) which included 58.8% and 65.8% of -2.3 µm particles respectively. In all the experiments the flocculation phenomena were observed varying the pH value of the aqueous suspension. In contrast to quartz particles (Q89) which did not flocculate for all pH values, it was, noticed that fluorite particles (F91) flocculated in the alkaline range of pH over 11. With an aqueous suspension containing equal quantities of Q89 and F91, a hetero-flocculation of particles was observed at a range of pH below 10. In this case, the maximum floc size of the hetero-flocculation was 37.0-26.2 µm This size was about three times larger than when quartz (Q84) and fluorite particles (F85) were used with 32.4% and 40.4% of -2.31 µm particles respectively. Besides, in the experiments using Q89 and F91, the maximum size of hetero-flocculated single particles was found to be 6.54 µm instead of 3.27 µm as obtained with Q84 and F85.

Jan 1, 1995

By D. Gu

Breakage of rock by machine is one of the major methods of excavation. With the development of modern engineering techniques, the advantages of using this method have become even greater. Improving efficiency and reducing the cost of rock breakage is the main goal of mechanizing the rock-breaking operation. For a given stratum, the efficiency of a machine excavation depends, to a large extent, on the design and method of application of the tools used. In a planetary cutter head, the subcutter heads move like planets around the main drive shaft. The general structure of the cutter head is shown in Fig. 1. As shown in this illustration, the main drive shaft (1-1) is connected to the tie bar (1) and, thereby, to a gear(5) that meshes with a fixed-gear ring(2). The subcutter head (4) is rigidly connected to the gear (5) by the subcutter-head axis (2-2). When the main drive shaft (1-1) rotates, the subcutter head (4) rotates around the axis (2-2), under the action of the tie bar and with the help of sleeve pipe (3).At the same time, axis (2-2) also rotates around the main shaft (1-1). As shown in Fig 1, is the angle between the main shaft and the subcutter-head axis.

Jan 1, 1995

By Roy Norcross

For the past few years Caro's acid has been used for the treatment of cyanide containing slurry effluents, providing a feasible alter­ naive to other slurry treatment processes including !NCO SO2 / Arr and ferrous sulfate. Presently, mines using Caro's acid gen­erate their own Caro's acid onsite making a relatively low quali­ty product. It was at this point where we, at Degussa Corporation, decided to focus our efforts on engineering a Caro's acid genera­tor capable of cost effectively producing a high quality Caro's acid solution, thus reducing operating costs significantly. Caro's acid or peroxymonosulfuric acid is not a new chem­ical nor is it new to Degussa. The product was named after Heinrich Caro (1834-1910), a German chemist who first described its synthesis and its oxidizing properties in 1898. Degussa has been producing the potassium salt of Caro's acid as the triple salt, 2KHSO5 - 2KHSO4 - K2SO4, called Caroat®, for over 30 years. Caroat® is used for household and denture cleansers, as a bleaching agent in dish washing detergents, in printed circuit board etching and for cyanide destruction in the plating industry. From our experience in producing Caroat® Degussa developed its new Caro's acid based DegOX™ technology for the treat­ment of cyanide containing effluents from gold and silver mines.

Jan 1, 1996

By William C. Cooley

Modern tunnel boring machines are subject to excessive cutter wear and bearing failures when used in hard and abrasive rock. In very hard rock, the high cost of cutter and bearing replacement, combined with slower excavation progress, make it more economical to drive tunnels by conventional drill and blast methods. The use of high pressure water jets to break rock provides a promising alternative. Experimental data indicate that the specific energy (the energy expended per unit volume of rock broken) decreases as the water jet pressure increases. Continuous jets are generally limited to pressures below 100,000 psi, whereas pulsed jets from a water cannon can attain much higher pressures. Therefore, the Federal Railroad Administration of the U. S. Department of Transportation has sponsored the design (Ref. 1 & 2) and the fabrication and testing (Ref. 3 & 4) of a water cannon to determine its effectiveness in rock disintegration at very high pressures. This paper reports the results of laboratory tests with pulsed jets against large rock samples at pressures of 125,000 to 650,000 psi and field tests against dolomitic limestone and granitic gneiss at pressures near 450,000 psi. Although initial tests were made with a small nozzle, operating at off-design conditions (Ref. 4), this paper only covers results with the full-size nozzle, including 55 laboratory test shots and 67 field test shots.

