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By Nelson Severinghaus

Mineral fillers have been defined as inert materials that are included in a composition for some useful purpose. Because this definition and the scope of this review are not specific- indeed, exceptions abound-accurate total statistics are unavailable. One source estimates the total production in the United States in 1971 at 5 million tons valued at $200 million, averaging $40.00 per ton. Included are a broad group of minerals-asbestos, barite, bentonite, calcium carbonate, clays, diatomite, feldspar, micas, silica, talc. Additional references will be made to synthetic mineral-derived fillers such as aluminum hydrate, precipitated calcium carbonate, and pyrogenic and precipitated silicas and silicates. A section on related uses at the end of this chapter covers absorbents and filters. Mineral fillers can be included in compounds to accomplish a variety of final results. Hardness, brittleness, impact strength, compressive strength, softening point, fire resistance, surface smoothness, electrical conductivity, and a host of other physical characteristics may be modified by the inclusion of fillers. These effects are the result of properties of the fillers, including chemical activity, hardness, particle size, shape and distribution, surface structure, color, density, and refractive index. To facilitate an overview of the mineral filler industry, this chapter will review the general usage of fillers, the inherent characteristics that intensify their utilization, and similarly their manufactured characteristics. Major using industries will then be examined in detail. Specific information on deposits and processing for industrial minerals will be found in the appropriate commodity chapter. The chart in Table 1, updated from the 3rd edition of Industrial Rocks and Minerals, illustrates the major mineral fillers (both natural and manufactured) and their more important end uses.

Jan 1, 1975

By T. M. Tharp

Attempts to analyze the stability of slopes, foundations and underground openings in discontinuously jointed rock have generally assumed full joint continuity or ignored the role of stress concentration at the tips of discontinuous joints. The most common approach in rock slopes is to consider a failure plane consisting of coplanar, but discontinuous joints separated by intact rock. The intact rock is assumed to fail in shear as a MohrCoulomb material and to contribute a strength component proportional to the fraction of the failure plane that is intact rock (Jennings, 1970). An alternative approach by Stimpson (1978) applies Lajtai's (1969) theory for shear strength of discontinuously jointed rock masses to slopes. Lajtai allows tensile failure in the intact rock of a composite surface. This theory yields lower shear strength than that of Jennings (1970) except in the presence of high normal compression, however it also fails to account for the stress concentration at the tip of a discontinuous joint. For a given slope geometry, stresses increase with slope height, but in both of these models rock mass strength is independent of size. A fracture mechanics analysis shows that particularly for small slopes, rock mass strength decreases with size.A continuous stepped failure surface produced by propagation of preexisting joints may develop at lower shear stress than pre¬dicted by the Jennings (1970) or Lajtai (1969) models. This fracture mechanics model applied to slopes in competent rock is more realistic in its assumed failure mechanism, and for large slopes more conservative than the Jennings (1970) or Lajtai models (1969).

