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By Herbert L. Lines

This paper is one of a series on mining and milling methods and costs published by the Bureau of Mines. The Ash Peak mine of the Veta Mines, Inc., Duncan, Ariz., is of particular interest in that the only metal of commercial value in the ore is silver. The silver is concentrated by flotation; the concentrate is shipped to a smelter for treatment.

Jan 1, 1940

By Verônica Scarpini Candido

O uso cada vez mais frequente do poli metacrilato de metila (PMMA), muitas vezes em substituição ao vidro temperado, se deve a sua alta rigidez, praticidade, leveza e transparência. No entanto, as normas de fabricação atuais na indústria de polímeros recomendam testes específicos nesses materiais. O presente estudo tem o objetivo de testar mecanicamente as propriedades do material Polimetacrilato de Metila (PMMA) em condições que simulem um ambiente muito mais agressivo do que o usual. Para tanto foram realizados testes de espectroscopia na região do infravermelho (FTIR), análise termogravimétrica (TGA), testes de tração e impacto Izod, e análise por Microscopia Eletrônica de Varredura (MEV). Os resultados revelaram que o Polimetacrilato de metila (PMMA) manteve suas propriedades mecânicas em tração até a temperatura de 105°C. No que se refere à resistência ao impacto, a temperatura influenciou negativamente no desempenho desse polímero.

Oct 30, 2017

By Xueyuan Nie, Xuezhi Zhang, Henry Hu, Shen Xinwei, Jimi Tjong, Li Fang

With the demand for weight reduction in vehicles and airplanes, researchers have shown great interested in casting wrought aluminum alloy 7075 because of its potential advantages such as high strength-to-density ratio and stress-reduction capabilities. It is therefore essential to conduct a fundamental investigation on solidification behavior and grain microstructure of alloy 7075. In this study, a commercially-available wrought aluminum alloy 7075 was used to study the solidification behavior of alloy 7075. A thermal analysis was performed based on the cooling curve and its corresponding first and second derivative curves. The nucleation of the primary a-Al phase and eutectic phases were analyzed. The comparison between the microstructures of the wrought and cast 7075 alloys shows that coarse microstructure and porosity are present in the cast alloy. The techniques for grain refinement in casting, such as the addition of the nucleating particles and applied pressure, should be employed to reduce the dendrite arm spacing and the porosity.

Jan 1, 2015

By Fumito Tanaka

The Mitsubishi process is the sole pyrometallurgical process for the continuous production of blister copper from Copper concentrates and has been successfully operated around the world. The development of calcium ferrite slag (CaO-FeOx-Cu10), the so-called "C-slag", has enabled continuous converting from matte to blister copper in the commercial scale operations. Commercial interests in the slag led to many papers over the CaO-FeOx slag. However, Cu2O bearing slag has not been studied well due to experimental difficulties. The authors have quantified the thermodynamic properties of the CaO-FeOX-Cu2O system. The results have been utilized to analyze various issues related to the converting furnace, such as the magnetite precipitation from the slag or from blister copper and to develop better controlling criteria for the continuous converting operation. -

