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By B. T. Stanley

Traditional methods of creating a water tight shaft liner involve the use of segmented or welded steel. When shafts are located in ground that exhibits extremely difficult conditions of high water inflow and hydraulic pressure, composite liners are often combined with ground freezing during construction. The authors were searching for a cost effective and more flexible solution to hydrostatic liners design than the traditional concrete/steel composite design used so far. Searching through new technologies developed for tunneling applications, sprayed on membranes systems seemed very promising but were not developed for the specific circumstances encountered in shaft sinking applications where ground freezing is involved. Even though freezing is a very effective technique, it creates adverse temperature conditions for the application of spray on membranes. In addition, application and hydrating cure times for those membranes products ranged between six to twenty-four hours under ideal conditions (usually temperatures well above freezing point), which eliminated them from consideration in a shaft sinking cycle. While researching different spray on membrane materials, it was discovered that Stirling Lloyd Polychem Ltd. has developed and proven a different membrane material for waterproofing liners in different tunneling applications. The characteristics of the membrane exceeds the pressure parameters encountered in frozen shaft sinking operations, and the chemical cure times were reduced to one hour per layer which worked well into the shaft sinking cycle times. More over their system included a quality control procedure that allowed insuring integrity of the membrane at application time, a very desirable feature for shaft liner construction. However, the frozen rock surface still presented an unknown in the cure time and stability equation. As all membrane products a shotcrete substrate is usually required prior to application. The hypothesis used by the author was to use this shotcrete layer, not only as a substrate, but also as a thermal insulation against the frozen rock and the membrane during both application and curing time. The authors knew from experience that shotcrete could be applied successfully over frozen rock. But the shotcrete temperature curve over time was unknown and no information were found in the available literature. Testing was required to determine whether a suitable mix of shotcrete could be applied to the frozen shaft wall to provide enough heat of hydration for a suitable period of time to create conditions suitable for membrane application and curing.

Jan 1, 2012

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 N. Edmonson

The demand for sulfur divides into two major categories: agricultural and industrial. Most of the agricultural demand is related to the production of phosphate fertilizer products. Industrial demand is derived from the demands for a large number of products and is related to a variety of industrial processes, no one of which characterizes it in a simple way.

