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By Yousef Ghorbani, Abolfazl Danesh, Fatemeh Kazemi, Ataallah Bahrami, Morteza Abdollahi

The abstract highlights the impact of flocculants used in the middle thickener of a copper-molybdenum plant on both process water quality and molybdenite floatability. The study investigates the effect of a starch-based flocculant (wheat starch) on the efficiency of the middle thickener and molybdenite flotation. The findings indicate that the presence of starch influences the settling behavior of particles with different shapes, and the dosage of starch affects both molybdenum recovery and the presence of copper minerals in the molybdenum concentrate.

Mar 7, 2022

By B. Samanta, S. Bandopadhyay

Ore grade modeling of a placer gold deposit is considered a challenging problem even today. Typically, gold-bearing deposits show extremely erratic and unpredictable grade variation. This is principally because of isolated occurrences of gold metal within a few high-grade pockets. Because of sporadic fluctuation of high-gold-grade distribution, the overall spatial continuity of the deposit becomes poor. This type of variation is often described by a lognormal or highly skewed frequency distribution, and the spatial continuity of the deposit is characteristically represented by a variogram model that exhibits a high nugget component. Further complicating the matter is the sparse availability of drillholes to capture such erratic variation. Due to the prohibitive cost of drilling, gold grade and reserve estimations are typically carried out using insufficient exploratory data. Use of a traditional estimation technique on limited data often produces an unreliable ore grade model. Kriging and its nonlinear variation, lognormal kriging, are frequently used in gold deposit modeling (Rendu, 1979; Journel, 1980); however, kriging is flawed by the smoothing effect. Moreover, though kriging is known to be globally unbiased, it is not free from conditional bias. As a result, if a deposit is modeled using the traditional kriging technique, a high-grade zone can be predicted to be a low-grade zone and vice versa. Predicting high grade as low grade results in a missed opportunity to exploit profitable ore. On the other hand, prediction of low-grade ore as high-grade ore might result in financial loss for a mining operation. Thus, the use of kriging for ore grade mapping of a gold deposit may not be recommended. Estimation techniques (including kriging) can produce an estimate with minimum error in a minimum-error variance sense. However, no matter which estimation technique is used for grade modeling of a highly erratic deposit like gold, the error margin is bound to be high. Therefore, any grade prediction made for an unknown location is associated with high uncertainty. Since various mine-planning operations, including derivation of grade tonnage curve, pit design and economic analysis of the deposit, are based on estimated grade rather than true grade, a mining project evaluation that depends upon estimation will be subject to considerable risk. Thus, the successful design of a mining project not only depends upon accurate grade estimates, but also upon accurate assessment of uncertainty, for predictive grade is equally important. Although the kriging standard deviation is used as an indicator of uncertainty for prediction, it is flawed by characteristics related to a data-independence property. This study, therefore, investigates the stochastic simulation technique of conditional simulation for ore grade modeling of a placer gold deposit at Nome, Alaska. It is expected that the research will provide a better solution to ore-grade deposit modeling than the kriging technique because (1) conditional simulation preserves spatial continuity as well as reproduces the data histogram, thus avoiding the smoothing problem; and (2) generation of multiple realizations helps to accurately quantify the uncertainty about grade values in the deposit.

Jan 1, 2009

By Fengyu Ren, Kunpeng Yu, Gideon Chitomb, Qiangqiang Gao, Liqiang Ma, Jiangtao Zhai, Ichhuy Ngo

The penetration of rock fragments of overlying strata causes advanced ore dilution during drawing. The results of numerical and physical experiments showed that the proposed numerical simulation was applicable and the microscopic parameters of the model were reliable. The penetration under the variables of particle diameter ratio, density ratio, overlying strata thickness, and particle morphology was clarified. The penetration was quantitatively characterized by the discharge amount and the dilution rate. The experimental results showed that the diameter ratio and density ratio had a significant influence on the penetration. On the irregular shape of particles, the penetration is weakened. The overlying strata thickness had little effect on the penetration. This study could provide a theoretical basis for the full section uniform drawing, avoiding advanced ore dilution and further optimization of recovery rate.