Jan 1, 2003

By J. T. Liu, G. H. Han, W. C. Chai, Y. F. Huang

"In beneficiation process, metal ions could adsorb onto clay mineral surfaces or interact with flotation chemicals, and then result in the flotation behavior changing of desired minerals. Al(III) is the dominating ion existing in the bauxite flotation system. In this research, the adsorption behaviors of Al(III) on two silicate clay minerals (including bentonite and kaolin) were investigated by means of UV-Vis spectra, zeta potential testing and scanning electron micrograph analysis. The adsorption experiment results show that the adsorption capacity of clays for Al(III) ions increases with the initial Al(III) concentration, contact time and solution pH. There are some different adsorption behaviours for two clays. Increasing the clay concentration decreases the adsorption capacity of bentonite, while increases first then decreases for kaolin. Higher temperature favours the adsorption of Al(III) on bentonite but goes against for kaolin. The adsorption capacities of bentonite and kaolin for Al(III) respectively reach 12.48 and 0.875 mg/g at initial solution pH 5. Zeta potential results show that the adsorption of Al(III) on two clays is characterized by electrostatic attraction mechanism.INTRODUCTIONIn beneficiation process, there is inevitably a wide variety of metal ions generated from mineral crushing, mineral dissolution and water chemistry conditions. Metal ions adsorb on the mineral surfaces or interact with the beneficiation agents, affecting the flotation efficiency of desired minerals (DiFeo et al., 2001; Parolis et al., 2008; Shackleton et al., 2012; Shengo et al., 2014). Therefore, it is necessary to have a detailed investigation on the adsorption behaviour of metal ions on clay minerals.Having good ion exchange capacity and negative surface charge, the clay minerals could take up various metal ions from the mineral-water system. Bentonite and kaolin are very common aluminosilicate clays in the mineral processing system. These two clays both hold a permanent negative charge, =X- on the basal surfaces, and a smaller variable charge, =SiOH on the mineral edges (Gu & Evans, 2008; (Gu et al., 2010). Adsorption experiments are usually used to study the adsorption affinity of metal ions for clay minerals (Sen & Bhattacharyya, 2012). The adsorption of Zn(II), Cu(II) and Pb(II) onto natural bentonite showed that the adsorption amounts of metal ions increase with contact time, solution pH and metal ion concentration, but decreases with adsorbent concentration and system temperature (Sen & Gomez, 2011; Melichova & Hromada, 2013). Cr(III) adsorption on bentonite was significantly pH dependent. The adsorption process followed pseudo-second-order model and the equilibrium adsorption was consistent with Freundlich isotherm (Lollino et al., 2015). The adsorption behaviours of Pb(II), Cd(II), Ni(II) and Cu(II) onto kaolin indicated that increasing pH favoured the adsorption of metal ions (Jiang et al., 2010). The adsorption of Cd(II), Cu(II), Pb(II) and Zn(II) onto kaolin showed that an ion-exchange reaction occurred at pH<7.0 and inner-sphere surface complexes were prone to form at higher pH (Srivastava et al., 2005)."

Jan 1, 2016

By K. S. Raja, B. McNall, B. Pesic

"High-level radioactive wastes are stored in large underground storage tanks made of low-carbon steel. The wastes consist of concentrated solutions of sodium nitrate (NaNO3) and sodium hydroxide (NaOH), and the radionuclides 137Cs, 99Tc, and 90Sr. The corroding steel microenvironment may produce localized reducing or oxidizing conditions that affect the solubilities of the species such as Tc(VII) and Tc(IV), which in turn modifies the kinetics of corrosion of the storage tank. To understand the influence of technetate ions on the corrosion of steel, electrochemical polarization studies of A 537 steel samples were carried out in 1 M NaNO3 + 0 .05 M S r(NO3)2 + 0.1 M NaOH with and without addition of HReO4 at different temperatures (24 – 85 °C). The concentration of HReO4 was varied from 0.014 – 0.04 M.INTRODUCTIONAqueous processing of spent nuclear materials generates a large amount of high-level radioactive wastes. The wastes are primarily salt solutions of sodium hydroxide and sodium nitrate which also contain fission products such as 137Cs, 99Tc, and 90Sr. Among the high level radioactive fission products, Tc-99 is of great importance because of its high concentration, long half-life (2.1 x 105 years), high solubility in geologic waters as technetate, and rapid diffusivity through the geologic systems. The solubility of technetate ions varies depending on the oxidizing conditions prevailing in the storage containers. High level radioactive wastes are stored in single shell or double shell tanks made of low carbon steels such as ASTM type A15, A516-70 and A537. Most of the available literature on corrosion of steel in simulated radio active waste environments pertains to nitrate induced stress corrosion cracking (Subramanian & Mickalonis, 2005). The corroding steel microenvironment may produce localized reducing or oxidizing conditions that affect the solubilities of the species such as Tc(VII) and Tc(IV). Corrosion of steel and formation of Fe(II) and Fe(III) will affect adsorption and reduction of Tc species. The radioactive species can irreversibly be sorbed on the steel surface by oxidation of Fe(II) to more stable Fe(III) and fixed as less soluble Tc(IV)/Fe(III). The solubility of Tc species is also affected by other factors such as dissolved oxygen, local pH, temperature etc. How the corrosion behavior of steel will be affected in the presence of Tc species is not clearly understood.Cartledge (Cartledge, 1960) demonstrated that passivation of iron can be achieved in the presence of oxygen along with suitable inhibitor ions/molecules of the general formula XO4 n-, such as pertechnetate (TcO4 -). The pertechnetate ion is univalent. Since it is derived from a strong acid, no buffering action can be expected from this ion. The redox potential of the reaction (1) is 0.738 VSHE (Pourbaix, 1974)."