Jan 1, 1994

By E. Sabina Brady

Over the next two decades there will be significant trade and development opportunities in China for mining, engineering, equipment, and construction companies interested in becoming part of the development of China's chemical and fertilizer industries. At last count, China's phosphate ore reserves of 11.8 Gt (13 billion st), ranked fourth in the world behind the US, the USSR, and Sahara-Morocco. However, a recent statement by the head of the Ministry of Geology and Minerals, Sun Daguang, claims that with increased prospecting in the last few years, China's phosphate reserves now rank first in the world. Whatever the actual size of its known and potential reserves, China's present phosphate processing capabilities fall far short of demand, while the substantial progress that has been made in this area points out the severity of the problems that still remain. Since 1949 China has developed 181 mines and increased its phosphate concentrate production from 10 kt (11,000 st) to 10.86 Mt (11.97 million st). By the 1980s, China was the third largest chemical fertilizer producer in the world-although this claim is slightly misleading as China's nitrogen/phosphate potassium ratios are far from average world ratios and even further from US standards. According to the Sixth Five Year Plan promulgated in 1982, the country's development plans emphasize the expansion and upgrading of key energy and industrial sectors, including that of fertilizer production-specifically phosphate and potash. Within the framework of the plan, the Ministry of Chemical Industry's development priorities are to: • Increase potash production by 150% to 50 kt (55,115 st). • Raise phosphate fertilizer production 21.2% to 2.8 Mt (3.1 million st), 46 kt (50,705 st) of which will come from new projects constructed and completed within the Sixth Five Year Plan, with projected new production of phosphate concentrate and complex fertilizer in the next decades totaling 500 kt (551,146 st). • Commence work to increase phosphate ore production by 8.33 Mt (9.18 million st). Facilities for 2.43 Mt (2.68 million st) will be completed and come on stream by 1985. • Commence work to increase iron pyrite ore production by 3.69 Mt (4.07 million st), facilities for 2.9 Mt (3.2 million st) will be completed and come on stream by 1985. • Verify 600 Mt (661 million st) of new phosphate ore reserves. Since the promulgation of the Sixth Five Year Plan, Chinese authorities have announced that 70 key construction projects will receive top priority in the implementation of the plan. These projects include five in the chemical industry area, including the construction of four fertilizer plants in Urumqi (Xinjiang), Zhenhai (Zhejiang), Beijing, and Lucheng (Shanxi), and a pyrite mine in Yunfu (Guangdong). In addition, by 1985 the state will expand or construct three major phosphate mines: Wangji in Hubei, Kaiyang in Guizhou, and Kunyang in Yunnan. Fertilizer Ratios In 1982, China's fertilizer production was slightly higher than 12 Mt (13.2 million st) and consisted of 80% nitrogen, 19% phosphate, and 0.19% potassium. By 1985, state officials project that fertilizer production will reach 13.4 Mt (14.8 million st) and consist of 78.4% nitrogen (10.5 Mt or 11.6 million st), 21.2% phosphate (2.8 Mt or 3 million st), and 0.39% potassium (52.3 kt or 57,605 st). To attain the world average using the country's 1985 projected production level for nitrogen, China will have to double its 1985 phosphate production to 5.76 Mt (6.35 million st) and increase its 1985 potassium production almost 80 times to 4.1 Mt (4.5 million st). These numbers demonstrate the seriousness of the fertilizer production problem in China today and the long-term nature of the problem's solution. Development Examples Yunnan is the third largest phosphate-rich province in China with verified deposits of 1.9 Gt (2.1 billion st). Despite this abundance, the province only mines around 3 Mt (3.3 million st) of phosphate rock annually. In June of this year, Yunnan announced its intention to initiate 39 development projects within the next two and a half years, requiring an estimated $200 million worth of foreign investment. The three areas receiving the most emphasis will be:

Jan 9, 1983

The 86th Annual Meeting of the SME Minnesota section/74th Annual University of Minnesota Mining Symposium partnered with the Canadian Institute of Mining Metallurgy and Petroleum (CIM)?s Iron Ore Symposium for a historic joint conference, held this year in Duluth, MN, April 15- 17. One of a flurry of recent collaborations between SME and CIM, the joint conference was a natural fit for the conference held in the heart of the Iron Range. As CIM National President Terence Bowles said in his joint keynote with SME President Jessica Kogel, ?The U.S. imports $51 billion from Canada and Canada imports $38 billion the U.S.; that?s 50 percent of Canada?s exports and 51 percent of its imports.? The two countries? economies are linked, and nowhere more closely than in their iron ore mining activities. Kogel opened the conference with a plenary speech identifying the top 10 issues facing mining and how these issues present opportunities for mining companies. She said that it is important that the mining industry stay flexible and adapt to changing conditions, or it will go the way of the dinosaur. However, she said that these challenges can lead to new opportunities. For example, one of the major challenges facing mining is the current state of risk aversion among investors, which makes for ?less money in the pipeline.? However, this situation creates a better climate for mergers and acquisitions, which is another, less risky way to get funding. Likewise, another challenge globally is geopolitical risk; this challenge is likely to drive growth toward stable countries, which was good news for an audience composed mostly of Minnesota and Canadian mining industry personnel. One of the highlights of Kogel?s address was a triangle illustrating the interdependent nature of sustainable development and corporate social responsibility (Fig. 1). This triangle consists of four equal components: the social environment, transparency, local and global impact and future generations. The most important takeaway, Kogel said, was that sustainable development and environmental and social responsibility, while they do add to the cost of doing business, are no longer optional.

