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By J. Kendall Hales

Jan 1, 2005

By H. E. Hilliard

The Bureau of Mines investigated hydrometallurgical procedures for concentrating precious metals from a mechanically processed metal fraction of obsolete military electronic scrap. Feed material for the leaching procedures described in this report was the high-tension-separated metal concentrate obtained as a fraction from mechanically processing partially stripped electronic units. Initial pretreatment with a 20-wt-pct-NaOH solution solubilized most of the aluminum. After washing, the resulting residue was incinerated to destroy any organics attached to metal particles. The incinerated residue was leached with 20-vol-pct H2S04 solution using two methods, countercurrent pressure and ultrasonic-aided leaching to solubilize the base metals, predominantly copper. Silver was recovered from the base metal leach residue using 50-vol-pct HN03, and gold contaminated with several percent palladium was recovered from the silver leach residue using aqua regia. The impure silver and gold plus palladium products represent about 1.5 wt pct of the high-tension-separated metal concentrate. Included is a three-step process evaluation study of mechanical processing of general electronic scrap and two hydrometallurgical procedures for leaching high-tension-separated metallic concentrates obtained from the mechanical processing step. Process evaluation concluded that only mechanical processing is economically viable.

Jan 1, 1985

Any Australian who knows of the poverty of the early settlers in the first few years following the arrival of Captain Arthur Phillip with his "first fleet" at Botany Bay must feel proud of the progress that has been made in the 174 years that have elapsed since that momentous occasionGFor all its attractive appearance as reported by Captain Cook and Sir Joseph Banks, the shores of Botany Bay and of Port Jackson proved most ,inhospitable, and the accessible country surrounding them anything but suitable for sustaining the life of the small settlement. It is well known that during the first 15 or 20 years the hardy colonists and un-tfortunate convicts were close to starvation on several occasions and were only saved by the arrival of supply ships, which were dependent on the vagaries of wind and current, and the hazards of the uncharted seas they had to -navigate-.When Australia was little more than a miserable penal settlement, Great Britain was one of the great-powers of the world, and the U,.S.A. was an independent nation with a growing degree of prosperity that even then gave promise of its mighty awakening to become, as it has, a e.olossus of industry and commerce,-and the. leader in living standards of the world to-day.Australia, from such a shaky, and comparatively recent start, has risen to a position in which its living standards rank very high in comparison with those of most of the nations of Europe and America. Exact com-parisons are hard to fix because of the wide variety of factors involved .but the Institute of Pab?Lic Affairs .(Victoria) places Australia fifthin the world, excelled only by the U.S.A., Canada, Sweden and Switzerland. The next best after Australia are the United Kingdom, West Germany and France.How we achieved such a high standard of living is a vast subject for study but some of the economic aspects of our climb from abject poverty to a position of near affluence can readily be identified.

Jan 1, 1962

By Lu Peiyan

A computation model of soil-pile (wall) interaction under lateral loading is presented in this paper. The model has been applied to some engineering projects, and the comparison between computation result and measured result shows good agreement, so the model is proved to be correct and practical.

