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By Fuming Wang, Lifu Hu, Changrong Li, Ruipeng Pang

The solidification structure of 430 ferritic stainless steel has been calculated in the solidification process by using 3D-CAFE model under the condition of water cooling. The calculated results consistent with those obtained from experiment. Under watercooling condition, the solidification structure consists of chilled layer, columnar grain zone, transition zone and equiaxed grain zone

Jan 1, 2015

By Kexin Jiao, Huichang Song, Zhijia Zhang, Jianliang Zhang, Zhengjian Liu

A clear understanding of iron carburization reaction occurring between molten iron and carbonaceous materials is of great importance in blast furnace, and it is one of the hot spots that ironmaking workers pay close attention to. Although carburization rates between iron and coke have been studied, the factors directly controlling it have not been clearly identified. This study focused on the kinetics analysis of iron carburization reaction. Sulfur content was determined as having positive influence on graphite carburizing reaction rate in the range of 0.02% - 0.06%. The values of apparent activation energy calculated by the experiment are consistent with the existing literature, which in turn proved the reliability of the experimental data.

Jan 1, 2015

By I. U. Onyenanu, C. E. Ilochonwu, E. I. Nwonye, C. O. Nwajagu

This work shows how pure silica was derived directly from rice husks ash (RHA) in different temperatures for reduction to Silicon (Si). The processes to form Si materials are usually complex, costly and energy-intensive. The silica in the ash undergoes structural transformations depending on the conditions of combustion. A high purity silica was produced at 650oC after burning the rice husk (RH) for up to 7 hours. The purity of the silica was determined by dissolving the RHA with alkali solution to form sodium silicate solution of pH 11.0. This was added to hydrochloric acid of pH 1.5 which lowered the pH of the solution to 4.0 to form silica gels. The silica gels produced were washed and dried to powder and then characterized using XRD and EDX techniques. This study was done to reduce energy waste and environmental pollution in Nigeria as silica is used to develop many materials.

Jan 1, 2015

By Huanyu Zhang, Quanqiang Ma, Huiqing Tang

Improvement of the coke quality for blast furnace (BF) iron making by hydrothermal oxidation treatment on coke quality was investigated. Results show that, under subcritical condition, sulfur removal rate is 15% and the weight loss is 3%; under supercritical condition, both sulfur removal rate and mass loss rate increase with the increase of H2O2 concentration. In the experimental conditions, sulfur removal rate and mass loss rates were 45% and 17%, respectively. Hydrothermal oxidation treatment could reduce the CO2 reactivity of the coke and the treatment under supercritical condition is more effective. Hydrothermal oxidation treatment could improve the graphitization of the coke and smoothness of pore boundary in the coke and the treatment under supercritical condition is more effective.

Jan 1, 2016

By Guangliang Wu, Dong-chang Huang, Xin-bin Liu

High temperature mechanical properties of 50Cr5MoV roll steel was investigated by Gleeble 1500 thermal simulator testing machine The morphology, composition and microstructure of fracture surface were observed and analyzed by OM, SEM and EDS The results are indicative of that, there are two brittle temperature zones of 50Cr5MoV roll steel at the temperature of 600°C~950°C and 1300°C~1450°C, respectively. The section shrinkage rate is less than 60% The fracture mode changes from mixed ones dominated by intergranular to toughness transgranular one with the increase of temperature at the range of 650°C~1300°C. The fracture is along the solid--liquid phase at the range of 1300°C~ melting point It is crucial to formulate the 50Cr5MoV casting technology, to prevent the cracks and improve the quality of 50Cr5MoV roll steel.

Jan 1, 2016

By Jonathan K. Hrica, Brianna M. Eiter

The ability to identify hazards during a workplace examination is a critical skill for mineworkers to have in order to maintain a safe workplace. While research suggests that being able to successfully recognize hazards requires a complex set of competencies, it is unclear which competencies are most critical to adequately perform a workplace examination. This paper presents a hazard recognition competencies framework as an explanation of the competencies that affect mineworker hazard recognition. To better understand how the industry is selecting and preparing workplace examiners, researchers from the U.S. National Institute for Occupational Safety and Health (NIOSH) interviewed nine health and safety (H&S) professionals at surface stone, sand and gravel mine sites throughout the United States. These interviews verified that the competencies included in the hazard recognition competencies framework agree with perceptions of the interviewed H&S professionals, who also provided validity for the critical role these competencies play. Finally, the results of this study are presented within the context of current NIOSH research findings related to hazard recognition.