Jan 1, 2012

Stawell Gold Mines Pty Ltd operates two underground decline mines within the township of Stawell. An active exploration program and commitment by owners to improving the ore reserves has led to an improved mine life and reduced operating costs since the purchase of the operation by Mining Project Investors and Pittston Mineral Ventures in late-1992. Over the past six years of operation a cumulative 1 150 000 ounces of gold have been added to the mineral inventory. An improved geological understanding of the orebody has evolved over time increasing the ore reserves and allowing the development of long-term plans for the mines future. This has enabled important capital decisions to be made providing the impetus for improved productivity and thereby reduced operating costs. Co-operative mine planning and mine geology utilising best practice geological systems have enabled the effective extraction of a structurally complex and mineralogically varied deposit within a rural Victorian township. Detailed metallurgical research has improved the function of an aged and poorly designed circuit to boost the mill capacity whilst also improving the metallurgical recovery. The combination of metallurgical expertise and an understanding of the geological setting enable an effective control of metallurgical recovery.

Jan 1, 2000

Constraints on the mineral industry are best treated as issues that have to be understood and managed in partnership rather than in conflict with communities. The Zapopan development at Mt Todd in Australia and the Martha Hill development at Waihi in New Zealand are but two of many recent successful examples at the local level. However, at the national level, the issues are more complex and more difficult to resolve because the most influential stakeholders are now the urban electorates and governments defer to their perceptions when making decisions and policy.

Jan 1, 1995

After considerable input from the mining industry, the Canadian Securities Administrators (CSA) finalised National Instrument 43-101: Standards of Disclosure for Mineral Projects. This Instrument, which became law across Canada on 1 February 2001, applies to all technical public disclosure on mineral projects and requires all technical disclosure to be based on the work of a æqualified personÆ (QP). While the QP is quite similar to the Competent Person in Australia there are important differences when it comes to all disclosure. This paper will summarise the main areas in which the Instrument introduces major changes to Canadian disclosure standards on mineral projects including the role and responsibility of the qualified person; the increased requirements to file technical reports; the incorporation by reference of the October 2000 CIM definitions of resources and reserves and additional rules governing written disclosure of scientific and technical information. In October 2001, eight months after the implementation of NI 43-101, the CSA compiled a list of frequently asked questions (FAQs) and CSA responses to assist mining industry participants and their advisors in understanding and applying NI-43-101. This document has been well received by industry. The CSA plans to update the FAQs when further guidance is requested. Two industry committees have been established to provide the CSA with technical advice on the application of NI 43-101. As recommended by the Ontario Securities Commission/Toronto Stock Exchange Mining Standards Task Force, the CSA has established an external industry advisory committee û the Mining Technical Advisory and Monitoring Committee (MTAMC) û to monitor the application of NI 43-101 and advise the CSA on industry and professional developments. The role of the CSA-Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Working Committee on Reserves and Resources is to ensure that the future changes and updates to the CIM Standards can be efficiently and effectively incorporated in NI 43-101. During this first year, the Canadian securities regulators have seen an improvement in the quality of disclosure on mineral projects, which will increase investor confidence in the industry.

Jan 1, 2002

By Laffin N. W

Invariably when a new plant is cammissioned operations personnel on takeover look at ways and means of reducing certain restrictions and improving process conditions. These improvements are generally of a mechanical/engineering nature with minor metallurgical alterations to fine tune and maximise recovery. Most operations are continually reviewing and updating existing equipment and equipment spares to gain the maximum performance hereby reducing operating costs. Design of current carbon-in-pulp/carbon- in-leach (CIP/CIL) plants has evolved to such a high degree that many of the medium sized plants can have a "blue printed" design from one to the next if the same engineering designer is used.