Jan 1, 1991

By J. Ling, L. Racine, P. Cousin, A. R. Laplante

"The problem of gold recovery by gravity from high density gangues is first discussed from a fundamental perspective. Three potential difficulties are presented: poor liberation and fine gold particle size, concentrate bed erosion by coarse dense particles, and slow percolation of gold particle through the high density gangue bed. Two case studies are presented to illustrate the impact of these three problems on circuit performance and the feasibility of gravity recovery. It is concluded that careful testing can determine the scope of the first problem and feed preparation can limit the extent of the second. The third problem is clearly the most serious and results in lower gravity recoverable gold recoveries than would be achieved with the same recovery effort on a low density gangue application.IntroductionSince the commercialisation of the Knelson Concentrator in 1980, gold gravity recovery has experienced a surge in interest, in Canada and the United States first, then Australia, Zimbabwe and Russia, and finally worldwide. Table I details number of units sold in various countries, which corresponds approximately to their importance as gold producers 1. Exceptions. such as the low rank of South Africa or the importance of Zimbabwe, despite the much higher gold throughput of the former, are generally the result of differences in the effectiveness of the local marketing strategies, as well as a reflection of the ""philosophy of recovery"" prevalent in the country.The impact of the Knelson has not been felt equally in all plants. Typically, a highly successful application falls into the following categories: (a) alluvial or hard rock recovery for which gravity is the sole recovery method, (b) hard-rock free gold milling with ores which have a very high gravity-recoverable gold (GRG) content, (c) low grade sulphide copper-gold ores which include flotation ahead of cyanidation and (d) free-milling gold ores ahead of Other applications can be successful, but are not as common. The ""explosion"" of centrifuge concentration, of which the Knelson is the most successful but by no means the sole model, has created a certain euphoria which can be summarized as ""gravity recovery will improve the profitability of gold milling, no matter what."" This presentation is about applications that are not so successful, or even downright unsuccessful. The rationale is not to down-play gold gravity recovery, but to set it in its rightful position: metallurgically, it is not appropriate all of the times; it can become inappropriate if poorly designed; and it can be metallurgically possible but economically unjustifiable. In this paper, this will be illustrated and explained rather than demonstrated, with the use of both industrial plant surveys and laboratory test work. Alternate gravity approaches will be suggested."

Jan 1, 1997

By N. Som

The pile capacity in cohesive and granular soils depends on a number of parameters. The values of these parameters as recommended by Indian Standard Code of Practice vary over wide ranges. A designer often finds it difficult to select appropriate values of these parameters for realistic estimate of a pile capacity. The present paper makes a critical review of the values of the parameters given in Indian Standard Code of Practice and suggests a realistic approach to selecting them in the light of recent research.

Jan 1, 1996

In early 1970, General Mills Chemicals, Inc. announced the availability of en improved liquid ion exchange reagent, LIX® 64N, for the recovery of copper from various solutions, such as dump leach liquors. LIX 64N has been shown to be a considerable advance over LIX 64, and is presently in use in three commercial plants. Results have been very gratifying. For example, one of the plants was designed for operational production of 40,000 pounds copper per day, and in fact reached this output within the third week following startup of the plant. In addition to the operating plants, another is scheduled to come on stream this month with L D( 64N being used to extract and recover both copper and nickel. The chemical properties and operating characteristics of this reagent have been fully described in a previous paper. 1 LIX 64N is quite an effective and selective extractint for copper, even with copper contents as high as 15 g/l, but the reagent is somewhat limited in pH range, and loses some of its extraction efficiency as the pH drops below 0.8. Liquors derived from vat leaching, electrolytic tankhouae bleed streams, or some of the new leach schemes derived to solubilize copper from sulfide concentrates are examples of the liquors that present major problems when treated via liquid ion exchange. LIX 64N could extract some of the copper from such streams, but recovery was limited to about 75 percent. Also, in some parts of the world there are streams which are relatively low in copper (-5 g/l) but which are very high in acid (25-50 g/1 H2SO4). Again, LIX 64N can attain only about 75 percent recovery from such streams. For effective treatment, these streams require a reagent which will maintain the excellent selectivity of LIX 64N, and will

Jan 1, 1971

By D. Rahal

All ores have an economic optimum particle size (Wills and Napier-Munn, 2006). This optimum value is often a compromise between the need to achieve adequate liberation for the efficient separation and recovery of valuable minerals and the energy consumed by the crushing and grinding process. It has been recognized for nearly three decades that grinding is the most expensive and least efficient stage in mineral processing (El-shall and Somasundaran, 1984). At that time it was estimated that grinding consumed between 25 and 70% of the total power required in mineral processing. This recognition drove the development of new stirred mill fine grinding technology in the 1990s (Jankovic et.al, 2003; Enderle et. al., 1997; Massey, 2008). These milling technologies have a reduced energy consumption compared to traditional fine grinding using ball mills. In the ?coarser? fine grinding applications this improvement is approximately 30%. The benefits increase to above 50% in ultrafine grinding applications (Lichter and Davey, 2006). Despite these gains, the US Department of Energy reported that an additional energy savings of up to 37% is possible in the minerals industry. They identified continuing research and development and implementing best practices in both grinding and materials handling as the primary avenues for the additional reduction (BCS, 2007).