By J. R. Patts, A. B. Cecala, E. J. Haas

Exposure to respirable crystalline silica (RCS) remains a serious health hazard to the U.S. mining workforce who are potentially exposed to RCS [1,2] as various ore bodies are drilled, blasted, hauled by truck, crushed, screened/sized and transported to their destinations. To examine a method for assessing RCS exposure using a NIOSH-developed video exposure monitoring (VEM) technology (referred to as Helmet-CAM), video and respirable dust concentration data were collected on 80 miners across seven unique mining sites. The data were then collated and partitioned using a thresholding scheme to determine exposures that were in excess of 10 times the mean exposure for that worker. Focusing on these short-duration, high-magnitude exposures can provide insight into implementing controls and interventions that can dramatically lower the employee’s overall average exposure. In 19 of the 80 cases analyzed, it was found that exposure could be significantly lowered by 20 percent or more by reducing exposures that occur during just 10 minutes of work per eight-hour shift. This approach provides a method to quickly analyze and determine which activities are creating the greatest health concerns. In most cases, once identified, focused control technologies or behavioral modifications can be applied to those tasks.

By L. Yuan, D. Bahrami

Underground mine fires remain a concern for mine operators, posing a health and safety risk to mineworkers. In the last decade, the number of mine fires has decreased significantly. However, dealing with an unknown fire in underground mines can be a challenging task, which could lead to a hazardous condition for miners during an evacuation and rescue operation. A timely detection of a mine fire and monitoring its characteristics—namely, size and location—are of great importance in reducing the risk of mine fire injuries. A new, improved fire location algorithm has been developed and integrated into an atmospheric monitoring system (AMS) program by researchers from the U.S. National Institute for Occupational Safety and Health (NIOSH). This paper describes the new fire location model and presents the results of verification fire tests conducted at the Safety Research Coal Mine (SRCM) facility of the Pittsburgh Mining Research Division (PMRD) using the collected AMS data. NIOSH is endeavoring to develop workplace solutions to improve the detection of and reduce the risk of hazardous conditions in mines. The results demonstrate successful application of the improved fire location model and provide a useful tool for solving the problem of unknown fire location and reducing the risk of hazardous conditions.

By Anthony Iannacchione, Tim Miller, Nicole Evanek

The Subtropolis Mine is a room-and-pillar mine extracting the Vanport Limestone near Petersburg, OH. In February 2018, mine management began implementing a new mine layout to better control the negative effects of excessive levels of horizontal stress. Almost immediately, the conditions in the headings improved. Conversely, and as expected, stress-related damage was concentrated within crosscuts. Over the last 18 months, the mine operator has diligently experimented with different techniques/methods to lessen the impact of the instabilities in the outby crosscuts. The range of controls used by the mine operator include angled crosscuts, crosscut offsets, increased distance between crosscuts, arched crosscuts, cable-bolted crosscuts, altered blasting pattern, and windows. A window is used to resist roof deformation by leaving a strong brow of roof rock within the crosscuts.

By J W Shields

The aim of this paper is to present a concept or model regarding a particular geological environment where gold orebodies occur in the Pine Creek Geosyncline and indeed in many other pans of the world. The name GIGIACS (an acronym for Gold In Greywacke In Anticlinal CrestS) is proposed to label this concept or model. The name Saddle Reefs (which has been in use for many years) is used for gold-bearing quartz veins which often occur in conjunction with Gigiacs. Simple patterns formed by this type of mineralisation at the surface due to different configurations are illustrated. Some examples of Gigiacs and associated saddle reefs are presented from the Pine Creek Geosyncline together with examples from other parts of the world. This concept has been used successfully as an exploration tool and five examples are given. The terms Gicsiacs (for Gold In Carbonaceous Shale In Anticlinal CrestS) and Giliacs (for Gold In Limestone In Anticlinal CrestS) are also used.

