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By Michael G. Zabetakis, Aldo L. Furno, George H. Martindill

Hydrazine vapor is flammable in the absence of air at elevated temperatures and atmospheric pressure . The minimum concentrations of benzene , toluene , m- xylene , cumene , and n- heptane needed to inhibit flame propagation through vapor mixtures of hydrazine and hydrocarbon were determined at 125 ° C and atmospheric pressure . These concentrations can be correlated with either the heat of formation or the heat capacity of the hydrocarbon .

Jan 1, 1964

By M. Izadi Yazdan-Abadi, S. H. Amiri, M. Ramezanizadeh, M. Bazmandeh

Iron ore concentrate is used as the fresh feed of pelletising plants. The green pellet properties depend on iron concentrate characteristics such as particle size distribution (PSD), specific surface area (Blaine value), iron grade, moisture content and grinding methods. The grinding methods affects particle size distribution and Blaine value. To find out the effects of grinding methods on pelletising process, green pellets were produced with concentrates that were reground by means of HPGR (high pressure grinding rolls) and ball mill. The Blaine values of ground concentrates in both types of milling were approximately 1400, 1600 and 1800 cm2/gr. The results of green pelletising tests on a pilot plant scale showed that at the same Blaine values, drop numbers of green pellets produced by ground concentrate inside HPGR were higher than the green pellets produced by ground concentrate inside a ball mill. Also, reground concentrates by means of HPGR, in comparison with ball mill, caused the production of green pellets, at higher wet and dry compression strengths. As a result, it was found that preparing the pelletising feed by means of HPGR led to more positive effects on the properties of green pellets. Keywords: Ball mill, HPGR, green pellet, drop number, wet and dry compression strengths

Jan 1, 2020

By R. Mumbi, M. Peart, E. Arinaitwe, B. Mbao, J. Zulu

Since 1925, xanthates have been widely used in sulfide flotation due to their low cost, ease of manufacture, and ability to float most value species. However, the industry's increasing need for safer and more selective alternatives, driven by low head grades, poor-quality, difficult-to-process ore with complex mineralogy, and stricter environmental regulations, has led to the development of Solvay's AERO® XR series of collectors. These custom-formulated products are based on greener chemistries and offer metallurgical benefits that are similar to or better than those of xanthates, without the safety concerns. Developed through Solvay's Flotation Matrix (FM) 100 approach, the XR series collectors are suitable for a wide range of applications, including the processing of Cu, Zn, and Cu-Ni, as well as the flotation of precious metals. This paper will highlight the differences between xanthates and XR series collectors, and present case studies of their successful commercial application at various global operations.

Jan 1, 2023

By D R Van Eck

Western Deep Levels, a seismically active deep level told mine. stalled placing backfill in their narrow tabular workings as part of the regional support strategy in 1986. Over the years the percentage of working places being backfilled has been gradually increasing. At the end of 1995 the support efficiency and the labour productiveness relating to support installation were scrutinised to determine if resources were being optimised. Owing to financial, safety and productivity constraints it was decided to redesign stope support to be less labour intensive, safer and provide an integrated stope support system. This new integrated system will thus combine the previously used temporary, permanent and back area support consisting of mechanical props, hydraulic props and backfill respectively. Backfill previously formed an integral part of the regional support in conjunction with strike stabilising pillars. To design the integrated support system the backfill placement quality has to be exceptionally good and placement must be done as close as possible to the working face. The backfill to face distance was reduced by 30 per cent and in some areas by more than 50 per cent with an increase of square metres filled to increase the effect of the backfill even more. This paper addresses the design and successful implementation of an integrated stope support system based on the optimisation of backfill to he extent where installation of mechanical and hydraulic jacks could he Eliminated

Jan 1, 1998

By R R LARGE

In the past decade mineral deposit models have become an important tool for the exploration geoscientist. By combining genetic theories on the formation of particular deposit styles, with geological, geochemical and geophysical criteria relevant to ore location, it has been possible to more effectively focus exploration effort to the regions and local targets which have the best chance of success. However, such models have their limitations, and must be carefully and critically applied and continually updated as new technical and research information becomes available.

