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By H. E. Wyslouzil

The highly competitive nature of the international iron ore market has forced producers to improve the quality of their pellets. The demand for low acid pellets suitable for direct reduction has resulted in an increase in the number of plants utilizing reverse froth flotation for silica reduction. Column flotation is being favoured for this service due to the low capital and operating cost of the equipment, as well as improved metallurgical performance when compared to conventional flotation cells. This paper describes the benefits of column flotation and discusses some important aspects of circuit design.

Jan 1, 1993

By J. Potter, A. Anani, C. Antonio

This research aims to test the hypothesis that the low retention rate of women in the mining industry is caused by workplace culture and policies established due to gender segregation. A quasi-experiment is developed to determine the cause-and-effect relationship between gender segregation-inspired culture and the retention of women. The experiment considers the impact of the job type and the operational environment. The analysis provides information on factors that cause low retention of women in the industry, the extent to which gender segregation plays a role, and insights that allow actionable and measurable changes in the industry.

Feb 1, 2023

By Ricardo Oliveira Gallart de Menezes, Claudio Gerheim Porto, Reiner Neumann

This study presents the results of the mineralogical characterization of Ti-Zr ore from the Jiboia deposit, located in the municipality of Brejo Grande, Sergipe State, Brazil. The goal is to identify the main Ti, Zr, and REE carrier phases in the different particle size fractions in order to subsidize the development of a cost-effective processing route for the production of heavy minerals concentrate. The mineral resources are estimated at 31.5Mt @ 3.5% of total heavy minerals (THM) for the Jiboia Ti-Zr deposit, of which 5 Mt @ 3.39% THM were classified as measured and indicated. The mineralogy of the heavy mineral concentrate recalculated to 100% is represented by 22% pseudorutile, 20% ilmenite, 15% zircon, 5% rutile, 2% monazite, and 36% gangue. The ore minerals are preferably concentrated in the 150 × 53-μm granulometric fractions, which represents 80% of the THM and only 27% of the ROM (Run-of-Mine) ore. Therefore, by cutting the ore to 150 μm, it is possible to discard 73% of the ROM mass and recover 80% of the THM, including 100% of the zircon and monazite which are the most valuable minerals present in the heavy mineral concentrate. The global recovery of THM starts to decline rapidly in the fractions finer than 106 μm and the mass disposal (tailing) does not follow in the same proportion. Higher zircon contents in the concentrates of the fractions finer than 150 μm imply a significantly lower recovery of heavy minerals like ilmenite, pseudorutile, and rutile that make the fractions coarser than 150 μm.

Jan 9, 2024

By Richard C. Corson

The objective of blending materials in a bedding pile is to reduce the variation in successive samples taken from the materials to be blended. In designing a bedding and reclaiming operation, several mechanisms are available to effect the reduction of variability, or increase in homogeneity, of the materials. These mechanisms can act before stacking, in the stacking process, in reclaiming and after reclaiming. In evaluating alternative methods of stacking and reclaiming, the potential user must judge each method on the basis of certain criteria; the capital cost of the equipment, the allowable absolute variability of the reclaimed product and the effectiveness of blending. Several stacking and reclaiming methods have been tested using a computer simulation. Based on the results of this program, factors were developed to describe the effectiveness of blending for chevron stacking of discrete materials and preblended materials, bucket wheel reclaiming and drum reclaiming. From these factors, the total effectiveness of a combined stacking and reclaiming system can be determined.

Jan 1, 1985

By Irwan Halim, Young Jin Park

A new tunnel lining was designed for rehabilitation of the existing unlined Weehawken Tunnel in New Jersey. Structural assessment using beam spring models was performed for the lining design as a drained structure at the invert with a waterproofing umbrella. Empirical Federal Highway Administration (FHWA) guideline was typically adopted for estimating hydrostatic pressure, which recommends full hydrostatic pressure at the crown and ten or twenty-five percent gradual reduction from the initial pressure toward the invert. Finite element seepage analyses were conducted for the actual conditions based on anticipated drainage behind the lining and impact on the structural design. Considerations will be provided on the existing guideline for estimating hydrostatic pressures.

