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By P. G. Rueffel

"Natural deposits of sodium sulphate are the result of normal geological processes. They are world-wide in occurrence and are found in depressions in arid and semi-arid regions. Primarily, the sodium sulphate deposits of the prairies are post-glacial and differ from rock salt deposits, which originated from connate water (fossil sea-water). Sodium sulphate on the Canadian prairies occurs as brine or in beds of intermittent and/or permanent crystals. Most beds are contaminated with various amounts of silt, sand and decayed organic matter. Soluble impurities such as chlorides, carbonates and bicarbonates of sodium and sulphates of magnesium and calcium are leached out from the soil of the surrounding run-off area of the deposits.In this paper, the origin of sodium sulphate, and the physical and chemical aspects related to the development of the Ingebrigt Lake deposit are dealt with. The problems of garnering raw material, and of refining and de-hydration are discussed, with emphasis on the Ingebrigt Lake plant. The utilization of the ""Total Power Concept"" in a sodium sulphate plant is described. The principal uses of sodium sulphate are also discussed."

Jan 1, 1968

By John J. Baz-Dresch

Catalyzed diesel particulate filters (CDPF's) reduce the concentration of diesel particulate matter (DPM) and may reduce the emissions of carbon monoxide (CO) and hydrocarbons (HC) in diesel exhaust. Asamera Minerals' Cannon Mine first installed CDPF's in 1987, and currently has 12 diesel-powered vehicles equipped with CDPF's. The Cannon Mine and the U.S. Bureau of Mines collaborated to evaluate the durability and performance of a CDPF. One of the CDPF's used at the mine was periodically evaluated in the USBM's diesel emissions laboratory after 839, 1,584, and 2,881 h of in-mine service. The objectives of this report are to present results from the USBM's evaluation of this CDPF, to describe the Cannon Mine's experience and cost analysis of using CDPF's, and to make recommendations for the future use of CDPF's. CDPF's improve air quality at the Cannon Mine, but they frequently become plugged and are subject to excessive mechanical shocks and stress, shortening their useful life. Mine records indicate that CDPF's account for 0.8 to 4.9 pct of the vehicles' operating cost at the lVine. CDPF life to date has ranged from 1,671 h to more than 5,992 h. Laboratory tests of the CDPF determined that DPM removal efficiency decreased and regeneration temperature increased over time.

Jan 1, 2010

By D. A. Beattie

Three novel dextrin polymers of varying functional group chemistry but similar molecular weight have been used to depress talc in single and mixed mineral studies. The mixed mineral system was a model sulphide ore consisting of talc, pentlandite, and chalcopyrite. Adsorption isotherms for the three polymers on both valuable and gangue mineral phases were determined to give initial clues as to the ability of the polymers to depress talc. Flotation testing revealed a distinct hierarchy of effectiveness of the polymers in the depression of talc in the single mineral system (MP Dextrin > CM Dextrin > Dextrin TYM), reflecting the observed adsorption affinity and adsorbed amount of the polymers on talc. However, a different order of effectiveness was observed for talc depression in the mixed mineral system (CM Dextrin > MP Dextrin > Dextrin TYM). Competition between the valuable and gangue mineral phases for uptake of MP Dextrin is responsible for its observed decrease in efficiency in mixed mineral flotation. All three polymers were found to be reasonably selective in their action, although at high dosages the polymers began to affect the flotation of the valuable minerals.

Jan 1, 2006

By J. B. Zadra

After the discovery of the rare-earth mineral deposit in the Clark Mountain area near Mountain Pass, San Bernardino County, Calif., two samples wore obtained through the Mining Division of the Bureau of Mines for investigation of possible method of concentration. Three other samples were received later from different locations in the same area. The rare-earth mineral in this ore had been identified by E. T. Schonk as bastnaesite, a fluocarbonate of the rare-earth metals containing cerium, lanthanum, praseodymium, thorium, uranium, etc. Associated with the bastnaesite were barite, silica, and some calcite. The bastnaesite contained a small amount of iron as a coloration and some manganese. Twenty to fifty percent of the weight of the samples studied was bastnaesite, or ten to twenty-five percent total rare-earth oxides; about half was cerium oxide. Apparently, none of this mineral occurred in pure form. Even the highest-grade particles 'wore contaminated by fine, interlocked grains of barite, calcite, and silica; barite contamination predominated, and the barite was interlocked with varying amounts of bastnaesite. While the specific gravities of pure bastnaesite and barite (approximately 5.0 and 4.50 respectively) differ enough to allow separation by gravity, the interlocking of the minerals nullified this difference. Consequently, only a partial separation could be made by gravity concentration. The extremely fine grained texture of most of the ore prevented grinding to a size that would make concentration by flotation practicable; a partial separation of barite by this means was effected.