Jan 1, 1989

By G. Sachs

THE iron-rich iron-nickel alloys have at-tracted considerable academic interest in recent years. The carbon-free alloys are of minor practical importance, but they are Atomic per cent nickel FIG. I. FIG. 2. FIG, I.-HONDA&apos;S AND MERICA&apos;s IRON-NICKEL DIAGRAM, FIG. 2.-MARSH&apos;S IRON-NICKEL CONSTITU-TIONAL DIAGRAM. the base of many alloys with various out-standing properties. The iron-nickel alloys, therefore, have been investigated exten-sively regarding both their structures and their properties. The researches on these alloys up to 1938 have been collected and critically reviewed by J. S. Marsh,1 and will be discussed in some detail in the sec-tions of this paper dealing with specific subjects. These numerous investigations have not succeeded in establishing the equilibrium conditions in this system. Alloys containing more than a certain amount of nickel (8 to10 per cent Ni) undergo the allotropic transformation extremely sluggishly, both on heating and cooling, showing a large hysteresis,2 which is not dependent upon

Jan 1, 1940

By Minna Rämä

Iron containing leach residues like jarosite and goethite from electrolytic zinc production contain many valuable metals and harmful substances. These metals and substances should be removed in order to obtain an acceptable, stable and reusable product, and maximize economic feasibility as well as minimize environmental footprint. In this work, the processing of jarosite leach residue was studied in laboratory scale experiments under oxidizing and reducing conditions at high temperatures. First, the pretreated material was melted and oxidized to produce a melt of metal oxides. Second, the oxide melt was reduced in CO–CO2 atmosphere. Target after the reduction step was to obtain a clean slag and a liquid metal or speiss phase that collects the valuable metals, such as silver. The kinetics of the thermal processing were studied for determining optimal times and conditions for the aforementioned process steps. The preliminary results show that the process is thermodynamically feasible, and the desired phases can be obtained in the experimental conditions investigated.

By Wei Luo

Nickeliferous laterites were characterized by particle size analysis, X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDX), Fourier transform infrared (FTIR) spectroscopy and thermal analysis. Results showed that the laterites consist mainly of nickel-substituted lizardite with cobble-like morphology and traces amounts of magnetite and phlogopite. As fluoride ions can react with silicon in the lizardite crystal structure and form metal-fluoride complexes, as well as increase the equilibrium constant of the lizardite dissolution in acid solution dramatically, the addition of minor fluoride salts (0.2wt.% NaF) gave a markedly enhanced metal extraction rate (Ni 81.7% and Co 52.3%) under the experi-mental conditions of particle size d50= 25 µm, 10% (v/v) H2SO4, reaction time 2 h, reaction temperature 90°C, liquid-to-solid ratio 3 mL g-1 and stirring at 500 rpm compared with H2SO4 alone (Ni 69.6% and Co 30.8%).

Jan 1, 2010

By Carl F. Wingquist

In support of Bureau of Mines studies of thermal fragmentation of rock, the elastic moduli of four types of rock were measured at temperatures ranging from room temperature up to 1,500° F (1,089° K). The sonic method was employed to determine the resonant frequencies of the rock specimens and from these frequencies, the elastic moduli were calculated. Data for Young&apos;s modulus, shear modulus, and Poisson&apos;s ratio are given as a function of temperature for Dresser basalt, Reserve taconite, Jasper quartzite, and Charcoal granite. Young&apos;s modulus and the shear modulus decreased with increasing temperature up to about 1,200° F and then became relatively insensitive to temperatures from 1,200° to 1,500° F.

Jan 1, 1969

By Robert S. Shoemaker

The development of a metallurgical project is a business venture rather than a technical exercise, and its real objective is to obtain the maximum return on investment consistent with the limitations imposed by company policy and the requirements of society. Demand for profits is the driving force for technical advances and naturally leads to improvements in processes, equipment and plant designs. In the mineral dressing field there have been virtually no new processes developed since the introduction of flotation, and the steady erosion of profits by inflation has been offset only by increasing equipment size. Unfortunately, in recent years, plant designers have not always utilized the largest equipment or the opportunities for functional and economic design presented by the development of larger equipment. Lower cost plants can be developed providing that unrealistic restraints arising from the prejudice of past practices are avoided. As an illustration of this premise, three different approaches were taken toward the design of a clearly delineated but hypothetical copper concentrator of 20, 000 tons per day capacity. While the same flowsheet was used in each case, designs were produced for a conventional plant, an alternate using the largest available equipment, and a third scheme utilizing large equipment and the most functional design which could be developed, including features derived from many plants in many different industries. Capital costs were developed for the three separate designs based on a location in the southwestern United States. Ancillary facilities were identical in each case and included a mine truck shop, a maintenance shop, a general office, and a nominal starter dam for tailings disposal within 5000 feet of the plant. Water supply within 1000 feet of the plant, and power furnished to the property boundary has been assumed in each case. The flowsheet of the three plants is shown in Figure 1 and represents the treatment of a typical sulfide copper ore by three- stage crushing followed by single-stage ball milling. Concentration is by flotation roughing and scavenging followed by regrinding of the concentrates and two stages of cleaning.