Jan 1, 1984

By P Mitchell, J Proffett, I Munajat

Batu Hijau is an island arc porphyry copper-gold deposit located in the southwest corner of Sumbawa Island in the Sunda-Banda archipelago of Indonesia. Southwest Sumbawa Island is underlain by Early Tertiary, low-K calc-alkaline to weakly alkaline volcanic and intrusive rocks. Within the mine area the oldest exposed rocks are medium- to thick-bedded, medium to coarse andesite volcanic lithic breccia, thin bedded, fine-grained volcaniclastic sandstones and mudstones and hypabyssal porphyritic andesite. In the eastern portion of the mine area there is a thick sequence of quartz diorite that postdates the andesites. A small stock of Equigranualar Quartz Diorite predates the Batu Hijau deposit and occupies the contact between the andesitic volcaniclastic sequence of rocks and the Porphyritic Quartz Diorite. Batu Hijau is a world-class copper-gold deposit that has a drill indicated mineable reserve of 914 million metric tonnes grading 0.525 per cent copper (10.58 billion pounds copper) and 0.403 g/t gold (11.8 million ounces gold). Mineralised material not in reserve accounts for an additional 580 million metric tonnes at 0.328 per cent Cu (4.19 billion pounds copper) and 0.171 g Au/T (3.19 million ounces gold), and including an oxide copper resource of 57 million tonnes at 0.37 per cent Cu and 0.12 g Au/T. Copper and gold mineralisation is directly related to quartz veining and wall rock alteration that developed with multiple tonalite porphyry intrusions. The tonalites were emplaced along the contact between the andesitic volcaniclastic rocks and quartz diorite intrusives. Copper and gold are zoned around the porphyry intrusions, which are designated by their contact-age relationships and other features as Old Tonalite, Intermediate Tonalite(s), and Young Tonalite(s). The Old Tonalite was the first copper-bearing intrusion, and although it is the smallest intrusion it has the highest quartz vein density, the strongest alteration and the highest grade. At least two tonalite porphyry intrusions followed the emplacement of the Old Tonalite. Each of these intrusions was associated with less quartz veining, weaker hydrothermal alteration and lower grade copper and gold than the previous intrusion. The intrusive cycle culminated with the emplacement of the Young Tonalite, which contains relatively few quartz veins, is weakly altered and mineralised. Hypogene hydrothermal alteration and sulphide mineralisation developed in five temporally and spatially overlapping stages. These stages consist of Early, Transitional, Late, Very Late, and I Zeolite alteration. Early alteration and sulphide mineralisation accompanied each tonalite porphyry intrusion, but with diminished intensity in each subsequent intrusion. Transitional and later stages of alteration and mineralisation postdate the tonalite porphyries and overprint Early stage alteration and mineralisation. Early alteration and mineralisation consisted of biotisation, secondary magnetite and plagioclase development, fine porphyry-style stockwork veining and ore mineralisation. Magnetite-biotite????quartz stringers and dark micaceous (biotite-sericite) veinlets were developed. The veinlets were accompanied by biotisation of magmatic mafic minerals and groundmass. Thin, irregular and discontinuous æAÆ type quartz veinlets and fine-grained chalcocite, digenite and bornite mineralisation accompanies the Early alteration. It is hypothesized that most of the copper mineralisation was originally deposited as bornite, digenite and chalcocite. Secondary plagioclase was added along the selvages of the early quartz veinlets. Early alteration is pervasive within and proximal to the tonalite porphyries. In the distal portions of the deposit, andalusite and anthophyllite formed at intermediate to shallow depths, and in the deeper portions of the deposit, respectively. The andalusite and anthophyllite probably developed at the same time as the early magnetite-biotite-quartz alteration in the core of the deposit. Transitional-age alteration consists of oligioclase/albite-sericite-chlorite- quartz-¦vermiculite and is associated with æBÆ quartz veins. Through-going planar æBÆ veins are thicker than æAÆ and æA-familyÆ veinlets and have chalcopyrite????bornite along vuggy centrelines and narrow oligioclase????albite alteration envelopes. Rare æCÆ chalcopyite¦quartz veinlets were also formed during Transitional alteration. During Transitional alteration early copper sulphide minerals (chalcocite, digenite and bornite) are converted to bornite and chalcopyrite. The majority of the copper (50 - 70 per cent) in the deposit is contained in ores in which chalcopyrite is the predominant sulphide. Late alteration consists of feldspar destruction and replacement by sericite and other minerals. The late alteration is accompanied by the development of æDÆ sulphide veinlets and veins. These veins consist of pyrite and quartz????chalcopyrite. Within the halos of the late pyritic veinlets biotite is replaced by sericite, quartz-sericite, quartz-andalusite, or quartz-pyrophyllite+kaolinite replace plagioclase, and magnetite is converted to specularite and/or pyrite. In the periphery of the deposit, the feldspar destructive alteration, together with outer zones of Transitional-age alteration, constitutes what is commonly referred to as a æpropylitic zoneÆ. Very Late hydrothermal alteration is also characterised by feldspar destruction, but differs from Late alteration in that feldspar is replaced by smectite in association with sericite and chlorite. Sulphide mineralisation in this stage consists of sphalerite, galena, tennantite, pyrite and chalcopyrite. The last stage or I Zeolite alteration consists of low-temperature, open space filling consisting of stilbite or laumontite¦calcite. Supergene oxidisation of the orebody extends to a maximum depth of 210m. Isolated deep oxidation occurs along open fracture zones to depths of ~400 metres along æDÆ vein filled fracture zones. Weak supergene copper enrichment occurs in a thin horizon (15 to 60 m thick) that blankets the top of the deposit. The main supergene copper mineral is secondary æsootyÆ chalcocite replacement of sulphide grains and as veins.