Jan 1, 1952

By A. L. Hornbaker

Colorado has recorded more than 100 years of industrial mineral production. Much of the state's history, culture, and economy is based in mining, but the industrial minerals and construction materials comprising the nonmetallics sector of the industry very often are overlooked or overshadowed by mineral fuels and the metals. Indeed, many of these materials find use in seemingly unimportant industrial applications essential to our economy and life style and yet are not so recognized by the consumer. Unlike many other mineral resources, the numerous industrial minerals occur in many different and often exotic geologic environments, some of which are characteristic only of the western states. In Colorado only a few of these minerals have continued production through the years; many saw only "boom" periods or other critical times of need, such as the world wars. The changing needs and demands of our society in the 1980s will stimulate yet another era of intensive activity in our industrial minerals storehouse. Researchers are finding new uses and applications for these materials in dealing with the energy crisis and fuel shortages, the need to develop domestic mineral reserves of all kinds, and the goals of reuse and recycling. Some of Colorado's little-used and unused industrial minerals hold extraordinary promise in solving some of these problems on the regional and national levels. In this paper we will look at the history of development of Colorado's more prominent nonmetallics and especially at current research on and future potential of several other commodities among which Colorado contains the largest known reserves.

Jan 1, 1980

By J. S. WARWICK, E. J. Browning

Ignitions continue to occur underground, sometimes leading to major explosions. There has been considerable effort in the UK, and more widely in the European Community, to formulate the best ventilation practices and other means of minimising these incidents. Practices and procedures to prevent ignitions are discussed in the light of the risks from current mining methods.

Jan 1, 1993

By Yi Luo, Jian Yang

Subsurface strata movements and deformations associated with longwall mining operations in underground coal mines could cause various disturbances to subsurface mine structures, ground water bodies, and coalbed methane reservoirs. In order to assess those disturbances correctly and to design effective and efficient mitigation measures, it is necessary to develop an accurate prediction model for subsurface strata movements and deformations. Decades of research have demonstrated that variations of stratification and lithology in the overburden have significant influence on the subsurface strata movements and deformations during ground subsidence process. The key strata theory states that the thick and hard key strata serve as the backbone of the overburden and control the movements of the thin and soft weak strata located above them. From an engineering standpoint, the overburden strata are subdivided into several individual groups by the key strata with each group consisting of a key layer at the bottom and weak layers overlying it. A new subsurface subsidence prediction model considering the key strata effects on subsurface strata movements and deformations has been proposed. In this method, elastic modulus, specific weight, tensile strength, and uniaxial compressive strength (UCS) of each layer are used to identify the key layers and to determine the needed subsurface subsidence parameters. The influence function method, proven to be accurate and versatile for surface subsidence prediction, was employed to predict the subsidence on each of the overburden layers from mining horizon progressively upward to ground surface with the assumption that the predicted subsidence on a given layer serves as the subsidence source for the layer immediately above. The enhanced subsurface subsidence prediction model has been demonstrated with an actual case to show its applicability and improvement.

Jan 25, 2021

By S. Lohmeier, D. Gallhofer, B. G. Lottermoser, T. Schirmer

At a time of resource consumption, it is important to study the chemical composition of mining and metallurgical wastes to prevent the dissipative loss of metals and metalloids from the mining value chain. In particular, the recovery of critical elements from wastes is an option to increase the resources of such materials that are economically significant and have an overall supply risk. In this paper we report on the chemical composition, in particular the critical element content, of granulated slag originating from historical smelting activities in the Tsumeb area, Namibia. Laboratory-based inductively coupled plasma–mass spectrometry (ICP-MS) and X-ray fluorescence (XRF) analyses as well as portable X-ray fluorescence (pXRF) demonstrate that the slags are on average enriched in base metals (Cu 0.7 wt%, Pb 2.7 wt%, Zn 4.7 wt%), trace metals and metalloids (Cd approx. 50 mg/kg, Mo approx. 910 mg/kg) as well as critical elements (As approx. 6300 mg/kg, Bi approx. 3 mg/kg, Co approx. 200 mg/kg, Ga approx. 100 mg/kg, In approx. 9 mg/kg, Sb approx. 470 mg/kg). While metals and metalloids such as As, Mo and Pb can be determined reliably using pXRF instruments, the technique has inherent limitations in evaluating the contents of certain critical elements (Ga, Sb). However, there are positive correlations between the As, Mo, and Pb contents determined by pXRF and the Ga and Sb contents obtained through ICP-MS and XRF. Thus, quantitative pXRF analysis for As, Mo, and Pb allows calculation of Ga and Sb abundances in the slags. This work demonstrates that pXRF analysers are a valuable tool to screen smelting slags for their chemical composition and to predict the likely contents of critical elements.