Dec 1, 2022

By Siddhartha Roy, Hemant Agrawal, Ram Madhab Bhattacharjee, Devi Prasad Mishra

Heat stress is a major concern for the health, safety and productivity of miners working in hot and humid underground mines. At greater depth, heat inside underground mines increases due to geothermal gradient, heat released from high-capacity machinery, exposed rock surface, auto-compression of air, human metabolism, etc. Prolonged physical work in thermal environments severely affects the health, safety and efficiency of miners. In order to address this important issue, a systematic literature review (SLR) has been conducted. This SLR aimed to identify the research gap in the area of heat stress effect on underground miners and its control. An extensive literature search was carried out on numerous digital databases, grey literature and conference proceedings to identify relevant research work for this review. Moreover, the impactful studies, methodologies and preventive measures undertaken during the past five decades on the effect of heat stress on underground miners were retrospectively analysed, with a broader aim to explore the need for further research on this pertinent topic. Overall, 571 references were identified from the literature review, out of which 51 research articles addressing the sources of heat, heat stress effects on miners, heat stress indices and control measures for heat stress in underground mines were selected as primary papers for detailed review. Pre-developed fatigue is one of the prime causes of health hazard, safety and productivity loss of miners working in underground high heat stress zones. Hence, development of a better heat stress index integrating personal, environmental parameters and pre-developed fatigue (PDF) of miners is essential.

Jan 14, 2022

By Yushuai Xian, Youjun Tao, Fangyuan Ma

This study compared particle size distribution and density distribution of crushed products for waste printed circuit boards (WPCBs) before and after heat treatment. The crushing process for heat-treated WPCBs is a selective crushing process; more metal is concentrated in the coarse particle range of 1.0–0.5 mm and high density range of 2.8–2.96 g/cm3. WPCBs were separated using the Falcon separator to recycle useful metals. The Box-Behnken module of Design-Expert was used to obtain optimal separation parameters, namely, rotational frequency of 25 Hz, recoil water pressure of 0.025 Mpa and feed speed of 34 ml/s. On this basis, the separation indexes for WPCBs with and without heat treatment were compared. Experimental results show that the recovery effect is better for heat-treatedWPCBs than for thosewithout heat treatment. Comparedwith the non-heattreatedWPCBs, the product grade of heat-treated WPCBs is 1.95% higher, and its recovery is improved by about 14%. Finally, characteristics ofWPCBs before and after heat treatment were analyzed on the basis of stress experiments and scanning electron microscopy (SEM), respectively. Results of mechanical characterization indicate that the stress experiment for non-heat-treated WPCBs has a maximumpressure load of 212 N and displacement of 20mm, but heat-treatedWPCBs only need 140 N stress and 14 mm displacement. SEM shows that copper foil and fiberglass cloth are deformed in different directions and sizes after heat treatment to form gaps, which promote liberation of copper foil and fiberglass cloth.

Sep 10, 2020

By AMIT SHARMA, BIBHUTI BHUSAN MANDAL

Operators of mining vehicles are exposed to high levels of whole-body vibration (WBV) and are therefore at risk of developing vibration-related health disorders. For implementing an effective control strategy, it is imperative to locate the source(s) of vibration, and the specific changes that might occur to the vibration signals during its transmission through the seats to the recipient human body. With this objective, Seat Effective Amplitude Transmissibility (SEAT) values of seat modules used in dumpers (n = 10) and other heavy earth-moving machines (n = 11) were evaluated in an iron ore mine. Vibration was measured simultaneously on the seat and on the cabin floor beneath the seat using tri-axial and uni-axial accelerometers. The study aims at determining the quality of seat modules of the transport and non-transport vehicles from the perspective of their natural resonance frequencies and capability of any such seat in reducing harmful vibration. The highest acceleration values were observed in the z-axis for all the dumpers. SEATrms values ranged from 78 to 133% and SEATvdv values ranged from 72 to 130% for the dumpers. For other HEMMs, SEATrms values ranged from 55 to 125% and SEATvdv values ranged from 56 to 123%. Mechanical vibration contains multiple frequency components. To understand the changes taking place to the different signals at these frequencies, 1/3 octave band analysis was carried out for the signals recorded both on the seat and the floor. There was significant attenuation (38 to 57%) at 4 Hz for three Dumper seats, whereas they resonated in the range of 1.6–2.5 Hz. The transmissibility(%) in the resonating frequencies ranged from 108 to 156%. Resonance frequencies for the remaining seven dumpers ranged from 3 to 8 Hz. The spine has been reported to resonate at 4 Hz, whereas resonance at 1.6 Hz has little significance to human beings in regard to WBV of a seated person. Hence, the characteristic resonant frequency of 4 Hz of seats as observed in the present study has the potential of causing adverse impacts on spinal health. Evaluation of SEAT factors and resonance characteristics of seats are therefore recommended to be examined while selecting a mining vehicle for regular deployment in mines.