Nov 13, 2023

By Mehmet Ali Recai Önal, MAHMUT CAMALAN

Mineral liberation is one of the primary objectives in comminution circuits for the downstream separation of valuable minerals. Breaking minerals through their grain boundaries (grain-boundary breakage) enables mineral liberation in their natural grain size, removing the need for intensive grinding. This study aimed to evaluate if gaseous carbon dioxide, oxygen, or hydrogen can be used as grinding additives to promote the liberation of chromite grains by grain-boundary breakage. For this purpose, chromite ore particles in the −9.53 + 6.35 mm size fraction were pretreated by exposing them to carbon dioxide, oxygen, or hydrogen flow. Then, the untreated and pretreated samples were broken in a drop-weight tester under the same conditions. Finally, the graderecovery plots of chromite grains in the selected progeny size fractions and the overall progeny distributions were measured and compared. Pretreatment with carbon dioxide flow was found beneficial for grain-boundary breakage. It significantly enhanced the liberation of coarse chromite grains along with the overall progeny fineness. EPMAanalysis showed that the adsorption of carbon dioxide seems to reduce aluminum concentration at grain boundaries, which could be the reason for grain-boundary weakening. These results suggest that carbon dioxide can be used as a grinding additive, reducing the carbon footprint of the mining industry.

Oct 29, 2020

By Roger Malmström, H. Heden, Kjell Lidin

INTRODUCTION LKAB was formed at the turn of the century when the railways between the ore fields and harbors were built. The mines are situated north of the Arctic Circle in Sweden. Kiirunavaara is the largest mine, with a pro¬duction capacity of approximately 30 Mt/a. Malm¬berget has a capacity of about 12 Mt/ a. Both are under¬ground mines. Svappavaara, the only opencast mine currently in operation, has a capacity of about 4.5 Mt/a. The ore harbors are at Narvik for the Kiruna and Svappavaara mines and at Lulea for the Malmberget mine (see Fig. 1). Production in the form of finished products is shown in Fig. 2a, b, c, and d. Due to poor ore markets in re¬cent years, production and shipments have been cut back, but there was a positive swing in 1978. LKAB has been 96% state-owned since 1957. In addition to the iron mines in northern Sweden, LKAB has subsidiaries in central Sweden which produce sulfide ores, quartz sand, and uranium (Fig. 3). The mining methods employed are opencast bench stoping at Svappavaara and sublevel caving at Kiirunavaara and Malmberget. GEOLOGY The Kiirunavaara ore body is 4000 m long and av¬erages about 90 m wide, with variations in width from a few meters to around 150 m. The ore has been ex¬plored by deep drilling down to about 1000 m, but mag¬netic measurements indicate a depth of at least 1500 m. The Kiirunavaara ore is oriented in a north-northeasterly direction with a number of ores in the boundaries be¬tween the wall rock types. The ore in Kiirunavaara is mainly a fine-grained magnetite with a varying content of fine-grained apatite. The apatite content of the ore decreases with increasing depth. The other ores are all apatite-bearing and a couple are hematite ores (Fig. 4a, b). The ores are sedimentary, tilted, and tectonically de¬formed. They have a lateral dip of 0.87 to 1.2 rad (50 to 70°). The contacts between ore and wall rock are distinct and sharp, but both the hanging wall and the footwall are brecciated and impregnated with magnetite. The footwall of the Kiirunavaara ore consists of syenite porphyry with a low quartz content and rela¬tively good strength; the hanging wall consists of quartz porphyry. Both types are known as Kiruna porphyries. The ore at the boundary with the hanging wall is often rich in kaolin. There are a few veins of syenite porphyry running through the ore, which has a few major faults (Fig. 4c, d). There are two sharply delineated ore grades in Kiirunavaara: low phosphorus ore with less than 0.1 % phosphorus (about one-third of the ore) and high phos¬phorus ore with greater than 0.5% phosphorus. The iron content is 67% in the low phosphorus ore and 60% in the high phosphorus ore. These ore types are sold as different grades and so are kept separate during mining. MINING AT KIIRUNAVAARA The Kiirunavaara and Luossavaara ores were first mined using opencast bench stoping in 1902. When mining costs rose owing to higher waste removal, under¬ground methods were adopted. In the mid-1950s, the ores were still being mined on the surface at the same

Jan 1, 1982

By Michael S. Moats, John Bailey Fletcher

The performance of grinding media can be misrepresented in marked ball wear tests due to galvanic interactions between dissimilar media. The possible galvanic interaction of media materials during marked ball wear tests has not been adequately explored. Corrosion rates and potentials of modern high carbon steel and high chromium white iron grinding media materials were measured using electrochemical testing as a function of pH and chloride content in a simulated mill water. The results replicate previous research with the high chromium white iron sample being more noble (higher corrosion potential) and corrosion resistant (small corrosion current) than high carbon steel. Using the experimental data and corrosion theory, the effects of galvanic coupling on corrosion rates were calculated to examine what could happen during a marked ball wear test or when a mixed media charge is present. This analysis indicates that high carbon steel can cathodically protect high chromium white iron leading to significant decreases in the corrosion rate (up to 99%) of this material during marked ball wear tests. The magnitude of the protection is a function of the pH of the mill water.