Mar 1, 2021

In October 1993 it was decided to undertake the fourth phase of mining at Big Bell. This decision followed the exhaustion of open pit reserves in January 1993. Two stages of mining were proposed for the new underground mine. The initial stage would mine the remnant ore, consisting of the rib and crown pillars and lower grade ore on the hangingwall and footwall side of the old open stopes, which were mined from the 1930s to 1950s. Most of the old open stopes were backfilled with either deslimed mill tailings or development mullock, both of which were economic to recover. However, the mineable ore from this resource was difficult to evaluate. The second stage focused on mining ore outside the remnant areas and was initially proposed as a Core and Shell method under a caving hangingwall. This method has since been superseded with sublevel caving, in part due to the very high and deviatoric stress conditions encountered at Big Bell and the relatively long mining cycle required for open stoping. The problems and challenges discussed in this paper will cover the identification of remnant ore reserves, dewatering the old workings, and remnant mining.

Jan 1, 1998

By Changwoo Lee, Jan M. Mutmansky

"This paper results from the research at The Pennsylvania State University into establishment of standard procedures for characterization of respirable coal dust performed by the Generic Mineral Technology Center for Respirable Dust and supported by the U.S. Bureau of Mines and the Mining and Mineral Resources Research Institute at The Pennsylvania State University. The research performed within this particular project is oriented primarily toward standard methods of sampling and characterizing respirable coal mine dust underground so that the chemical, physical, and morphological characteristics are known and can be related to the incidence of coal workers' pneumoconiosis (CWP) in Pennsylvania.The research was initiated by con¬ducting a search of the literature to determine what coal and geologic variables may be related to CWP. The effects of coal rank, free silica content, the mass of respirable dust, and the level of trace elements were the major variables studied. It seems to be evident that the free silica content, the rank of coal, and the mass of respirable dust are the major concerns in defining the causes of CWP. However, based on the literature survey, the authors have concluded that verification of the causes of CWP is a multivariate problem and must be analyzed in an appropriate statistical manner.The results of a multivariate analysis of ten trace elements recorded on Pennsylvania coals are presented. Five of these trace elements were found to be of use in differentiating one coalfield from the others. Of these five elements, chromium and zirconium showed a strong positive correlation with the rank of coal while strontium showed a negative correlation.The design of the field sampling work and its application in future research is the final topic discussed. The sampling plan is oriented toward continuous miner sections with eight-stage impactors as the collection equipment. All of the field work will be conducted in the coal measures of the Allegheny Formation and above with both dust and channel samples being collected in the same mines.Coal workers' pneumoconiosis has been an important topic of concern to miners, mining engineers, and epidemiologists for decades. The general cause of the dis¬ease, the inhalation of coal mine dust, is well known, but the specific coal and geologic variables that affect the incidence and severity of the disease are still subject to debate and study. The primary objective of this study is to identify those variables of Pennsylvania coals that contribute to the CWP problem. To accomplish this task, a field sampling program is to be conducted to relate the characteristics of the coal dust, the coal seam properties, and the geologic variables to the occurrence of CWP.The first year of this study has been involved with both a literature review and experimental work oriented toward identification of causal variables related to CWP. The results of this work are presented here along with plans for implementation of the findings in future research.The previous studies of CWP causal variables have been conducted by scientists, engineers, and medical personnel. Many different types of studies have been performed with emphasis on interpreting the effects of dust mass concentration, mineralogy of the coal, the rank of the coal, and trace element concentrations upon the incidence of CWP in various coalfields. Most of the research has been conducted during the last two decades, with the British Isles, West Germany, and the United States being the primary countries involved.The review of the literature was conducted to determine which variables are likely to warrant further study in Pennsylvania. Previous research studies have related CWP to free silica and other mineral content, the rank of coal, the mass of dust in the working place, and the trace elements in the coal and lung dust. In the following sections, each of these topics will be discussed and analyzed."

Jan 1, 1988

By K. Robinson

Following the longest Smelter campaign in BCL?s history it was planned to completely rebuild the flash smelting furnace in 1987. This was the fourth major overhaul and the most extensive so far attempted. Detailed planning took place over several year$ preceding the shutdown and implementation was completed in 54 days. The key to minimising shutdown time was the method designed for installation of the new uptake shaft and reaction shaft. Major repair work was also undertaken in the waste heat boiler and electric furnaces. Both of these activities had an impact on the critical path of the flash smelting furnace overhaul.