Jan 1, 1971

By C. Ortuglio

The Bureau of Mines developed equations to determine the relationship of yields and products obtained from BM-AGA carbonization in 13-and l8-inch-diameter retorts. The developed equations indicate that results of carbonization in l8-inch-diameter retorts can be predicted from results obtained with l3-inch-diameter retorts.

Jan 1, 1966

By W. E. Cooper

The International Intercalibration and Intercomparison Program (HIP), consisting of several selected laboratories from four countries, held a radon progeny intercomparison measurement at the U.S. Bureau of Mines experimental Twilight Mine on September 12-14, 1988. Grab samples were taken at four different conditions of low and high radon progeny and condensation nuclei concentrations, respectively. The results showed good agreement among all seven participants. The coefficient of variation of all measurements was 4.7%; after minor corrections for flows and some systematic biases, it was reduced to 3.2%.

Jan 1, 1990

By R. David Prengaman

During the past several years a new insoluble lead anode has been developed for copper electrowinning. The new anode consists of a rolled lead-calcium-tin alloy sheet attached to a slotted copper bus bar by a soldering process which produces a complete metallurgical bond between bar and sheet. The metallurgical bond greatly reduces the resistance between the bus bar and the lead sheet and the high conductivity does not deteriorate during the life of the anode. The rolled anode thins uniformly and does not suffer preferential grain boundary or internal corrosion commonly seen in cast anodes. The lead-calcium alloy containing a high tin content corrodes slowly because the rolling process produces a uniform, fine grained structure. The wrought product is very strong and ductile; and contains no internal defects, segregation, cracks, or pores which can reduce the life of the anode. Because the anodes corrode uniformly, a high percentage of the anode thickness can be utilized thus extending the life of the wrought anodes. The anode alloy composition which is stable only in wrought form, produces exceptional resistance to passivation during current interruptions. First introduced into liberator cells, the new electrowinning anodes have been specified as the anodes of choice for every new SX-EW tankhouse constructed in the last two years. This paper describes the new anode, its method of construction, service history, and how it differs from present copper electrowinning anodes.

Jan 1, 1987

By Dao Dac Tao

The Vietnam coal industry in recent years has achieved the rapid growth. However, in the process of industrialization and modernization of the country, the demand for coal for energy is constantly increasing. This paper presents the Vietnam coal industry in the last stage: the opportunities and challenges facing the coal industry as it strives to become modern, highly effective and capable of meeting the demands of national energy security, all in harmony with socio-economic and environmental needs.

Aug 1, 2013

By F. S. Niu

With the feature of finely-dissemination particle and complex mineral composition, oolitic hematite is considered to be the ore dressing difficult problem in the world. Series research on refractory oolitic hematite in Zhangjiakou Area are introduced as following: ore properties?technology mineralogy and mineral processing technology. The survey shows: with the fine grinding of the hematite to a fineness of -0.076mm 95%, obtaining iron concentrates grading 62.74% Fe at the recovery of 46.80% by high intensity magnetic separation- reverse flotation flowsheet; under the three stages intensity magnetic separation,four stages grinding and four stages gravity separation, getting the iron concentrates grading 61.09% Fe at the recovery of 45% using high intensity magnetic separation- gravity separation flowsheet; with roasting temperature of 800°C, time for 75~90min and ore-coal ratio of 11, gaining the iron concentrates assaying 62.74% Fe at the recovery of 87% by roasting- magnetic separation flowsheet. At present, this research is still doing for the target of raising the concentration recovery on the base of high grade concentrate. It is in the hope of fully utilizing the existing hematite resources in Zhangjiakou

Jan 1, 2014