Dec 21, 2022

By Zhiyuan Ma, ZUI WANG, Xincheng Hu, Jianwei Cheng, Junhong Si, Yi Qin, Gao Ke

The harmfulness and destructiveness of mine gas explosion is quite serious, which is the first of all kinds of coal mine disasters. Once the gas explosion occurs, it could instantly generate explosion shock waves, high temperature airflows, and disaster gases, which cause the destruction of underground ventilation structures, disruption of airflow direction in a mine ventilation network, and miners’ deaths by asphyxiation. As an important barrier to prevent the spread of accidents caused by the gas explosion, the safety and reliability of the mine seal affects the mine’s production and the health of workers. Due to the demands of coal mine production and transportation, a large number of longitudinal and horizontal roadway networks have been developed underground. There are not only many flat and straight roadways in the complex roadway network structure, but also a large number of different types of bifurcations and bends. Once a gas explosion occurs, the impact of the blast waves on the mine seal after passing through the complex path is difficult to determine. Therefore, this paper establishes a numerical model of bifurcated and cornered roadways and studies how the impact of gas explosion shock waves on the structure of sandwich mine seal after passing through different types of bifurcated and cornered roadways. The damage state of sandwich mine seal is analyzed. The researching finding could prevent and manage the spread of gas explosion disaster, and improve the disaster mitigation of mine explosion accident.

Jul 11, 2023

The past four years since the 2008 MINExpo have been a roller coaster ride for the mining industry, with highs and lows and everything in between. One of the natural consequences of this uncertainty has been a number of significant consolidations and mergers, and this trend has trickled down into the crushing industry. And while there have been some significant changes to this sector of the mining industry, many of the big players have weathered the storm. The following is a look at some of the mineral processing companies that will be at MINExpo. McLanahan Corp. McLanahan Corp. is an example of the changes in the sector. The crushing and grinding stalwart acquired Universal Engineering, expanding its traditional focus on soft mineral crushing to hard rock crushing. At MINExpo, it will be showing off three new pieces of equipment, the LabMill Crusher, the Rocker Tooth Crusher and the Recessed Filter Press.

Jan 1, 2012

By V. T. McLemore

New Mexico Bureau of Geology and Mineral Resources (NMBGMR) has been collecting data on uranium mining districts, mines and mills since it was created in 1927 and has converted years of historical data into a relational database that can be imported in ArcMap. The database includes information on mining districts, mines, mills and geochemistry, as well as photographs and bibliographic resources. The available data includes location, production, reserves, geologic, geochemical, resource potential and other data. The National Uranium Resource Evaluation (NURE) stream-sediment data provides geochemical analyses for >27,000 samples collected in New Mexico during the 1970s. The NURE hydrogeochemical data provides analyses of water samples. ArcMap includes the location of individual ore bodies as polygons and incorporates the mines and NURE data as individual site locations. The purposes of these databases are to provide computerized data that will aid in identifying and evaluating resource potential, resource development and management, production and possible environmental concerns, such as physical hazards (i.e., hazardous mine openings), indoor radon, regional exposure to radiation from the mines, background geochemical data and point sources of possible pollution in areas of known mineral deposits.

Jan 1, 2010

By M. Sunkpal, K. C. Kocsis

"An underground environment with high air temperature and humidity conditions generated from various heat and moisture sources can significantly affect the thermoregulation processes of the human body. This can lead to a series of heat-related illnesses such as heat exhaustion, heat cramps and heat stroke. The majority of the metabolic energy of a mine worker results in the production of heat. If the human body is to maintain thermal equilibrium, then this metabolic heat must be transferred to the ambient surroundings at the same rate. The heat loss from the human body occurs through a combination of heat transfer processes, such as respiratory heat exchange, convection, radiation and evaporation. If the heat loss from the human body to the ambient surroundings is less than the metabolic heat produced, the excess will be accumulated within the human body, which will result in a rise in the core and skin temperatures. This can ultimately lead to a heat-related illness or a combination of heat-related illnesses. This paper aims to discuss major heat-related issues and provide an overview of various mine ventilation and cooling systems, which can be employed to overcome high levels of heat and humidity in underground mines. In this paper, the effects of heat exposure on the health, safety and productivity of the mine workers are also highlighted. IntroductionMining in the United States remains one of the most hazardous industries, despite significant reductions in fatal injuries over the last century (Coleman and Kerkering, 2007; Saleh and Cummings 2011; Jacklitsch, Musolin and Kim, 2016). Occupational health hazards within the mining industry include hazards that are physical, such as traumatic injury or hearing loss; chemical, such as silica or diesel particulate matter; biological; ergonomic; and psychological (Donoghue, 2004; Saleh and Cummings, 2011). The effects of some of these hazards can be diagnosed immediately, while many, like black-lung and silicosis, will have long-term effects on the health, safety and life quality of mine workers (Donoghue, 2004; National Institute for Occupational Safety and Health, NIOSH, 2000). Among these hazards, exposure to heat and humidity can significantly affect the safety, health and productivity of mine workers, particularly in deep and hot underground mines (Roghanchi, Sunkpal and Kocsis, 2015). Short-term acute heat exposures can cause a rise in the core temperature of the human body, which can result in a heat-related illness or combination of heat-related illnesses. Adverse long-term chronic heat exposure can generate serious occupational heat-related illnesses, such as cardiovascular diseases, mental health problems and chronic kidney diseases. High core body temperatures coupled with dehydration can generate negative behavioral effects such as physical fatigue, irritability, lethargy, impaired judgment, loss of dexterity and loss of concentration (Xiang et al., 2014)"