Mar 12, 2021

By P. Somasundaran, S. Venkatachalam, N. K. Khosla, K. Khosla

Froth flotation of alumina particles was studied by employing and hydrogen gas bubbles. The effect of current density was studied over a range of 0.1 to1.6 kA/m2. Compared to hydrogen, the use of oxygen bubbles at any given gas evolution rate resulted in a higher flotation recovery. The existence of an optimum current density, for each given particle size was indicated. Flotation at higher current densities resulted in better flotation kinetics, while flotation at lower current densities resulted in better Spas utilization.

Jan 1, 1996

From a gathering storm of climate change based legislation that could potentially overwhelm the mining industry, to the nuts and bolts of mineral processing and just about everything in between, about 100 mining and mineral processing professionals heard it at all at the 60th annual Colorado MPD Meeting April 22-24 at the Broadmoor in Colorado Springs, CO. With a sweeping agenda under the banner ?What in the world is new in mining and metallurgy? attendees were treated to four sessions and 21 presentations that covered the range of mining industry issues. Bill Reid, president, chief executive officer and director of Gold Resources Corp., spoke about his company?s El Aquila gold project in Mexico. With five projects in Mexico, Gold Resources Corps. is aiming to become a low-cost gold and silver producer. Its flagship property, the El Aguila gold project, is a high-grade gold and silver property with significant base metal credits of copper, lead and zinc. Production of the El Aguila project was targeted for mid-2009. Reid said that three high-grade deposits have been discovered at the El Aguila project. They include the high-grade ?manto? style El Aguila openpit deposit, the El Aire high-grade polyme-tallic vein system, which is underground, and the underground La Arista high-grade polymetallic vein system. The project is located 120 km (75 miles) south-east of the capital city of Oaxaca, Mexico. Reid said the property has yielded several exceptional gold and silver surface samples, including a 36-g/t (1.1 oz/st) gold sample and a 3,100-g/t (90 oz/st) silver sample. Other properties that Gold Resource Corp. has are:

Jul 1, 2010

By C. L. Lin

The image-based On-line Particle Size Analyzer (OPSA) system has been developed at the University of Utah to measure particle size distributions under plant conditions where overlapped and segregated particles are being transported on a moving belt conveyor. Evaluation of the OPSA system at several plant sites has been completed. The results show a consistent agreement between the particle size distributions obtained from the OPSA system and those obtained from laboratory screen analysis of belt samples. These results and the stable performance of the OPSA system during the field tests suggest that continuous quality control of crushed products is possible using the OPSA system.