Aug 1, 2013

By B. R. Utz

The goal of the DOE Coal Preparation Program is to provide industry with the scientific and engineering knowledge base to produce economically competitive and environmentally acceptable clean coal products for both existing and new markets. The DOE/PETC in-house program continues to conduct fundamental, exploratory, and applied research in the areas of physical, chemical, and microbial coal beneficiation to assist in meeting these goals and objectives. The Coal Preparation Division now has a new Coal Preparation Process Research Facility that allows continuous bench-scale testing of emerging coal cleaning technologies and ancillary coal preparation equipment at feed rates up to 1,250 kilograms (1.25 tons) per hour. Bench-scale and laboratory-scale research projects at PETC cover areas such as 1) the use of micronized-magnetite for fine-coal, 2) heavy-media cycloning, 3) fine coal reconstitution, 4) development and testing of coal preparation process flowsheet simulators, 5) dry coal beneficiation using electrostatic methods, 6) tracer methods to determine the efficiency of density-based separations, 7) selective oxidation of organic sulfur, and 8) microbial removal of pyrite and organic sulfur from coal. This paper will discuss several of these research areas.

Jan 1, 1993

By G. R. Hart

The expected 1990 Clean Air legislation is providing electric utilities with a series of challenges and decisions as the utilities prepare strategies to comply with the resulting regulations. This paper addresses the strategy development of a coal-based utility --the legislation, the process used, the fuel issues, the options available, and the decisions to be made.

Jan 1, 1991

By J. G. Pippenger

The Coteau Properties Company's Freedom Mine is a surface lignite mining operation located near Beulah, North Dakota. As part of the mining process, Coteau removes and replaces thin layers of suitable plant growth material (SPGM) generally ranging in thickness between one and five feet. Historically, tractor-scrapers completed this work; however, rising tractor-scraper costs and increasing haulage distances sent Coteau in search of a lower cost method resulting in the acquisition of a backhoe/truck fleet in 1995.

Jan 1, 1997

By William H. Pelton

The presence of high-grade massive sulphides near York Harbour, Newfoundland has been known since the turn of the century. In the early 1900's a small, massive-sulphide deposit was worked by conventional hand methods and yielded about 100, 000 tons of high grade copper-zinc ore. Since that time, a number of mining companies have held options on the property and an exploration adit was driven along the fourth level of the original mine. Underground drilling revealed several additional massive sulphide lenses in the range of 10, 000 to 60, 000 tons (Fig. 1). The problem facing Long Lac Mineral Exploration Ltd. when they undertook an option on the property in 1969, was to outline any possible extensions to the known sulphide lenses which were outside the reach of underground drills and to search for new ore deposits which might double the known reserves into a feasible project for development. GEOLOGY AND PHYSICAL PROPERTIES: The geology is typical of many massive sulphide deposits within volcanic rocks in the Canadian Shield. The sulphide pods appear to occur along a complex andesite-basalt contact. Identification of the two volcanic types is difficult since they are almost the same colour. The most direct means of identification is by the slight difference in their magnetic susceptibilities. Pyrite, chalcopyrite and sphalerite are the main minerals in the sul¬phide lenses. The ore is massive, differing in density from the host rock by at least 1.0 gm/cc. There is little pyrrhotite or magnetite associated with the sulphides, so there is no appreciable difference in magnetic susceptibility between the sulphides and the basalt. Also, there is no alteration halo around

Jan 1, 1971

By C. J. Webb

Abandoned uranium mines in the southern Black Hills of South Dakota were sampled for uranium, radium, and rare earth elements during 1992 and 1993. Analyses of water samples from several shallow ponds in the mine pits showed pH values between 3 and 4 with uranium concentrations between 1600 and 2600 ppb. Rare earth elements and their respective isotopes were analyzed with an inductively coupled plasma mass spectrometer and were referenced to a shale normalization pattern. All samples showed an enrichment in the middle rare earth elements. Rare earth levels often were greater than 0.2 ppm. At one site, the concentrations of lanthanides were 150,000 times above background levels. While the southern Black Hills have long been known for rich uranium ore deposits, these analyses show that significant levels of rare earth elements also are present, indicating that the potential exist for future development.