Jan 9, 2017

By P. K. Sollars, M. A. Alspaugh

In May of 1996, Twentymile Coal Co. began Longwall mining in the Foidel Creek Mine's East Mine District. These Longwall panels are some of the longest in the world (5.48 km/18,000 ft) with very difficult and challenging geometry. The conveyance system is 1,800 mm (72 in) wide, has a 4,500 mtph (5,000 stph) capacity and employs multiple tripper drives. The trippers include traditional powering designs as well as unique regeneration and braking designs. Several components were developed specifically for this application including a mobile tail brake. Control algorithms were carefully developed and tested via computer modeling. A world production record was achieved in the third month of operation and over 1 million tons were mined in June 1997.

Jan 1, 1998

By Grant A. Brackebusch

Paste tailings disposal was successfully implemented at the New Jersey mill in Kellogg, ID with two different types of ore feed, a gold ore and a silver ore. The purpose of this paper is to describe the production of paste tailings, including operational problems during commissioning, and also highlight the environmental and economic benefits that were realized versus conventional tailings disposal such as the recycling of process water, increased shear strength and reduced permeability of the tailings mass, and reduced environmental permitting.

By Fernando Jorge Dick

Artificial sulphides have been produced on the surfaces of heavy metal-oxide, minerals at elevated temperatures (1) and these sulphides gave consistently similar flotation characteristics as the respective natural sulphides. In the case of tin, the only natural tin sulphide known is herzembergite (SnS) which is found only in minor quantities, and its flotation behavior is not known. Balberyszki, Dorenfeld, and Carmi reported (2) tests with artificial tin oxide and pure cassiterite treated with hydrogen sulphide at temperatures above 750oc. They confirmed that the product could be floated in acid pulps. However, iron sulphides derived from pyrite, limonite, and hematite which are generally the major impurities in tin bearing ores could not be separated from tin sulphides under the conditions used by previous investigators. As a practical matter, if complex tin ores or complex low grade tin concentrates are to be treated by this process, it is necessary to be able to separate sulphidized cassiterite from other sulphidized minerals in the feed. The major metallic minerals, by weight, in complex tin ores are the iron minerals--pyrite, hematite, limonite, magnetite and pyrrhotite. These minerals become (or remain) sulphidized during the sulphidization process.

Jan 1, 1978

By A. T. Yu

A recent analysis completed by the United States Department of Commerce predicts that the 1968 Gross National Product will reach a record high of 864 billion dollars. As our nation annually increases its total output of goods and services, as has been the trend, the consumption of steel and its most basic raw material - iron ore - also must increase, To deliver the most economical unit of iron ore to the blast furnace, each segment of the transportation system must be co-ordinated and utilized to its highest degree of efficiency. In some cases, such as with the water segment of the system, a new investment in capacity will be required.

Jan 1, 1968

By Mahiyar Nasarwanji, Jonathan K. Hrica, Jonisha P. Pollard, Lydia M. Kocher, Brianna M. Eiter

Within the metal/nonmetal mining sector, fall-related incidents account for a large proportion of fatal and nonfatal injuries that occur in mining in the United States. However, the events and contributing factors leading up to these incidents have not been fully investigated. To help provide a clearer picture of these factors, an analysis of imminent danger orders issued by the U.S. Mine Safety and Health Administration (MSHA) from 2010 through 2017 at both surface and underground metal/nonmetal mine sites revealed that most orders are associated with fall risks. Of these cases, 84 percent involved the workers not using fall protection, fall protection not being provided or the improper use of fall protection. Fall risks for workers most frequently occurred when standing on mobile equipment, performing maintenance and repairs on plant equipment or working near highwalls. In most cases, a single, basic, corrective action — such as using fall protection — would have allowed workers to perform the task safely. Overall, these findings suggest that a systematic approach is needed to identify, eliminate and prevent imminent danger situations. Furthermore, to protect mineworkers from falls from height, frequently performed tasks requiring fall protection should be redesigned to eliminate the reliance on personal fall protection.