Jan 1, 1992

By Jaroslav Briancin, Katarína Gáborová, María Florencia Márquez-Zavalía, Marcela Achimovičová, Ol’ga Šestinová, Pavel Škácha

Naumannite (Ag,Se), a silver selenide mineral, was first discovered in 1828. This study investigates the structure, morphology, chemical composition, and leaching kinetics of naumannite. Mechanical activation in a planetary ball mill increased its specific surface area, enhancing the leaching rate of silver in nitric acid (HNO3). The study found that mechanical activation significantly improves silver recovery.

Jul 1, 2023

By H. H. Schrenk

One phase of the Bureau of Minest work in the field of health and safety is the promotion of safe, satisfactory, and reliable respir atory protective devices. To insure that such devices will be available, the Bureau has established schedules of what it considers the minimum re- quirements for oxygen breathing-apparatus,3 gas masks, hose masks,5/ and mechanical filter-respirators (a schedule of requirements for hose- type supplied-air respirators is being prepared). Approval of oxygen breathing-apparatus is given by the Safety Division; approval of other types of respiratory equipment is given by the Health Division, both divisions being in the Health and Safety Branch, Manufacturers of respiratory protective devices may submit their equipment to the Bureau for approval under the requirements of these schedules. As a prerequisite to submitting a device for approval, the Bureau requires a statement that the device is completely developed and of the design and material that the manufacturer believes suitable for a finished marketable device; that the device has been

Aug 1, 1937

By Guangwei Wang, Changle Zheng, Yifan Chai, Jian Guo, Weiwei Geng, Jianliang Zhang

In this paper, characteristic and kinetics of CO2 reaction with four different kinds of coke such as top-loading coke, dry quenching tamping coke, wet quenching tamping coke and semi-coke were investigated based on isothermal method. Electric resistance reduction furnace was used to heat the sample. Volume Model (VM) and Shrinking Core Model (SCM) were used to calculate the kinetic parameters and to contrast with the experimental results. The results showed that the Volumetric Model (VM) was much suitable for the reaction of top-loading coke, dry quenching tamping coke and wet quenching tamping coke, while Shrinking Core Model (SCM) was much suitable for semi-coke.

Jan 1, 2015

By Yang Hai-long, FAN Gang, LI Cun-xiong, WEI Chang, LI Min-ting, LI Xing-bin, DENG Zhi-gan

Hydrothermal sulfidation of pure cerussite with elemental sulfur has been reported in the present paper. The variables considered in the study were temperature, time, particle size and elemental sulfur fraction in the reacting mixture. Temperature was the most important factor at temperatures above 180 , PbS and PbSO4 were the only stable reaction products in the sulfidation of cerussite. The experimental data indicated that under the hydrothermal conditions with a particle size of -74+58 μm and sulfur fraction in reacting mixture of 15% at 200 °C for 120 min, and 92% of lead sulfidation rate was achieved.

Jan 1, 2016

By J A Evans

A well-maintained and low cost mining operation today requires the use of condition monitoring techniques. At ERA - Ranger Mine oil analysis, vibration monitoring, infra-red themtography, and performance analysis have been successfully applied over the last four years to lower operating and maintenance costs. All condition monitoring is scheduled through a comprehensive in-house developed maintenance management system known as the Engineering Information System (EIS). (EIS) is used extensively at Ranger to ensure consistent frequency and recording .of all condition monitoring data. This paper provides an insight into the benefits of condition monitoring and explores the future direction for condition monitoring techniques at Ranger.