Jan 1, 1995

By ZHONGLING ZHAO, WANTING SONG, GUOZHONG LIU, LEIXIN SHI, ZUI WANG, YUANYUAN LIU, KE GAO, DONGHONG JIANG, WANG LUO, PEICHAO LU, Jianwei Cheng, WANCHENG ZHENG, Gang Zhao, YUNGANG WANG, JIANBING ZHAO

Coal spontaneous combustion is one of the disasters occurring in underground coal mines. As a typical case, the spontaneous combustion of broken coal left in the longwall gobs often happen which could greatly interrupt the normal mining production. Such concealed thermal event is featured as rapid development and difficulty in locating “hot” spots. If such spontaneous combustion fails to be timely prevented and controlled, a large amount of toxic gases (mainly CO) and smoke could flow and diffuse in the underground working sections, which could present safety hazards for coal miners. In this paper, based on an coal spontaneous combustion event happened in a Chinese gassy mine, the fire ratios derived from the gas composition data obtained through the tube bundle mine atmospheric monitoring system are used in determining the fire status. A comprehensive and collaborative fire extinguishing effort including inert gas injection, underground pressure balance, and sealing enhancement are made to control the fire progress. Simultaneously, the effects of such works to control the spontaneous combustion event have also been quantified using the fire ratios to justify again. Finally, the danger of coal spontaneous combustion in gob is eliminated, and the longwall panel is successfully re-opened for normal production.

May 6, 2021

By P. Dhar, H. R. Kota, M. Thornhill

A very high-grade calcite deposit located in northern Norway consists of CaCO3 ore with minor silicate and sulphide impurities. Cationic (Tallow-1,3-diaminopropane, Duomeen T) collector has been used in the purification of calcite by flotation with an aim of achieving calcite concentrate for its use in value-added products in a variety of industries. The feasibility of sulphide flotation from calcite by this cationic collector has been initially judged from Hallimond flotation and zeta potential on pure mineral systems and the results illustrate the removal of sulphide from calcite ore at neutral pH region. The adsorption mechanism of diamine on both the sulphide minerals was found to be the same by zeta potential studies. The variations in zeta potential are in good agreement with the adsorption of diamine molecular and ionic species as a function of pH. FTIR studies also showed the adsorption of diamine species in agreement with the zeta potential and Hallimond flotation results. Furthermore, the removal of sulphide impurities with selective flotation by diamine collector was performed in bench-scale flotation with the calcite ore and the results indeed showed that the calcite concentrate could meet the quality requirements for its use in the paper industry for coating and filler purposes.

By Gunnar Nord, Per-Anders Persson, Duri Prader

The paper gives a short resumé of the findings of the joint US - Swedish "Mechanical Boring (MB) or Drill and Blast Tunneling (DB) ? Workshop" in Stockholm December 1976. New developments and trends in both MB and DB techniques in Europe since 1976 are described, and information is given on some interesting new projects. Differences in contracting principles between the US and Europe lead to different practices for preinvestigations, design, excavation and arbitration and legal affairs. It is shown that this often leads to a higher cost in the US than in Europe for similar excavation jobs. A typical US tunnel job also has more men on the site than a similar job in Europe. This adds to the cost difference and is only partly balanced by a slightly higher rate of excavation in the US. A comparison is made between two quantitative methods of predicting MB penetration rates. These are in reasonable agreement. A probable future development in machine design is an increase in cutter load towards perhaps 25 tons per disc where the tunnel diameter is large enough to house the machine size dictated by the size of the very large electric motors required. Recent European developments in drill and blast technique include improved methods for cautious blasting, precision hydraulic drilling of small diameter holes, and non-electric interval blasting techniques. These developments still keep the drill and blast method ahead of mechanical boring costwise for tunnels in igneous rock whereas for most sedimentary materials mechanical boring has a lead, particularly for long tunnels.