By S. Todd Mickleborough

The geostatistical technique of conditional simulation is applied to measure the uncertainty in factor of safety predictions for soil slopes where there is incomplete knowledge of the spatial distribution of soil properties. A case study considers a natural clay slope in Canada. The sequential indicator simulation technique is used as a means for generating a series of spatial maps of soil properties for this site. These maps approximate random draws from the conditional probability density function that characterizes existing uncertainty in the spatial distribution. Factor of safety determinations are then made for each simulated map using the simplified-Janbu approach, where the computations are performed with a new computer program that can operate on irregular spatial profiles of soil properties specified on a discrete grid. A unique capability of this approach is the ability to generate the distribution of factor of safety conditional to the type, position, and value of existing site characterization measurements. This capability should reduce uncertainty in FS predictions.

Jan 1, 1993

By J. M. Mutmansky

A number of previous publications have attempted to provide the practicing ventilation engineer with simple guidelines on the optimal velocity to be used in mine openings. Some of these velocities were meant to be used in metal mining operations and some were meant for coal mining. A careful review of these publications reveals that the optimal velocities were determined based upon assumptions that are not existent today. As a result, they are not suitable for use in a modern coal mine. This paper takes a new look at this problem and determines a statistical relationship for optimal velocity that can be applied under both current and future conditions. The analysis performed here is based upon the determination of the optimal velocity for coal mine entries under variations in power cost, mining cost differential, airway friction factor, time value of money, airway lifespan, and quantity of air carried. A total of 8400 different conditions were analyzed for optimal velocity using computer calculation of the capital and operating cost values. Using the individual values of the optimal velocity derived in the calculations, a linear regression equation was fitted to the data to relate the optimal velocity to the other six variables outlined above. This regression relationship allows the ventilation engineer to make an easy, rapid determination of the optimal velocity.

Jan 1, 1984

By Y. J. Wang

A critical path approach is presented for the problem of mine ventilation net- works where regulators and fans are employed to control the airflow distribution which is preassigned. The problem is a classic one which arises in mine ventilation planning. By identifying the analogy between the network for controlled flow and that for CPPI, the applications of the well known CPM technique to the ventilation network problem become straight- forward. The mathematical formulation of the problem is presented and the solutions are illustrated with examples. The effect of booster fans on the total air power consumed in a ventilation network are also discussed.

Jan 1, 1981

By Barrie C. Butt

The opportunity for an exploration geologist to follow a successful exploration project through the feasibility, financing, construction, development and exploitation phase is rare. In addition, it is not often that the exploration geologist can be present during the mining of a deposit to explain why certain actions were taken or interpretations made and to find out how these interpretations turned out in actuality. At the Woodsreef chrysotile asbestos mine in New South Wales, Australia, mining has been in progress for six years and the writer has been intimately associated with the project during the five years of exploration and the six years of exploitation. The industry is possibly aware of the fact that the Woodsreef Mine has had major production problems, the majority of which have stemmed from the unique characteristics of the ore body and of the fibre. Because of these unique features, a large volume of research has been undertaken by Woodsreef and by other scientific organisations in Australia, England and Canada on the Woodsreef fibre. The answers to some of the problems have negated some semi-sacred concepts of asbestos ore milling and led to the development of new techniques, such as the adoption of microscopic fibre counts as a routine procedure; the modification of accepted evaluation procedures; the development of new machines for dedusting fibres, and to the recognition of a fibre with a unique milling behaviour pattern and, possibly, properties. The problems experienced can be divided broadly into those associated with the geology and those associated with the physical properties of the fibre. It is possible that the same features may manifest themselves in other deposits around the world, and if they can be recognised during the exploration stages a feasibility evaluation may be just that little closer to the actual.

Jan 1, 1978

By G. T. Lineberry

Horsepower requirement is recognized as a most important equipment characteristic. Other critical equipment characteristics will be isolated and analyzed by traditional operations research techniques, using off-highway trucks as an archetype. A computer search technique has been developed, employing various production and cost analyses. With this model, the optimum combination of horsepower, capacity, and velocity can be found, minimizing handling cost per ton. An example of the program's use and interpretation of its results will conclude the paper.

Jan 1, 1984