Jan 1, 1999

By M. L. Harris

In underground mines, coal dust explosions are prevented by the addition of rock dust sufficient to render the coal dust inert. The National Institute for Occupational Safety and Health (NIOSH) developed a hand-held instrument that uses optical reflectance to measure the explosibility of a rock dust and coal dust mixture. This instrument is called the Coal Dust Explosibility Meter (CDEM). In this study, NIOSH personnel accompanied Mine Safety and Health Administration (MSHA) inspectors on their routine band surveys in five underground coal mines in MSHA District 2 (Pennsylvania) and three underground coal mines in MSHA District 11 (Alabama). While underground, NIOSH personnel and MSHA inspectors used the CDEM to assess the explosibilities of the dust samples. The values of percent incombustible content (percent IC) determined by the CDEM agreed well with those obtained later by low-temperature ashing (LTA) in both MSHA and NIOSH laboratories. Further, the meter identified some samples as potentially explosible that LTA analysis had found to possess sufficient rock dust for inerting. The CDEM provides more information on the hazards in the mine. Rapid identification of areas with explosible dust mixtures using the CDEM allows for immediate intervention rather than a wait of several weeks for laboratory analysis.

Jan 1, 2008

By Jacques J. Eksteen

Any effort to improve the metallurgical control of industrial furnaces employed in the primary extraction of high carbon ferroalloys are bound to fail unless the variability of the melt is not fully accounted for. A number of sampling campaigns were performed on both 3phase AC submerged arc and single phase DC open arc furnaces at different smelter sites in South Africa where High Carbon Ferrochrome is produced. It was found that the heterogeneity between multiple samples during a single taps were much higher that for heterogeneity found within a sample. Moreover, this heterogeneity (as quantified by the relative standard deviation per tap) varied with the operating conditions of the furnace, the element monitored and the type of furnace. A relationship was found between the relative standard deviation of certain elements and the degree of subcooling of the melt.

Jan 1, 2006

The effect of microwave radiation on the processing of Palabora open pit ore has been investigated. Significant reductions in Bond work index are demonstrated for microwave treated samples. Reductions in work index were found to be sensitive to applied power level and method of application. After single stage magnetic separation tests, improvements in recovery of FeO were noted. However, these were curtailed by oxidation of the magnetite species as a result of continued heating. The effects of microwave radiation upon the recovery of copper after froth flotation were also quantified. Small initial increases in recovery of copper were note dafter microwave treatment. However, with prolonged exposure, recovery was found to decrease. Overall recovery of copper was not affected except for samples treated for extended duration. The influence of microwave treatment upon the conventional Palabora grinding circuit has been quantified with the use of USIMPAC software. Conclusions are made regarding the economics of microwave treatment for this ore. Keywords : Microwave; Grinding; Magnetic Separation; Flotation; Economic Analysis

Jan 1, 2000

By P. Kolodziejczyk

Mining seismicity can be harmful both under and on the surface. ? Tremors are not totally damaging, but destructive to buildings and infrastructure, especially in highly urbanized regions, such as Upper Silesia in Poland ? Destroy the social appreciation, trust and support for mining industry ? To prevent or reduce these effects, engineers and scientists develop methods allowing prediction of ground shaking intensity near buildings and various losses that can result from it Evaluation and prediction of mining tremor?s damaging influence on buildings is usually solved with two steps: ? Estimation of local ground shaking intensity (based on known attenuation relation) and classification into one of several predefined intensity intervals ? Apply supposed relation between the shaking intensity interval and qualitatively defined damaging effects to express predicted effects This makes a mixed quantitative/qualitative procedure, difficult to analyze or optimize

Aug 1, 2013

By Sidney Katell

Covering the period from January 1961 through December 1961, this report is a continuation of the series that began with the publication of Information Circular 7516 in October 1949. It is also the third report in the series to be prepared as a cooperative effort by the Bureau of Mines and the American Association of Cost Engineers. The cooperative agreement between the two groups provides for the publication of an annual cost bibliography with the work load involved in the preparation shared equally. The abstracted articles, concerned with all facets of cost engineering in the field of chemical and petroleum plants and related facilities, came from the following sources: 1. A.A.C.E. Bulletin. 2. Bureau of Mines Information Circulars. 3. Bureau of Mines Reports of Investigation. 4. Chemical Engineering. 5. Chemical Engineering Progress. 6. Chemical Week. 7. Coal Age. 8. Coal Utilization. 9. Cost Engineering. 10. Industrial and Engineering Chemistry. 11. Nucleonics 12. Oil and Gas Journal. 13. Petroleum Engineer for Management. 14. Petroleum Refiner. 15. World Oil.