Jan 1, 1993

By G Senanayake, K Hazarika

The demand for iron-ore is ever increasing with the industry directly employing 60 500 people in a range of highly skilled roles in Australia. In the year 2019, the global iron-ore production was 2.85 billion tonnes. It is estimated that each tonne of beneficiated iron ore produces 400 kg of tailings. The IOTs are fine, dense and stable crystalline material mainly composed of iron oxides, alumina and silica. The current and most applied method of iron-ore tailings (IOTs) disposal is using subaqueous disposal of tailings in dams. The footprint generated by a tailings dam is massive and requires constant monitoring due to the possibility of a failure making the operation and maintenance of tailings dam extremely expensive. This review briefly discusses the known causes of tailings dam failures, their impact to the environment and day-to-day human life and potential applications of IOTs. The increase in water content enhances the pressure on dam walls. This in turn increases the liquefaction potential of the tailings and reduces the overall strength of the dam making it more vulnerable to failure. Potential applications of IOTs are in paints, aggregates in construction materials and bricks. The reuse of IOTs reduce waste and generates further revenue facilitating a path towards a sustainable future for the industry.

Nov 8, 2021

By Oluwafemi Salami

Conducting full-scale fire experiments in underground mines is difficult and expensive. Sometimes, it is impossible to carry out fire tests in mines due to the danger they pose to mine workers and the underground facilities. However, understanding the potential occurrence of fires in a mine and their dynamics is critical to developing an appropriate emergency evacuation plan, fire suppression, and firefighting techniques. In this study, a numerical fire model using computational fluid dynamics (CFD) with fire dynamics simulator (FDS) 6.7.6 was developed to examine the influence of tunnel bifurcation on maximum temperature beneath a tunnel ceiling. The model was validated using full-scale experimental data. The maximum ceiling gas temperature predicted using FDS and measured maximum smoke temperature during the experiment shows good agreement. The study shows that bifurcation could lower the maximum ceiling temperature of fire-induced smoke in a subsurface environment. The findings from this study apply to the broader field of ventilation and fire life safety in tunnels and other underground environments.

Jun 23, 2024

By Aijuan Zhang, Liang Zhao, Yutao Wang, Yu Bao

In the green backfilling mining of underground coal mines, gangue in a coal seam is used to replace and fill goafs. However, the gas drainage time changes in the amount of gangue output and order in the extraction sequence of stope blocks, thereby changing the production output. A multi-objective integer programming model was proposed to solve this based on an improved non-dominated sorting genetic algorithm. The results show a feasible gangue filling rate can be found and the extraction sequence for a long-term planning time is optimized. It increases the planned annual output by 26% and reduces equipment idle time.

May 23, 2022

By A. Nieto

This article is a review of previous discussions about underground mining method selection and classification with the purpose to clearly define and classify the two groups of variables (indicators) involved in the mining selection process: key deposit indicators (KDIs) and key mining method indicators (KMIs). This paper provides a simple and clear approach for the classification and selection of a feasible underground mining method based on a predetermined set of favorable deposit characteristics, which are defined as key deposit indictors (KDIs). This article also gives a summary of the key advantages and disadvantages associated with every underground mining method based on their key mining indicators (KMIs). The selection method given in this paper is based on defining field KDIs and comparing them to the KDIs that are favorable to every considered mining method. By cross validating a matrix of favorable KDIs, the paper presents a simple approach to rank several underground mining methods using a scale from favorable to less favorable accordingly to the ore deposit characteristics (KDIs). KMIs are used to further complement KDI rankings by analyzing every method’s KMI performance based on the expected productivity of the mining operation being considered. To further assist the reader through the selection process, this paper gives basic sketches representing each of the primary underground mining methods discussed in this paper. Each method is given using the same 3D isometric view as spatial reference to assist the reader with visual interpretation and comparison between methods.

Jan 1, 2010

By Shenghui Chu, Zhibiao Guo, Dongshan Yang, Yuanxin Zhao, Xiaohui Kuai, Jingwei Gao

The technology of automatically formed roadway without pillars (AFRP) via roof cutting and pressure releasing (RCPR) is a reformatory method for gob-side entry retaining, which automatically creates a roadway by utilizing the fragmenting and expanding properties of rock strata and the mining pressure, to realize a novel technique for coal mining without coal pillars. The Anju Coal Mine is the first kilometer-deep mine where this technology is applied. To conduct a geomechanical model experiment, this research uses the 5307 working face in this mine as its backdrop. The experimental results show that this technology can efficiently decrease the pressure of the AFRP surrounding rock. The roof maximum stress of the AFRP is 21% lower than that of the belt roadway, while the side abutment pressure of the former is 13.4% lower than that of the latter. The comparison of model experiment data and field monitoring data shows that the roof and floor approaching deformations on the roof-cutting side and solid coal side of AFRP differ by 8.8% and 9.6%, respectively. The model experiment results and field monitoring data show good agreement, and the deformation of the AFRP surrounding rock can be successfully managed by this technique. The study’s findings can serve as a guide for using this technology in kilometer-deep coal mines.