Jan 1, 1994

By Russell Webster

In having maintained production for more than 40 years Arizona's Magma mine is unique in a mineral district that includes several major copper mines. Other past and present producers in this area are Miami and Inspiration at Miami, the Old Dominion in Globe, the Ray mine in Ray, and to the south the new San Manuel mine near Tucson. Magma's production of copper, silver, gold, and some zinc has come from nearly parallel east-west striking mineralized faults, one called the Main or Magma vein and the other the Koerner vein, about 1100 ft to the south. This vein system has been prospected and partially mined for some 9000 ft horizontally and 4800 ft vertically. In ascending order from the deepest exploration level, the Main vein cuts Pre-Cambrian schist, Pre-Cambrian Apache Group, Post-Devonian diabase, and Devonian, Mississippian, and Pennsylvania limestones. Until 1950 very little ore was obtained from replacement mineralization.

Jan 10, 1958

By Pedro Morales

At present the Codelco´s smelter & refinery business have growing complexities, concentrates with lower copper grades, higher impurities contents, and environmental restrictions which have lead to refocus the Codelco business, not only by considering the isolated developments for each of the Codelco´s Smelt & Ref complexes, but also as an integrated corporative complex scheme which improve the economy of scale, optimize the synergies, and include new technologies for higher productivity and lower operational costs. Accordingly, for the 2008-2012 period, Codelco have prepared a Development Plan integrated to the smelters and refineries business units that improve its single potentialities of and include the advances for the Teniente Converter [1] and Continuous Converting [2] Technologies, and also include the concept of uncoupling the smelting process from the converting process allowing a higher operational flexibility, and a better control of its contaminants. Thus, processing the white metal generated in the Teniente Converter unit of the smelter A into the smelter B has comparative advantages. These changes in the business concept allow an overall increment of the smelting capacity by processing only white metal as a final product through a very marginal investment in this way the total or partial conversion of the white metal into blister copper is eliminated allowing to use the available gas capture-treating capacity, and available acid plants for increase smelting capacity as well.

Jan 1, 2006

By Chung Yu, Wang

CHINA can he roughly divided into three metallogenetic province: North China, the Yangtze Valley, and South China. In North China the old Pre-Cambrian schists and gneisses are represented by the abundance of quartz mines in which sporadic occurrences of copper, lead, zinc, gold, and silver are sometimes found in subordinate quantities. Along the Yangtze Valley and in Central China, extending eastward as far as Shantung, are found here and there intrusions of dioritic rocks, in which occur the famous contact deposits of iron ore, besides which minor quantities of copper. lead, and zinc are also found. In South China the igneous intrunsions are of granitoid type in which, or in the vicinity of which, occur in certain regions immense deposits of antimony, tungsten, tin, and mercury. Broadly speaking. most of the famous coal mines are now situated in regions north of the Yangtze River, in which occur also the sedimentary deposits of iron in contradistinction to the contact deposits of iron along the Yangtze Valley.

Jan 1, 1943

By J. R. Gaw

Recent events pertaining to U. S. energy needs and development of alternative energy fuel resources have made the American public more aware of past and present coal mining operations, and their impacts on the nation's economy and environment. This awareness has developed rapidly due to increased government involvement and consequent media coverage. This is true particularly in the Western states and in Texas. One of the consequences of this increased public awareness is public concern over the perceived and real consequences of mining operations. Emphasis has been placed on potential releases of toxic and hazardous substances, and possible carcinogens. The result of this public concern is a mounting effort at both state and Federal levels to promote stricter laws regulating the mining industry.

Jan 1, 1992

By Mario Sanchez, Jose Palacios, Fernando Parada

Carbon steels have less than 0.02% copper and have low atmospheric corrosion resistance. The addition of at least 0.20 wt% Cu improves this property. Also, 0.8 wt% Cu in steel shows a hardening potential for developing high strength corrosion resistant steels. Copper slags containing 42–45% of iron, silica and minor amounts of copper were used for producing Fe–Cu alloys by reducing the oxides contained in the slag to obtain a Fe-0.84 wt% Cu alloy, which could be suitable as feeding material to manufacture a corrosion resistance steel, and also would be an alternative for minimizing the copper industry ’s environmental impact, and to introduce the application of the Circular Economy concept to the natural resources exploitation, especially in countries where their economy is strongly based in mining and metallurgical extraction.