Jan 1, 1962

By H W. Wu, D Humphreys

The structure of a comprehensive research project into mine fires study applying the Ventgraph mine fire simulation software, preplanning of escape scenarios and general interaction with rescue responses is outlined. The project has Australian Coal Association Research Program (ACARP) funding and also relies on substantial mining company site support. This practical input from mine operators is essential and allows the approach to be introduced in the most creditable way. The effort is built around the introduction of fire simulation computer software to the Australian mining industry and the consequent modelling of fire scenarios in selected different mine layouts. Application of the simulation software package to the changing mine layouts requires experience to achieve realistic outcomes. Most Australian mines of size currently use a ventilation network simulation program. Under the project a small subroutine has been written to transfer the input data from the existing mine ventilation network simulation program to æVentgraphÆ. This has been tested successfully. To understand fire simulation behaviour on the mine ventilation system, it is necessary to understood the possible effects of mine fires on various mine ventilation systems correctly first. Case studies demonstrating the possible effects of fires on some typical Australian coal mine ventilation circuits have been examined. The situation in which there is some gas make at the face and effects with fire have also been developed to emphasise how unstable and dangerous situations may arise. The primary objective of the part of the study described in this paper is to use mine fire simulation software to gain better understanding of how spontaneous combustion initiated fires can interact with the complex ventilation behaviour underground during a substantial fire. It focuses on the simulation of spontaneous combustion sourced heatings that develop into open fires. Further, it examines ventilation behaviour effects of spontaneous combustion initiated pillar fires and examines the difficulties these can be present if a ventilation reversal occurs. It also briefly examines simulation of use of the inertisation to assist in mine recovery. Mine fires are recognised across the world as a major hazard issue. New approaches allowing improvement in understanding their consequences have been developed as an aid in handling this complex area.

Jan 1, 2005

By Francisco Grimaldo

La minera de Cerro de Pasco cuenta con una mina polimetálica de plomo, zinc y plata con mineralogía compleja, cuyo yacimiento principal se desarrolla en los cuerpos mineralizados de Sílica-Pirita, generador de aguas ácidas. Sin embargo, las filtraciones, el minado y los minerales acumulados en stock piles de diferente composición mineralógica han generado aguas ácidas subterráneas y superficiales que se caracterizanpor su alto contenido de metales pesados (hierro y zinc). En ese sentido, el presente texto señala dos proyectos contenidos en el PAMA que buscan reducir el problema ambiental generado por las aguas ácidas y abastecer las necesidades de agua de sus procesos industriales. El primer proyecto comprende la separación de aguas neutras del interior de la mina subterránea, mientras que el segundo, la construcción de la planta de neutralización de alta densidad.

Jul 31, 2003

By R. H. Fernald, C. D. Smith

When the United States Geological Survey began operations at the coal-testing plant erected at the Louisiana Purchase Exposition at St. Louis, Mo., in 1904, it had already outlined a comprehensive plan for the systematic study of coals, lignites, and other mineral fuels with reference to their suitability for particular purposes and the methods by which they could be utilized most efficiently. Recognizing the need of information on the relative economy of producer gas as compared with steam for power purposes and the lack of comparable tests of American coals in the gas producer, the Geological Survey undertook investigations of the merits of different coals as producer fuel for the purpose of promoting efficiency in the utilization of the nation's fuel supplies. These investigations were carried on at St. Louis, Mo., and, later, at Norfolk, Va., and Pittsburg, Pa. The aet of Congress approved May 16, 1910, transferred the fueltesting work being carried on by the Geological Survey to the Bureau of Mines. This bureau is conducting producer-gas tests at P~ttsburg, Pa., and is publishing and distributing reports relating to all the fuel tests made by the Survey. These investigations into the possibility of generating producer gas in a commercial way for power purposes from the various fuels of the country have been associated with steaming, briquetting, coking, and other tests, all of which supplemented an examination into the nature, extent, and distribution of the fuels. The tests have all been made with carefully selected representative samples and carload lots of materials procured specially for the purpose by experienced collectors.