Jan 1, 1974

By Yuexin Han

The characteristics of comminuted hematite products using a high pressure grinding roller (HPGR) and conventional jaw crusher (JC) were comparatively studied by screening, optical microscope, scanning electron microscope (SEM) and Brunauer, Emmett and Teller (BET) techniques. Major properties investigated included product size distribution, particle cracks, specific surface areas and pore volumes. Results showed that in a closed-circuit operation with a screen opening of 3.2 mm, the HPGR and JC gave a similar P80, but the HPGR achieved a more uniform size distribution, more fines and a higher crushing efficiency. Three modes of cracks were identified, namely transgranular cracks, innergranular microcracks and intergranular microcracks. Transgranular cracks originated from shearing breakage. Innergranular and intergranular microcracks were generated by HPGR via the two main nonrandom breakage forms, preferential breakage and interfacial breakage, depending on their respective ability to endure stresses when mineral phases (particles) were loaded against each other. The BET values for the same-size fractions showed that HPGR products gave higher specific surface areas and more pore volumes than JC products. This indicates that HPGR-crushed products are easier to grind because of their high porosity and extra cracks.

May 1, 2012

By Dan Ifrim, Andre Solecki

Tunneling could be a major challenge to tunneling contractors as tunneling operations can be seriously affected by the Tunnel Boring Machine (TBM) performance. Specifying the appropriate TBM methodology, selection of systems and features, is critical for managing tunnel risks and contribute to successful tunneling project. The paper analyzes tunneling records from the recently completed City of Toronto’s Ashbridges Bay Treatment Outfall tunnel project and underlines the righteous selection of the TBM type and associated TBM systems in achieving good advance rates during tunnelling and managing project risks. The paper intends to draw attention of a few aspects of TBM technical specification importance and highlight the lessons learned from this process.

Jun 13, 2023

By Ole Bernt Lile

The well-known method of C. Schlumberger, Mise a la masse, has become a popular method again in ore exploration in Norway after many years of dominance by EM methods. The principle of the method is to place a current electrode within a conducting ore body and remove the other electrode to a great distance. (Figure 1). Often it is convenient to place a return electrode on each side of the area explored. The method is best suited for ores that have a conductivity contrast, relative to the host rock, of several orders of magnitude. The potential drop within the ore itself may then be neglected and the ore contact against the rock may be regarded as an equipotential surface. One may say that the ore body is electrically charged. Therefore, in Norway the method is now most often called the Charged Potential Method (abbreviated CP). The most usual way to present data obtained by CP, is to draw equipotential lines based on potential values measured in profiles on the surface. Such a potential map gives an immediate picture of the outcrop of the ore and also indicates disturbing conductors in the neighborhood. It may also be useful to look at the potential profile and its horizontal gradient along the strike axis of the potential map. These profiles may give information about the strike length of the conductor. Figure 2 shows the theoretical profiles of potential and gradient along the axis of the potential picture on the surface over a charged line plunging 15 degrees. It may be seen that the maximum of the gradient curve clearly indicates the lower end of the conductor. Figure 3 shows the corresponding pro- files over a charged line plunging 45 degrees. In this case, it is not possible to see an indication on the curve of the lower end. Only curve fitting could help interpretation in this case.

Jan 1, 1975

By Judson G. Brown

In order to filter small amounts of fine slimy solids the reversible cake-filtration process was developed. The filterable solids contents lion in feeds can range from less than 1 ppm up to about 5%. The relative advantages of this process, are usually the greatest in the range of 0.05% to 1.0% filterable solids. Filterable solids that average in particle size about 20 microns& are non-compressible are very easy for this filtration process. Some feeds have been all sub-micron in particle size. A 1/8 inch thick cake is considered to be very thick. The usual cake is between 13/2 and 1/16 inch thick. A new line of injection molded plastic filter plates were developed for use with the reversible cake filtration process. The first commercial sized installation of this system was made 3 years ago in the Wakefield Y.M.C.A. swimming pool. Over 70 filters ranging in size from one plate to 63 plates have been produced. In addition to the process advantages there are the low cost and corrosion resistance advantages of the plastic plates.

Jan 1, 1962

By M. I. Brittan

A technique has been developed that analyzes routine mill operating data to determine the key operating parameters responsible for gold losses to tails. These parameters represent the prime operating variables having a dominant effect on gold recovery. The technique quantifies these effects for the specific plant being analyzed, providing a tool to optimize recovery and costs and so enhance the mine?s cash flow. The quantitative relationships generated will be different for each ore and plant: every case is site-specific and has to be treated on its merits. Examples are provided to illustrate the considerable metallurgical and financial benefits which can be realized from optimization. The examples are taken from case studies of mills in four major gold mining districts of the world.

Jan 1, 2010