Jan 1, 1994

By A. Martikainen, S. GYAMFI

Luossavaara-Kiirunavaara Aktiebolag’s (LKAB) Konsuln iron ore mine, located just south of the famous Kiruna iron ore mine in Malmfälten in northern Sweden inside the Arctic Circle, was developed as a test mine between 2018 and 2020 for the Sustainable Underground Mining (SUM) project [1]. Besides functioning as a test mine, Konsuln also contributes to ore production. The existing mine ventilation system was designed for the current production rate of 0.8 Mtpa using conventional diesel machines. The design was created by Kiruna mine ventilation team, Stina Klemo and Joakim Jonasson, in cooperation with a consultant, Tomas Bolsöy from EOL Vent Mining AB. There is a plan to increase this rate to between 1.8 and 3 Mtpa in the future, and this requires the primary fans to be upgraded. Therefore, a study was carried out to determine whether using ventilation on demand (VOD) could avoid this fan upgrade and reduce Konsuln’s ventilation and heating power costs in the future. The study also investigated whether using battery electric vehicles (BEVs) along with VOD or as a standalone strategy could further reduce these power costs. In addition, the study analyzed the suitability of heating power reduction strategies presently or previously used in Nordic countries and Canada to investigate potential additional strategies to reduce heating power cost, the largest portion of Konsuln’s ventilation and heating power costs.

By Thomas F. Clemens

This paper covers various changes in government regulations, taxation, and legislation for the past two plus years and the up- coming one. Part of the paper will discuss recent business conditions and how they have affected the cement and lime industry.

Jan 1, 1983

By Jagger ND

Pressure filters were found to be necessary to produce Elura silver/lead and zinc concentrates at sufficiently low moisture contents for bulk cargo shipment by sea to smelters.The difficulty in obtaining low moistures was due to the fine primary grind, 80% passing 45 microns, and resultant fine concentrates, 97% passing 45 microns.The filtration system was designed to filter up to 90,000 tonnes/year silver/lead concentrates and up to 130,000 tonnes/year zinc concentrates.This paper details the preliminary test work to select Larox automatic pressure filters, and the commissioning and operation of these filters to achieve design criteria for both concentrates. The design criteria for both concentrates have been bettered due to the concentrates being coarser than the design sizing.

Jan 1, 1985

By C. N. Logan

The Southern Company is one of the nation's largest electric utilities and is the parent firm of five operating companies: Alabama Power, Georgia Power, Gulf Power, Mississippi Power and Savannah Electric and Power. Another subsidiary is Southern Company Services (SCS) which provides engineering and technical sup-port to the five operating companies. This technical support includes the procurement and supply of over 40.9 Mt (45 million st) of coal annually for the 22 coal fired plants in the system. Approximately 80 percent of this tonnage is purchased under long term contracts and the remaining 20 percent is purchased on the spot market. The coal is principally supplied from Alabama, Illinois Basin and the eastern Appalachian coal fields. Most of the coal is delivered by unit train and barge but one plant in Alabama receives all its coal by truck and conveyor belt.

Jan 1, 1990

By Shigeru Ueda, Shin-ya Kitamura, Shohei Koizumi, Xu Gao

Steelmaking slag was confirmed to be a useful fertilizer for paddy growth as it efficiently supplies Ca and Si to soil water. In addition, supplement of Fe from slag fertilizer has been expected to suppress the H2S generation in paddy soil, especially for the degraded paddy soil. However, on the basis of our previous research, the Fe dissolution ability changed with slag brands, and even some brands could dissolve Fe under paddy soil pH, the supplying ability were not high. To improve Fe dissolution, we found that among various kinds of Fe-rich mineralogical phases in slag, the CaO–SiO2–FeO glassy phase showed highest water solubility of Fe. Because the CaO–SiO2–FeO glassy phase was a quenched molten phase, its dissolution behavior may depend on chemical composition, and this is important for controlling slag composition to produce fertilizer which can easily release Fe. Therefore, in this research, the CaO–SiO2–FeO glassy phase of various CaO/SiO2 ratio, Fe2+/T–Fe ratios, and FeO contents were synthesized, and the dissolution behaviors of Fe as well as other cations from these synthetic glassy phases into an aqueous solution at pH of 5 were investigated. The result showed that the dissolution ratio of Fe increased significantly by increasing Fe2+/T–Fe ratio. An increase in FeO content of glassy phase also increased the dissolution of Fe. In addition, the Fe dissolution ratio showed a local maximum with increasing CaO/SiO2 ratio.