Jan 1, 1911

By W. Dan Hausel

More than 220,000 diamonds have been found in the United States that range from microdiamonds to 40.42 carats in weight (Table 1). Some reports suggest diamonds weighing more than 100 carats have also been found in this country, although these reports have not been verified. The source of most of the diamonds in the United States is a group of kimberlite pipes, dikes and blows in the Colorado-Wyoming State Line district and a group of lamproite pipes in the Murfreesburo, AR area. Other areas where diamonds have been found include the Great Lakes region, the Pacific Coast and the southern Appalachian Mountains. The latter two regions are generally not considered favorable for diamond deposits. This is based on exploration models. They suggest commercial diamond deposits will be restricted to kimberlites emplaced in Archean cratons and to lamproites emplaced in Proterozoic mobile belts accreted to the cratons.

Jan 1, 1995

By Craig M. Sams

"Variable speed mill popularity has grown during the last 10 years with almost every SAG mill fitted with a variable speed drive. In addition, many of today’s larger ball mills are running a variable speed drive for various reasons. In the past, motor suppliers, especially gearless drive suppliers, have considered mills as being an overpriced rotor. This has lead to mills demanding more torque than what a motor can generate. This paper identifies the reasoning of what has happened and how to mitigate the mismatch in the future. Technical and economical issues are discussed, allowing mill operators to make an informed decision of which path to take in deciding what motor to put on a mill.INTRODUCTIONIt has been generally accepted in the past that motor suppliers and specialists in engineering companies understand the workings of a SAG mill or a ball mill and although there is a fair knowledge within the industry, in regards to mill torque requirements, the advent of variable speed drives in ball mills has shown the writer that a complete understanding of the mill torque requirements are not fully understood.This paper will discuss two aspects of mill torque requirements, (operating torque at various charge levels and start up torque), and how it relates to specifying the proper motor torque requirements.MILL OPERATING TORQUEMill operating torque at a given charge level and density in a mill is essentially constant throughout the entire speed range. For the purpose of this paper, we will take a 38’x 22.5’, 20’ EGL, SAG mill and provide the power draw at variable speeds but fixed loading conditions.The power draw and mill torque of this mill at 8% ball charge and 28% total loading (Highlighted) is shown below as Figure 1, at variable speeds."

Jan 1, 2007

By D van der Wal, R Dobbe, K Moeller

"Ore mineralogy and texture are primary variables controlling mill recovery efficiency in flotation plants. However, tracking daily variations of key mineralogical characteristics such as species-by-species liberation is not possible with current on stream analysers and assay lab techniques. In addition, traditional plant mineralogical analysis limited by long data turn-around times from central analysis laboratories typically provides only a time-averaged view of mill performance, e.g. by means of monthly composite feed, con or tailings analysis.This paper presents the results of a development and first field test of an on-site Automated Mineralogy solution (MLA or QEMSCAN) with the specific goal of monitoring recovery variation, ore quality and flotation performance on a mineral species-by-species and day-by-day basis, from up to twelve million direct particle observations per month. The trial was performed at a Pb/Zn-Ag operation in the US from November 2012 to April 2013. The focus of the study was three-fold: to validate the robustness of equipment and operational procedures for daily use by mine site technicians at a remote mine site to develop a methodology to boil down hundred-thousands of Automated Mineralogy particle data from size-by-size con and tailings samples to a couple of numbers meaningful to chief metallurgists to monitor recovery trend changes and correlate these to changes in the feed properties and/or flotation efficiency.The study focused primarily on the Pb/Ag rougher-concentrator circuit. Ten polished blocks of two and three size fractions of con and tailings were prepared by mine site technicians during a daily twelve hour shift. Eight hours of daily measurement time by the instrument revealed an estimate of the dayÆs recovery performance, ore quality and flotation performance for Freibergite (Ag-species) and Galena (Pb-species), within 36 hours from initial sampling. Data quality was assessed by means of calculated versus measured assay reconciliation. Cumulative sum curves of recovery performance, ore quality and flotation performance reveal trend changes with a frequency of 1 to 4 weeks. These were correlated to cumulative sum curves of e.g. locked and slimed particle classes of the mineral species of interest, attempting to identify a possible root cause of recovery performance trend changes. Systematic over-grinding and flotation chemistry issues were the primary causes of below average plant operations during the trial.CITATION:van der Wal, D, Dobbe, R and Moeller, K, 2013. Development of an on-site mineralogy solution for metallurgists, in Proceedings MetPlant 2013, pp 126-132 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 15, 2013