Jul 31, 2023

By Jian Wang, Xiaoming Sun, Ming Jiang, Fuxin Shen, Chengyu Miao, Wenchao Zhao, Yong Zhang

The increased thickness of the coal seam leads to higher goaf roof collapse height. In contrast, the dynamic pressure from the mining of ultra-thick coal seams generates higher abutment pressures around the mined area and may affect the stability of roadways servicing these panels. To mitigate the deformation and damage issues in the roadways during the extraction of ultra-thick coal seams under a high depth of cover, researchers have proposed combining high prestress constant resistance support and roof-cutting technology (HPCR-RC). The deformation and failure mechanisms of the roadways during the extraction of ultra-thick coal seams under a high depth of cover, along with the mechanisms and field control effects of the combined support system, have been analyzed through theoretical analysis, numerical simulation, and field experiments. The research findings reveal that the high in situ stress, initial excavation disturbance, rotation, and subsidence of the fractured roof of the extra-thick coal seam led to significant deformation and damage in the roadways. High prestress constant resistance support compensates for the initial stress loss, reduces initial stress concentration, and absorbs deformation energy. Moreover, the roof-cutting technology severs the connection between the goaf roof and the roadway roof, disrupts the path of stress transfer, raises the level of roof backfilling in the goaf, and provides support to the roof, effectively alleviating the pressure on the coal pillar ahead and adjacent to the working face. Field experiments have confirmed the effectiveness of HPCR-RC, as indicated by a substantial decrease in surrounding rock deformation and support pressure within the roadways.

Sep 25, 2023

By Joel Lööw, Jan Johansson, Erik Lund

Digitalization and automation technology offer new possibilities to increase productivity and obtain higher levels of autonomy in mining operations. Introducing autonomous systems into mining is not only a technical problem in terms of effectiveness and efficiency, nor a problem of safety in human-automation interactions. The systems also need to be designed and developed so that they foster healthy and attractiveworking environments. The design and development phase of newmining technology has not been extensively studied previously. To fill this knowledge gap, we investigated technology developers’ basic assumptions about humans and their interactions with the technology they develop. We conducted five semi-structured workshops within an EU funded project concerned with developing digitalization and automation solutions for the mining industry. The data suggests that many critical functions will still be under human control in future mining systems. The results also indicate increased complexity in the interaction between autonomous systems and humans as the technology becomes more advanced. As a result, we suggest that a human perspective, based on sociotechnical principles, should not only be considered in implementing the technology at mines but also in the early conceptual phases of developing and designing the technology. This will ensure healthy and attractive work environments in the future mining industry.

Mar 26, 2024

By D. Gregurek

The complexity of metallurgical processes in the non-ferrous metals industry. especially changes in the process conditions in combination with a diversity of metal processing furnaces, requires a precise knowledge of the system for the selection of refractory products. However, particular importance is still focused on the specific refractory consumption being as low as possible. The addition of recycling material with a high amount of impurities and the increase of low-grade ore concentrates used in the base-metals industry also entails a significant change of slag chemistries, process temperatures, etc., which influence the performance of already approved linings. This acknowledgement of process changes with decreased brick lifetimes provided the motivation for RHI AG to develop high-performance refractory bricks especially for non-ferrous metals applications. The internal laboratory tests with fayalitic slag showed very promising results compared with our approved magnesia-chromite bricks for this application. In order to identify suitable refractory products and to improve the life of the refractory lining, innovative product development has to be undertaken. In addition, the practical corrosion testing methods and facilities available within the RHI Technology Center, such as the induction furnace and the rotary kiln test equipment, allows the best possible understanding of brick wear at a laboratory scale. Based on the results of the test work, the optimal refractory solution can be recommended for a field trial at the customer?s site.

Jan 1, 2012

By W. L. Falke

This Bureau of Mines report illustrates critical path planning and scheduling techniques as applied to typical mining operations. Detailed examples of arrow diagramming and computer oriented applications of critical path methods are given. Program Evaluation and Review Technique (PERT) is discussed briefly in comparison to the Critical Path Method (CPM).

Jan 1, 1966