Jan 1, 1999

By James S. Goff, Stephen J. Navin, Wesley W. Moulton

The White River Shale Oil Corporation (WRSOC), as agent for Phillips Petroleum Company, Sohio Shale Oil Company, and Sun Shale Oil Company, is developing a prototype oil shale facility on Federal Lease Tracts Ua and Ub, located in northeastern Utah and known as the White River Shale Project (WRSP). The Ralph M. Parsons Company (Parsons) has been retained as the design engineer/constructor for the project. This paper covers the successful pregrouting of the Bird's Nest Aquifer in conjunction with the sinking of a 9.2-m (30-ft)-diameter shaft and driving of a 3.89-m by 5.64-m (18.5-ft by 12.75-ft) decline. The Bird's Nest Aquifer derives its name from the ellipsidal solution cavities caused by leaching of random-size nacholite nodules. The sodium bicarbonate nodules occur as persistent bands within a matrix of siltstone and marlstone. The team, made up of the owner, engineer/contractor, and subcontractor successfully grouted the shaft down to an inflow of less than 0.06 lps (1 gmp) and the decline down to less than 0.12 lps (2 gpm) by injecting a total of 213.190 kg (470,000 lb) of Celtite Terraseal, 113,400 kg (250,000 lb) of limestone dust, and 41,730 kg (92,000 lb) of cement into the formation.

Jan 1, 1985

By Shakuntala Tudu, Indrajit Paul, Surajit Sinha, Pulibandla Basaveswara Rao, Shaik Mahaboob Basha, Srinivas Dwarapudi

The iron and steel manufacturing sector directly accounts for 7–9% of global CO2 emissions. Raw material preparation, such as iron ore sintering, pelletizing, and cock making, is the major CO2 emitter. As climate change becomes a bigger concern, steel manufacturers need to lower CO2 emissions without hindering efficiency or increasing costs. In recent years, the percentage of iron ore pellets in blast furnaces has increased due to its uniform size, good reducibility, and high tumbler index. Pelletizing is energy-intensive and emits considerable CO2. Around 20% of CO2 emissions during pellet making come from fluxes. In the present work, the authors established a novel CO2- free flux called wollastonite (CaO.SiO2) for sustainable palletization. Pellets with varying percentages of wollastonite (0–6%) are prepared and tested for chemical, physical, and metallurgical properties. Image analysis through an optical microscope is carried out to quantify the phases of fired pellets. SEM–EDS is performed to evaluate the chemical composition of the melt and slag phases. The results showed that the reducibility index (RI) and swelling index (SI) of pellets decreased with an increase in wollastonite dosage. Pellet strength increases with an increase in wollastonite addition up to 1.2% CaO (2.27% wollastonite), and a decrease in strength is observed thereafter. The increase in strength is attributed to the increase in slag bonds. The decrease in strength beyond 1.2% CaO is mainly because of an increase in low melting eutectics and more magnetite content. Pellets with 2.27% wollastonite to get 1.2% CaO showed good physical and metallurgical properties.

Mar 4, 2024

By J. R. Batista

Leachates from gold heap-leaching mines contain selenium concentrations as high as 2 mg/L. Previous studies report satisfactory selenium adsorption by activated alumina when using relatively "clean" drinking waters. However, the findings of these studies cannot be directly applied to the treatment of mine leachate where other ions compete for the alumina adsorption sites. This study evaluated the adsorption of selenium from a mine leachate to develop design parameters for full-scale activated alumina processes. The study revealed that 68% of the selenium in the leachate could be removed by alumina at pH > 5.0. Silica adversely affected the selenium adsorption capacity. At pH values < 4, silica was poorly adsorbed by alumina and selenium adsorption was improved.

Jan 1, 1994

By Tuanhui Wang, Qiwei Wang, Quanrui Liu, Jianhui Xu, Chao Wang, Yu Liu, Yuefeng Li

Rockburst is a highly destructive geological hazard that can cause casualties and equipment damage. To achieve highaccuracy discrimination of rockburst intensity, this article proposes an improved model that addresses the inefficient maximum membership principle used in traditional rockburst fuzzy evaluation models. The stress coefficient σθ/σc, brittleness coefficient σc/σt, and elastic deformation energy index Wet are selected as evaluation indicators for rockburst classification. Subjective and objective weights are obtained using the Delphi method and entropy weight method (EWM). Three types of membership function distribution forms are then used to obtain the membership degrees of each indicator to rockburst grades: trapezoidal membership function (TMF), normal membership function (NMF), and quadratic parabolic membership function (QPMF). Finally, six traditional models and six improved models are established using the maximum membership principle (MMP) and weighted average-maximum membership principle combination evaluation principle (WMP), respectively. Based on the analysis of 100 sets of rockburst field data, the accuracy, precision, recall, and F1-score of the improved evaluation model are increased by 11.3%, 0.097, 0.068, and 0.089, respectively, compared to the traditional model. The Delphi-NMF-WMP model is selected as the best model, with four performance indices reaching 97.0%, 0.979, 0.979, and 0.978. The best model is applied to evaluate the rockburst intensity of the Cangling Tunnel, Dongguashan Copper Mine, and Jiangbian Hydropower Station Diversion Tunnel, with evaluation results consistent with the actual situation, demonstrating the reliability and scientificity of the model.