By Flaviana Dias Rocha Pimenta

Com o objetivo de adequar a logística interna ás particularidades e variabilidade das demandas de movimentação interna de produto, a VBR (Vallourec Tubos do Brasil S.A) estudou em parceria com o operador logístico TRADIMAQ um novo modelo de equipamento que atendesse todas as regras internas de segurança e as diversas restrições em sua operação. O presente trabalho tem como objetivo apresentar as diferenças entre o modelo anterior utilizado para a movimentação interna e o atual modelo implementado no final de 2015, bem como todas as alterações necessárias entre o projeto conceitual e o equipamento em operação atualmente.

Aug 17, 2017

By S. -H. Chang, C. -I. Lee, Y. -K. Lee

Based on results from triaxial compressive tests, an experimental damage model to simulate post-peak behaviours as well as nonlinear behaviours before peak strength was developed. In order to consider pre-peak behaviours, variations of elastic constants at each damage level were regressed by functions of confining pressure. In addition, post-peak behaviours were simulated successfully by using Hoek-Brown constants. As results, the experimental model could predict nonlinear behaviours, peak strengths and stiffness changes observed in experiments. Basé sur des résultats des essais compressifs à trois axes, un modèle expérimental de dommages pour simuler des comportements de poteau-crête aussi bien que des comportements non-linéaires avant la force maximale a été développé. Afin de considérer des comportements de pré-crête, des variations des constantes élastiques à chaque niveau de dommages ont été régressées par des fonctions de pression d'emprisonnement. En outre, des comportements de poteau-crête ont été simulés avec succès en employant des constantes de Hoek-Brunes. Comme résultat, le modèle expérimental a pu prévoir des comportements non-linéaires, des forces maximales et des changements de riidité observés dans les expériences. Auf Basis der Ergebnisse des dreiaxialen Drucktests wurde das experimentelle Schadensmodell, das sowohl das nicht-lineare Verhalten vor der maximalen Stärke als auch das Verhalten nach der maximalen Stärke simulieren kann, entwickelt. Um das Verhalten vor der maximalen Stärke zu berücksichtigen, wurden die Veränderungen der elastischen Konstante bei dem jeweiligen Schadensniveau durch die Funktionen des begrenzten Drucks zurückgegangen. Außerdem wurde das Verhalten nach der maximalen Stärke unter Benutzung von Hoek-Brown Konstanten erfolgreich simuliert. Schließlich konnte das experimentelle Modell das nicht-lineare Verhalten, die maximale Stärke und die Veränderungen bezüglich der Steifigkeit während der Experimente voraussehen.

Jan 1, 2003

By Lucas Monteiro Corrêa e Lopes, Carolina Carvalho Nunes, Nathalia Luiza Nascimento de Carvalho

The characteristics of each ore make it impossible to predict the quality of a flotation concentrate without exploratory tests. The research begins with laboratory batch tests, and then, after advances in the determination of process conditions, the complexity of the tests increases in order to evaluate new parameters. The closed cycle test (LCT) simulate circuits with load recirculation and the greatest difficulty of this test is to stabilize the circuit and achieve equilibrium. Depending on mass availability, the types of tests that offer the highest reliability and informations about flotation in an ongoing process are mini-scale or pilot-scale tests. This work aimed to compare the results of the flotation tests in three scales (batch test, LCT and mini pilot) for the Bonsucesso ore, a new deposit, owned by Nexa Resources, that has sphalerite, zinc ore, and galena, lead ore. In the open flotation circuit of galena was obtained 27.57% content with 26.70% recovery, in the LCT test the content was 31.54% with 64.64% recovery and in the mini pilot reached 51.22 % content with 65.51% recovery. In the open sphalerite flotation the zinc content was 55.51% with 77.35% recovery, in the LCT test the zinc content was 56.71% with 84.42% of recovery and in the mini pilot of 50.02% content with 94.54% recovery.