Jan 1, 1979

By William Gleason

"Speakers and attendees of the 2016 Cutting Edge Conference could not be faulted for keeping one eye on the presentations taking place at the Hyatt Regency at LAX in Los Angeles, CA on Nov. 7 and 8 and another on the results of the historic election in the United States that took place on Nov 8. While there was certainly interest in the presidential campaign, there was also a great deal of interest in Measure M on the California ballot. Measure M, which passed easily, is a half-cent sales tax increase that will fund the most ambitious transit expansion in Los Angeles County history.In the coming years, the ballot measure will transform a traffic-choked region by funding the construction of nearly a dozen new rail lines with an estimated $120 billion raised in four decades. Among the projects that could come to fruition are a twin-rail tunnels project through the Sepulveda Pass and new connections in the city.During the update on West Coast projects, Bill Hansmire summed things up with a slide asking “How much work is there on the West Coast,” and his answer was “Billions.”From Seattle, WA south to Los Angeles, there is already a lot of work for tunneling and underground construction experts, and Measure M ensures that there will be plenty of work for decades to come.Currently, The Los Angeles County Metropolitan Transportation Authority (Metro) has three rail projects underway that were funded by Measure R in 2008 — the Regional Connector, the Purple Line subway extension and the Crenshaw/LAX Line that are designed to alleviate the traffic pressure with an eye to more solutions.Measure M is the fourth sales tax increase to fund transportation in L.A. County, bringing the base sales tax rate to 9.25 percent. In some cities, which already levy their own sales tax, the rate would be higher, The Los Angeles Times reported.About 35 percent of the revenue will fund major new transit projects, such as the subway under the Sepulveda Pass, extension of the Gold Line to Claremont, extension of the Crenshaw Line to West Hollywood and acceleration of the Purple Line Subway construction along Wilshire Boulevard to finish in 2024, 10 years earlier than scheduled.About 17 percent would fund a dozen highway improvement projects, such as widening parts of I-5 in the Antelope Valley and southeastern county, adding bus lanes to the Sepulveda Pass section of the 405 freeway and adding truck-only lanes to a section of the 710 freeway."

Dec 1, 2016

By Jr. Moulton

Extractions of minerals from Searles Lake brines have taken place since 1873. Early operations were for borax and raw trona found on the surface, expanded after 1914 to include potash, salt cake, and soda ash. A new soda ash plant now in operation will double area production. The evaporite beds were formed by desiccation of Eastern Sierra runoff. The resulting series of brine-bearing salt beds supply the fluids necessary to feed the area chemical plants. Production methods include evaporation and crystallization for potash, borax, and salt cake; carbonation of brine to recover soda ash; and organic extraction of borax.

Jan 1, 1980

By Naoko Shimazaki, Andre Xavier

Over 10 million tourists have visited Vietnam in 2016. Travel and tourism accounted for 9.3% of the country’s Gross Domestic Product (GDP) in 2014. At the same time, as with many other resource-rich developing countries, Vietnam has been developing its extractive resources sector as a means of promoting the country’s social and economic development. In 2015, mining was the third largest contributor to GDP, and accounted for 8% of Vietnam’s gross domestic product. Vietnam is the third largest mineral producer in SE Asia. Although it produces zinc, nickel, bauxite, and manganese, coal mining is its most developed sector. The country has over two hundred coal mines, and total reserves of approximately 6 billion tons. Quang Nihn Province, where the World Heritage Site Ha Long Bay is located, is a very important tourism destination. It is also a coal-rich region where mining extraction and processing have been active since the early 20th century. Vietnam is signatory of the United Nations Sustainable Development Goals (SDGs). The country is aware of the importance and the challenges involved in managing the extractive sector in a way that does not undermine its tourism industry and yet that contributes to the country’s sustainable development. To this end Vietnam is taking actions towards implementing more advanced coal-mining extraction and processing techniques. The country is furthermore promoting a responsible mining sector, and is investing in programs that foster environmental protection and sustainable tourism. This paper examines the case of the Ha Long Bay region and the project involved in relocating the Hong Gai coal preparatory factory from a seafront area to a mountainside area. This paper provides a preliminary review of the initiatives adopted by the government of Vietnam to address the existing challenges that have resulted from a focus on promoting the country’s socio-economic development through the exploration of its rich coal endowment. Furthermore, it also describes Vietnam’s legal and policy frameworks. In conclusion this study identified that Vietnam has drafted a National Action Plan to implement the Sustainable Development Goals. The country is also taking an integrated approach to implementing the SDGs agenda and that it is assigning responsibility to a variety of ministries to achieve SDGs’ specific targets. Furthermore the country is changing policies and the legal framework in order to facilitating the execution of the work of agencies that are responsible for implementation, regulation and enforcement. In this respect, the approval of the National Action Plan on Sustainable Development Goals is another important step in that direction. While the decision of supplying its internal market with high quality coal helps minimize negative environmental impacts in Vietnam, exporting low quality coal to other countries does not help resolve the problem of CO2 emissions globally. With respect to the 2030 Agenda, this may be considered a temporary solution since to achieve the SDG goals, Vietnam will have to consider other sources of cleaner energy in order to align with the Sustainable Development Goals # 7 on affordable and clean energy.