Feb 28, 2024

By Henrique D. G Turrer, Desmond Edifor, Marcello R. Cruz, Josue M. de S Junior, Darius Wonyen

A geometallurgical testing program was developed to anticipate ore behavior in the beneficiation plant and support production planning. Over 100 drill core samples from a major iron ore deposit were tested using bench-scale gravity and magnetic separation methods to assess variability in process responses. Results showed significant differences in key attributes such as iron grade, gangue content, slimes generation, and specific gravity, directly impacting concentrate grade, recoveries, and tailings quality. Correlation analysis and regression models were used to link feed properties to process outcomes, and a mass recovery estimation equation (Wrec) was developed for predictive use. The study proposes the integration of geometallurgical parameters—such as Fe, SiO2, Al2O3, LOI, ore type, size fractions, and slimes content—into the block model to support blending decisions and minimize operational risks. This work establishes a solid foundation for long-term mine-to-plant integration, with future phases aiming to expand testing and build a calibrated geometallurgical model.

Feb 22, 2026

By J. D. Grenia

The Buick Mine is a joint venture of American Metals Climax, Inc., and Homestake Mining Company located 120 miles by road southwest of St. Louis, near the village of Boss, in the &apos;New Missouri Lead Belt&apos; (See Figure 1). Since start-up in 1969, over four million tons of lead-zinc ore have been mined and milled at Buick. Situated about 1,100 feet below the surface at an elevation 270 feet above sea level, the flat lying sinuous ore bodies are up to 250 feet wide, 85 feet high and several thousand feet long. Mineralization is galena, sphalerite and chalcopyrite in dolomite, Access to the mine is through two 18&apos;Ø concrete lined vertical shafts - one for servicing and the other for hoisting ore (See Figure 2). The mine is being worked by a modified room and pillar method using both rubber tired equipment and a sub-level rail haulage. Ore is broken from first pass headings, back and bench faces and transported by load-haul-dump units to ore passes located on 900 foot centers. The ore is pulled from chutes on the sublevel 90 feet below into 15 ton bottom dump cars and delivered in 10 car lots by a 15 ton diesel locomotive to a 42" gyratory crusher (See Figure 3). A recent innovation has been the introduction of two 50 ton trucks with plans to haul up to 60% of the ore on the mining level to an ore pass feeding directly to the primary crusher (See Figure 4). Ventilation raises up to 16&apos;Ø, which were originally planned for 900 foot centers, are now driven on 450 foot centers.

Jan 1, 1973

By Alan A. Campoli

The US Bureau of Mines (USBM) conducted research to develop improved guidelines for selecting the type and pattern of roof support in different geologic environments. The goal is to minimize the over and under design of mine roof support, resulting in more productive and safer mines. To obtain the necessary data on roof behavior and support performance, USBM conducted several field studies. Each study covers roof geology, stress regime, ground reaction, support interaction and mining environment. A consistent experimental design is being used. This includes measurements of roof bolt loads and roof movements. So far, 10 studies have been conducted in several geologic settings.

Jan 1, 1996

By M. J. Shulman

An algorithm used by the US Coast Guard to find lost objects is utilized to optimally allocate exploration efforts during initial stages of an exploration program. Based on classical search theory, the algorithm assumes a target probability distribution function, a detection func¬tion, and a cost function. The three Junctions are analogous to delineating areas of possible mineralization, choice of exploration methods, and exploration budget. Application of the algorithm is shown for a hypothetical target distribution. Using the maximum number of field days available as the cost function, the optimal allocation of effort is shown for different exploration methods, e.g. electromagnetic survey and induced polarization. The adaption of the algorithm for the exploration process is discussed.