Oct 3, 2019

By Steve Kral

Borates are minerals that contain boron. Trace amounts exist in rocks, soil, water and people. Boron-containing ores are rare and U.S. Borax, a subsidiary of Rio Tinto Borax, controls one of the world’s two world-class borate deposits. Through its global systems of mines, refineries, ports, sales offices and distribution centers, the company supplies nearly 45 percent of the world’s demand for borates. Borax has been mining borates in California for more than a century. This year the company celebrated 131 years of continuous business in the Golden State and 76 years at its operations in Boron, the site of California’s largest openpit mine. It also has mines and refineries in Argentina, refineries and ship-ping facilities in Europe and technical staff in the United States, North and South America, Europe and Asia Pacific. So, with the 130±years of borate mining and processing experience behind it as well as its global marketing and distribution centers, there is very little that Borax does not know about borates.

Jan 1, 2003

By C. A. Young, J. D. Miller

The surface chemistry of the calcite/oleate flotation system was examined by in-situ FT-NIR/IRS. Spectra of combination and overtone bands of aliphatic stretching vibrations revealed gauche/trans conformational changes that occurred solely as a function of temperature. The conformational changes were attributed to the simple "melting" behavior associated with phase transitions. It was concluded that chemisorbed oleate at calcite surfaces is gel-like at temperatures below 22oC, resembles a coagel between 22oC and 31oC, and becomes micelle-like at temperatures above 31oC. By comparison, chemisorbed oleate at fluorite surfaces also undergoes these phase transitions but is additionally dependent on adsorption density. The conformational changes were observed at high chemisorption densities (> 2.0x10-10 mol/cm2) and attributed to molecular forces, primarily van der Waal's interactive forces, among neighboring chemisorbed oleate molecules. Similar analysis of in-situ FT-NIR/IRS spectra of surface-precipitated calcium dioleate at calcite surfaces did not exhibit this behavior thereby confirming that surface-precipitated calcium dioleate remains in an all-trans conformation. The results help explain why surface polymerization is not observed at calcite surfaces but is observed at fluorite surfaces.

Jan 1, 2002

By Timothy J. Myers

Expansion and the economic growth in the southwestern region of Missouri necessitated the expansion of State Route 249 and the construction of a new interchange to provide service to the Joplin, Missouri area. The project is located above a former lead and zinc mine in Jasper County, Missouri and includes a five bridge interchange connecting State Route 249 and US Route 171. The variable subsurface conditions, both natural and manmade, prompted the design team to use ground improvement via grouting and small diameter micropiles to provide support for several of the bridge foundations on the project. The scope of work included mine shaft closures, 56,000 ft of overburden and rock drilling, 11,139 ft of micropiles, 524 cy of balanced/stabilized high mobility grouts, and over 8,700 cy of low mobility grout. The selection of the grout used was based on the actual subsurface conditions. Low mobility grout (LMG) was used in voided conditions and for closure of the mine shafts encountered during the excavation. High mobility grout (HMG) was used in fractured rock with the goal of improving the mechanical properties of the rock underneath the future bridge footings and controlling grout volumes during micropile installation. The split spacing method was utilized for both LMG and HMG holes. Geology of the project site subsurface consisted of extremely variable bedrock with strong to very strong limestone, chert, breccia, extremely weak shale, and weak to strong sandstone. Previous activities associated with the mining disturbance (such as partial filled vertical mine shafts, shallow and deep mine horizons, modified hydrology including artesian conditions) further complicates the site subsurface conditions. Real time monitoring and recording of all drilling and grouting parameters was conducted to assist in the evaluation of in-situ geological properties of the site in order to modify the ground improvement and micropile program as necessary. This paper will discuss the design and execution of the ground improvement and micropile program. The project is an excellent example of the use of multiple ground improvement and foundation support techniques combined with real time data analysis to provide a foundation support solution for a complex geological environment.

Jan 1, 2009