Jan 1, 2017

By H. C. Rolseth

The first step in the quarrying of granite, following removal of any overburden material, involves the freeing of large blocks from the formation. For many years the use of explosives was the accepted method of obtaining these blocks. Even today there are operations where this is considered to be the most economical method even though it does result in a high percentage of damaged stone. In more recent times the preferred procedure at most quarries has been to produce a continuous vertical cut or slot completely around the block to be separated. Originally, this was done by drilling a series of closely spaced holes around the block and breaking the web between the holes with a chisel-like tool known as a broaching bar. The machine used in this mechanical method of producing the relief slot is known as the channel bar. The modern day approach to the production of continuous channels was introduced to the industry around 1955 by the Linde Division of Union Carbide Corporation. The method employs a small rocket - jet burner producing a high temperature, high velocity exhaust flame which when directed against the granite causes it to disintegrate. This method, which has come to be known as "Jet Channeling", is now used by practically every major granite producer in the United States and Canada.

Jan 1, 1968

By M. J. Klishis

This paper presents the findings of a study on roof bolters' hazard exposure. A "micro-analysis" of accident data was combined with ergonomic observations of roof bolter operators to categorize bolting-related injuries and a checklist was constructed. Bolting-related problems were identified as situations that could expose bolter operators to hazards. Approaches to avoid these situations were applied at six mining operations to evaluate specific problems in roof bolting operations. The re-search emphasized the importance of analyzing worker behaviors in the context of mining situations and equipment design problems that lead to human error accidents.

Jan 1, 1995

By Kumara S. Rachamalla

Long-term stability, appropriate taxation and incentive policies are essential to attract and stimulate investment in the mineral sector. An outline of Ontario's $4.6 billion industry and associated tax incentives is presented. Producers are offered incentives under The Mining Tax Act, federal and provincial income tax acts for exploration and development by reducing Me after tax cost to 13-25¢ for each dollar spent. The Mining Tax Act provides generous processing incentives which have positive effects in enhancing investment and economic advantages of building processing facilities. Non-mining companies and entrepreneurial individuals can receive 25% of eligible exploration expenditures in grants/tax credits under the Ontario Mineral Exploration Program.

Jan 1, 1982

By A. D. S. Gillies

Loss of visibility due to the occurrence of atmospheric fogging in underground mine airways can lead to a reduction in travel times and loss of production efficiency, an increase in the frequency of vehicular and foot traffic accidents and difficulty in checking rock surfaces for instability and loose material. Where hot and humid surface air meets colder underground air, conditions for fog formation nay be present. Further, suspended particulate matter from diesel exhausts or stoping operations together with slow movement of air along passageways nay contribute to formation. The study describes an investigation being undertaken with the cooperation of Kennecott's Ozark Lead Company to identify causes of the problem.

Jan 1, 1982