Jan 1, 2011

By Terry J. Close

Between 1986 and 1989, at the request of the U. S. Bureau of Land Management, personnel from the U. S. Bureau of Mines Western Field Operations Center studied the highly-mineralized, 25,335-acre, Crack Canyon Wilderness Study Area (UT-060-028A), to evaluate its identified mineral resources. The 16-mi-long, 2-mi to 4-mi-wide stud/ area is on the southeast side of the San Rafael Swell, about 40 mi southwest of Green River, Emery County, southeast-central Utah. The study area is underlain by Mesozoic sedimentary beds. Uranium, the principle mineral resource, occurs in two formations. The principle uranium deposits are in mudstone, sandstone, and conglomerate lenses in the 22-mi-long outcrop of the Triassic Chinle Formation which parallels and straddles the northwest boundary of the study area, Some small low-grade uranium occurrences and an extensive gypsum deposit are hosted by the Jurassic-age rocks that underlie the southeast part of the study area.

Jan 1, 1989

By J. B. Zink

The Bureau of Mines developed a spectrochemical method to determine six constituents in coal ash in the following concentration ranges: silica 9 to 63 percent, alumina 7.5 to 35 percent, ferric oxide 2 to 30 percent, calcium oxide 1 to 29 percent, magnesium oxide 0.5 to 6 percent, and titanium oxide 0.5 to 4 percent. Samples of coal ash are fused with a mixture of lithium tetraborate and vanadium pentoxide. The resulting beads are crushed, mixed with powdered graphite, and briquetted. The pellets are analyzed spectrographically, using controlled high-voltage spark excitation. Vanadium serves as the internal standard. Effects due to matrix variations are minimized by fusion with lithium tetraborate. Intensity ratios of selected analytical lines are determined photometrically, Concentrations are read from analytical curves, prepared from synthetic standards, relating log intensity ratios to log concentration. A combustion procedure is used to determine sulfur tri-oxide. The method is most useful when large numbers of coal ashes must be analyzed but a high degree of accuracy is not essential.

Jan 1, 1967

By Kim B. Shedd

The Bureau of Mines measured fiber dimensions on crocidolites (riebeckite-asbestos and magnesioriebeckite-asbestos) from the world's four crocidolite mining regions. The objective of the study was to determine whether there are measurable morphological differences between crocidolite fibers that correlate with the high reported incidence of mesothelioma in miners and mill employees in the Cape Province of South Africa and Western Australia, as compared with little or no reported incidence of this cancer in the Transvaal Province of South Africa or Bolivia. Fiber dimensions measured with the scanning transmission elec-tron microscope showed that crocidolites from Western Australia and the Cape Province have more thin fibers than crocidolites from Bolivia and the Transvaal Province.

Jan 1, 1985

By Yajie Wang

Traditionally, roof falls are usually attributed to bad roof strata and high vertical stress related to the overburden depth. However, roof falls under shallow overburden depth are oflen caused by a high horizontal stress field. Recent studies have proven that the high horizontal stress field, if existing, plays a major role in roof stability. Also the roof conditions are related to the entry diredions under a horizontal stress field. Questions are: How to orient the entry to a favorable direction to prevent the roof falls? If the entry cannot be oriented, how to support it? Through a case study in mine A, this paper analyzes the horizontal stress effect on roof stability. The guideline for the entry orientation is given based on the results of analysis. Additionally, suggestions are made for those entries that cannot be oriented to a favorable direction.

Jan 1, 1998

By Edson Ramos, Rony Choqueneira, Russel Lozada

El artículo refiere un trabajo de investigación que tuvo por objetivo analizar, mediante la electrocoagulación con un diseño de reactor de flujo continuo, la remoción de metales pesados (Pb, Cu y Zn) y turbidez presente en aguas del río Coata (Juliaca), destinadas para consumo y/o recreación. Se detallan las condiciones (2 celdas de flujo continuo conectadas por un canal de tubería), así como los procedimientos efectuados en esta experimentación, que ha obtenido buenos resultados (una eliminación superior al 50% en la primera celda y al 80%, en la segunda).