Jan 3, 1984

By Immo H. Redeker, O. E. Pothier, E. W. Gieseke

Phosphate rock is the primary source of phosphorus, an element necessary to all forms of life--plant, animal, and human. While phosphorus finds many uses in everyday life, it is an irreplaceable ingredient in all complete plant foods. With the present need for intensive farming, the fertility of the soil can be maintained only by external additions supplied by mines or other sources. A major consideration in any mining operation is to establish the economic and ecological impact of the development on the local population as well as the national interest. The Commodity Data Summaries, as published by the U.S. Bureau of Mines (USBM), is a ready reference concerning the importance of phosphate to the national and local interest. The summary of domestic and world pro¬duction is given in Table 1. During 19722 the demand for marketable phosphate rock exceeded the supply in the United States and the rest of the world. Domestic and world reserves are more than adequate to meet furture demands. Phosphate rock prices firmed and export prices increased, reflecting the change from oversupply to a shortage of phosphatic fertilizers. Demand is expected to exceed supply through 1973. New fertilizer plant capacity planned for 1973-74 will increase the production of phosphate rock by more than 5 million tons in the United States. Morocco and Spanish Sahara are scheduled to increase their production to 18 and 3 million tpy, respectively, within 2 to 3 years. The domestic phosphate rock production for 1972 was 40.8 million tons and 1973 was 42.1 million tons.&apos; Industry, with government-supported programs, will emphasize restoration of mined land and solution of the colloidal slime disposal problem in Florida. The foregoing information comes by courtesy of The Division of Nonmetallic Minerals of the U.S. Bureau of Mines, January 1973. The summary gives a great deal of information but does not give a complete picture. There are many supporting industries which contrib¬ute to the area in which the mines are located. The figures shown in Table 1 deal with concentrates. To produce such concentrates many more tons of waste overburden and ore must be moved. Because of the competitive nature of the phosphate rock industry, data on concentration ratios not only are difficult to obtain but also are not for publication by companies. The concentration ratios vary from one mine to the next in Florida as well as in Tennessee and the western United States. To produce 42.4 million tons of phos¬phate rock in the United States required moving about 350 to 400 million tons of material. Domestic Industry. In 1972 some 26 firms and the Tennessee Valley Authority produced phosphate rock, with several firms produc¬ing from more than one mine. The distribution of marketable phos¬phate rock production was: Florida and North Carolina 82%; Idaho, Montana, Utah, and Wyoming 13%; and Missouri and Tennessee 5%. The value of this production was $223 million. The principal consuming classifications were: agriculture 75%, soaps and detergents 5%, plating and polishing 3%, animal feed supplements 4%, and miscellaneous applications 13%. Over 5,000 firms processed end-prod¬ucts for agricultural purposes. Uses of Phosphate Rock. The tendency in the United States has been to produce more phosphoric acid by the wet process, while the production of electric furnace phosphorus, triple superphosphate, and ordinary superphosphate has been on the decline. Exports of phosphate rock have been on the increase for several years and in 1971 reached 33% of total production. However, export sales of phos¬phate rock are expected to decline in the years ahead, both in total tons of sales and in percentage of production as domestic sales increase (see Table 2). The description and chemistry involved in the production of phos¬phate fertilizers is too complicated to be presented here. The Waggaman13 book is a very thorough reference on the subject involv¬ing production, utilization, and chemistry. The various operations generally have chemical plants near the dry plants or ship to associated chemical plants for further processing. Wet rock, dry rock, and ground dry rock of various grades are sold. In addition various grades of calcined phosphate rock, including defluorinated phosphate rock for animal food supplements, are pro¬duced. Various grades of phosphoric acid, superphosphate, triple suerphosphate, as well as diammonium phosphate, are produced. These products are available from the various producing compa¬nies listed in the text. For prices and specifications the producing companies should be contacted.

Jan 1, 1985