Mar 1, 2017

By Wei Lv, Xuewei Lv, Senwei Xuan, Chenguang Bai, Kai Tang

The contact angle between six iron ores and water were determined by the capillary pressure method with cyclohexane as the perfect wetting liquid. The factors influencing the contact angle were discussed, and a relationship between the content of oxy–hydroxides and the contact angle of iron ores was obtained. The results show that the ore F has the lowest contact angle but the ore D get the biggest, which are 32.09° and 78.16°, respectively. The volume fraction of oxy–hydroxides is linearly dependent on the contact angle. The contact angle decreased with increasing the volume fraction of Fe2O3*H2O.

Mar 1, 2017

By Helio Wiebeck, Vijay Rangari, Julyana Santana, Francisco Valenzuela-Díaz, Esperidiana Moura, Marcus Vinicius de S. Seixas

Closed-cell polyethylene (PE) foams have been extensively used in many applications such as packaging, transportation, sports, construction, and agriculture because of their variety of properties including light weight, chemical resistance, thermal and electrical insulation. The objective of this study is to evaluate the influence of electron-beamirradiation on the properties of LDPE/EPDMblend foams. The LDPE/EPDM blend (80/20 wt%) were prepared by melt extrusion, using a twin-screw extruder machine. The foam structure of LDPE/EPDM blends was obtained by melt extrusion process, using a special single screw for foaming with 1.5 wt% of foaming agent as blowing agent. The foam samples were irradiated by electron-beamat radiation dose of 25, 50, 75 and 100 kGy and submitted to heating in an oven at 100 °C. The specimen tests samples of irradiated and non-irradiated foams were submitted to mechanical tests, DSC, TG analysis and density measurement.

Mar 1, 2018

By Pedro Henrique L. M. Lopes, Édio Pereira Lima Jr., Fernanda Santos da Luz, Fábio de Oliveira Braga, Sergio Neves Monteiro

Several works have been dedicated to study the ballistic response of multilayered armor systems (MAS), including those using natural fiber composites as second layer. These composites disclosed good ballistic performance, having economic and environmental advantages. In the present work, the objective was to investigate the effect of areal densities of each MAS layer, in the overall performance of a MAS with an alumina ceramic front, a curaua fabric reinforced composite filling, and an aluminum alloy backing the target. Ballistic “backface signature” tests were conducted, varying the areal densities of the MAS layers according to a Box-Behnken design. The results showed a similar influence of the ceramic and aluminum layers in the MAS “backface signatures”, although deformation and failure mechanisms were significantly different. The composite also showed significant participation in the overall MAS performance. Since the composite is cheaper and lighter, a balance minimizing the other layers would be advantageous.

Mar 1, 2018

By Felipe P. D. Lopes, Caroline G. de Oliveira, Sergio N. Monteiro, Lucas A. Pontes, Janine F. de Deus

For decades, natural fibers have been studied as an economical and environmentally viable alternative to use instead of some types of synthetic fibers, for example fiberglass. To find the best way to make composites, the investigations shall be under various configurations, which is extremely important to understand the potentialities and facilities. To aim the comparison of impact performance of epoxy matrix composites reinforced with ramie fabric, the composites were produced by two different methodologies: under pressure and vacuum. The results show that the composites produced under pressure have greater resistance to both the Charpy and Izod Impact than under vacuum conditions.

Mar 1, 2018

By Zhenfeng Zhou, Qingguo Xue, Jingsong Wang, Yingli Liu, Yuanyuan Zhang, Hailong Huo

Coal burnout strongly depends on the residence time and dispersion of coal particles in the raceway region of a blast furnace. The residence time and dispersion of coal particles are directly related to the lance arrangement. In this work, a three dimensional model was developed to simulate the lance-blowpipe-tuyère-raceway region of a blast furnace. Double lance and eccentric configurations were considered. For the double lance, the double-lance and eccentric double-lance were considered. For the eccentric double lance, the effect of intersection angle of the two lances was investigated.

Mar 1, 2017