Oct 30, 2019

By Zhou Lu-Jian

The Port of Shekou is situated at Shenzhen Bay on the east bank of Lingding Ocean. Its coastline is about 6 km long and the water depth near the shore is Favourable. Across the bay is the ' New Territories " of Hong Kong. The port is at a distance of 22-23 seamilesaway from center of Hong Kong and 80 seamiles to Huangpu Harbour of Guangzhou, its highway links with Shen-Guang Highay. Since 19 79 China Merchants Group of the Transportation Department, began to set up Shekou Industrial Zone, the port has been developing and flouri­shing in business. With 15 large or small berths in all, the present portline is 2600 m, and the annual cargo throughout is over 3,000,000 tons and the annual passenger traffic is about 2,000,000 persons. Equalling a medium-scale seaport, it has been officially approved as an oceangoing transit port by the ministry of Transportation. The construction of Shekou port is chara-terized by the self-collected funds and the short construction period. In view of this, the optional plan of the port structure must serve the requirements of simplicity in struture, economy in mate­rial and speed in construction. That accounts for the most application of the sheet piling type to the port in Shekou. Once the project was approved, the cons­truction started. Only within an average period of 7-8 months, a deep water pier was completed and put into operation, which covered series of processes from exploration, designing, tender for con­struction to completion.

Jan 1, 1991

By K Niiranen

Luossavaara-Kiirunavaara AB (LKAB) operates one iron ore mine, three concentration plants and three pelletising plants in Kiruna, Sweden. The current methods of separation at the beneficiation plants are low intensity magnetic separation (LIMS) and reverse apatite flotation, where the wet LIMS stage is regarded as the crucial part of silica separation from the ore. Because future silica levels are expected to increase in the incoming material to the beneficiation plants, geometallurgy has become an important area of development and research.A laboratory-scale methodology was developed for the systematic characterisation of the ore for mineral processing, with the focus on the high silica ore type B2 and newly discovered subtypes. This methodology combines mineralogical, geochemical and process mineralogical characteristics. Automated mineralogy (QEMSCAN®) is used to study the modal mineralogy, the distribution of silicate minerals in different particle size classes after comminution, the deportment of silicon (Si) between various silicates and the degree of liberation and intergrowth of magnetite and silicates. An essential stage in the systematic characterisation of the ore deposit for mineral processing is the estimation and simulation of different parameters from the laboratory scale to the full scale at the concentration plants. This is achieved by using empirical models based on the data collected at the mineral processing plants. As the first step to implement the geometallurgical information, the current geological model is reconstructed with the mineralogy and the two, newly defined subtypes of high silica ore type B2 are separated into different domains.To study the reduction of the SiO2 content in the magnetite concentrate, a large-scale reverse cationic silicate flotation laboratory test program was initiated in early spring 2016. This program investigated potential silicate flotation in the beneficiation plants at the Kiirunavaara site. The second target is to implant mineral processing parameters into the block model based on the new geological model. This information provides a good basis for making a prognosis for mine planning and a quality prognosis regarding the crude ore for mineral processing.CITATION:Niiranen, K, 2017. A geometallurgical perspective on a high-grade iron ore deposit at Kiirunavaara, northern Sweden, in Proceedings Iron Ore 2017, pp 309–318 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Andrzej Walentek

This paper presents the results of numerical modeling of the fractured zone around longwall gateroads. The numerical computations have been based on the results of underground measurements of the fractured zone around longwall gateroads, which were performed for various geological and mining conditions and measured with the use of the endoscopic method with a digital camera. Having results of the underground investigations, trials of duplicating them by the Finite Element Method using software PHASE and the Hoek-Brown failure criterion were performed. In order that the fractured zone predicted by the model-based computations closely simulate that measured underground, some selected parameters in the Hoek-Brown failure criterion were modified based on the earlier determined relations used for prediction of the roof-to-floor convergence in longwall gateroads. As a result, the model-based computations produce results very close to those obtained from the underground measurements. Determination of the fractured-rock zone around the mine roads is of great importance to mining practice, especially in planning and designing supports for longwall gateroads. The influence of the front abutment pressure causes the fractured rock zone around the roads to increase and results in an increase of support load. Moreover, proper determination of the fractured rock zone is one of basic elements in the process of planning roof bolting for mine workings.