Mar 1, 2018

By J. C. Stankus

Many coal seams are associated with soft floor strata and during mine development if coal pillars are not properly designed, floor heave occurs and causes interruption of coal production. In the severe cases, the section or mine is abandoned. One of the methods for controlling floor heave is floor bolting. This paper describes the demonstration of floor bolting methods in a West Virginia coal mine. Three methods were used: (1) vertical full resin bolting, (2) floor truss bolting, and (3) floor truss bolting plus a floor cut at the center of the entry. The design of each method and the experimental results are discussed in detail.

Jan 1, 1993

By Michael Somerville, Paul Voigt, Chunlin Chen, Alistair Burrows

To date, many types of primary concentrate have been smelted using the ISASMELT™ technology, with annual smelting of copper concentrate alone exceeding 7 million tonnes. Most of this material could best be described as chalcopyrite concentrate, owing to the predominance of copper attributable to this single mineral. Chalcopyrite concentrates lend themselves readily to smelting with a fayalite slag, and producing a matte containing 55–65 wt% Cu. However, the ISASMELT™ technology also stands ready to meet future copper demand through the treatment of new types of concentrates containing relatively low iron and high silica levels. Various slag systems have been considered for direct-to-blister smelting. They have been evaluated computationally, using the MPE thermodynamic modelling package, and practically, at pilot scale. The lime-silica-iron oxide slag was found to have the lowest slag make, lower dissolved copper and hence lowest copper losses. Based on the outcomes of the modelling and pilot scale testwork a future smelter flowsheet has been defined, comprising a single ISASMELT™ direct-to-blister furnace, an electric slag cleaning furnace, and appropriately designed anode furnaces.

Mar 1, 2017

By Dachun Liu, Xutao Guo, Wenlong Jiang, Baoqiang Xu, Bin Yang, Yong Deng, Heng Xiong

Typical copper dross, the byproduct of lead bullion pyrometallurgical refining for copper removal, mainly contains Pb, Cu, S, As, Sb and Sn etc. In traditional treatment process, copper dross is transformed to be copper matte by smelting with iron scarp and iron pyrite. Here, a new treatment process of converting-vacuum distillation (CVD) was proposed and investigated. Based on this concept, the converting process was tentatively investigated in this paper. The results of element distribution of converting samples showed the sample has three layers. The upper layer is mainly sulfides of lead and copper, the middle layer is mainly copper arsenide, and the lower layer is lead arsenide and crude lead. On the condition of oxygen flow rate 400 ml/min, the converting temperature 1000 °C, the holding time 1 h, the converting time 10 min, the lead copper alloy containing 0.17% S was obtained.

Mar 1, 2018

By Shengping Li, Wei Lv, Gangqiang Fan, Xuewei Lv, Yingyi Zhang

The electrical conductivity of high titania slag, as being an important fundamental physical property utilized in the theoretical understanding of mass transfer phenomena and requirement of practical electric smelting processes, were measured by AC Impedance Spectroscopy using four-electrode method for ternary TiO2–FeO–Ti2O3 slag system based on 85 type of titania slag in Panzhihua in this work. The experiment results show that the slags have a high magnitude of the order of 80–180 s/cm−1 in the whole experimental temperature range from 1523 to 2013 K. The Ti2O3 exhibits very strong effect on increasing the electrical conductivity of high-titania slag since the specific values averagely increase by 55 s/cm−1 with corresponding Ti2O3 content range from 10 to 16 wt%. the X-ray diffraction gram and phases calculated by FactSage are presented and interpreted to discuss the impact of phase change on the electrical conductivity.

Mar 1, 2017

By Sergio Neves Monteiro, Fabio Da Costa Garcia Filho, Dian Souza de Oliveira

The properties of the nickel based superalloys, in particular 718 nickel-based alloy, are mainly improved by the hardening mechanism, which is based on precipitation of second phases. This work aimed to compare the evolution of precipitation hardening in a 718 alloy microstructure for two different solubilization conditions: 1050 °C for 2 h and 970 °C for 2 h, followed by a period up to 120 h of aging at 800 °C and correlated to the values of hardness. The microstructure was analyzed by optical microscopy. Vickers hardness test was performed and the grain size was measured. It was verified an increase on the hardeness of this material up to 15 h of aging, after that the value decreased to a level that is maintained until 120 h for both solubilization conditions.

Mar 1, 2018