Jan 1, 2009

Significant advances have been made in the design of centrifugal slurry pumps that are used for pumping high-density viscous and paste slurries. This paper presents the results of a series of centrifugal pump performance tests that were conducted using an FLSmidth 6 x 4 Krebs millMAX centrifugal pump. The pump was fitted with a dry mechanical seal to prevent dilution of the slurry from gland service water, as the theology of the slurry is sensitive to small changes in slurry density. Tests were done using paste kaolin slurry with Bingham yield stress values between 578-1 120 Pa and plastic viscosities between 728 and 1491 mPa.s. The viscous properties of the paste during each pump test were measured using a rotational viscometer. Pump head and efficiency de-rating were measured and compared to the correlations of Walker and Goulas (1984). The test data shows the pump's best-efficiency point (BEP) changes and shifts to the left of the performance curve. The pump efficiency decreases as the slurry yield stress increases. The head de-rating data shows more head de-rating at the low flow rates compared to the high flow rates for the high viscosity slurry, which is in line with the findings of Walker and Goulas (1984). This paper demonstrates that it is possible to pump very viscous, high yield stress slurries with limited head and efficiency de-rating using centrifugal pumps, provided that positive suction conditions are maintained at all times.

Jan 1, 2012

By C. Thiart

Kriging is an interpolation technique for predicting unobserved responses at target locations from observed responses at specified locations. Kriging predictors are best linear unbiased predictors (BLUPs) and the precision of the BLUP is assessed by the mean square prediction error (MSPE), commonly known as the kriging variance. Both the BLUP and the MSPE depend on the covariance function describing the spatial correlation between locations and on specific parameters. The parameters are usually treated as known, whereas in practice they invariably have to be estimated and the empirical BLUP (that is, the EBLUP) so obtained. The empirical or estimated mean square prediction error (EMSPE), or the so called ?plug-in? kriging variance estimator, underestimates the true kriging variance of the EBLUP, at least in general. In this paper five estimators for the kriging variance of the EBLUP are considered and compared by means of a simulation study in which a Gaussian distribution for the responses, an exponential structure for the covariance function, and three levels of spatial correlation ? weak, moderate, and strong ? are adopted. The Prasad-Rao estimator obtained using restricted or residual maximum likelihood (REML) is recommended for moderate and strong spatial correlation and the Kacker-Harville estimator for weak correlation in the random fields.

Jan 1, 2014

By P. V. Fillo

This paper describes Mohave Mining and Milling Co. methods of mining and milling manganese ore in Arizona. It is one of a series of publications prepared by the Bureau of Mines on methods and costs in various mining districts in the United States. Production of manganese ore, as such, in Arizona began in 1915. Before this time manganiferous ores had been mined primarily for silver content and used as a smelter flux. From 1916 to 1918 approximately 69,000 long tons of manganese and mangsniferous ores were mined. After World War I production dropped to almost nothing until World War II, during which period more than 24,000 long tons were produced. A lull in mangonese mining occurred after World War II, having production rates of only a few hundred tons annually through 1952.

Jan 1, 1963

By W. D. Hausel

The Wyoming craton in the western United States is a favorable terrane for diamond deposits. The craton hosts a variety of ultramafic, ultrabasic, and ultrapotassic rocks. Additionally, a few hundred 'kimberlitic' heavy mineral anomalies and some geophysical and remote sensing anomalies indicate the presence of undiscovered, mantle-derived, pipes in the craton. The Wyoming craton is separated into a Wyoming 'archon' known as the Wyoming Province, and the Colorado 'proton' known as the Colorado Province. The 'archon' underlies much of Montana and Wyoming and continues north into Alberta and Saskatchewan; the Colorado 'proton' underlies much of Colorado and a small portion of Wyoming. Although most exploration geologists would consider the 'archon' the most favorable terrane for commercial diamond deposits, the 'proton' has produced more than 120,000 diamonds, while the 'archon' has not been very productive.

Jan 1, 1996