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By J. Gholamnejad

In open pit mine planning and design, push back mine sequencing is widely used for long-term production planning. In push back design, a series of nested pits is generated and then considered as possible push backs with regard to the minimum push back width requirements. These nested pits are produced by parameterizing on one economic parameter like commodity price, mining or processing cost, stripping ratio, etc. The most important characterization of these push backs is that the innermost push back has the highest value per ton, the second innermost push back has the second highest value per ton, and so on. These nested pits are generated based on the best estimates of grade within a representation of the orebody in a three-dimensional matrix form. Therefore, the inherent uncertainty associated with reserve estimation (for our discussion, grade uncertainty) is not taken into account when push backs are designed. These methods do not attempt to establish which part of the deposit is likely to be worth most. This paper introduces a new algorithm that incorporates ore grade uncertainty during the pushback design process. The suggested strategy tries to seek to schedule risky blocks later in the extraction sequence. Keywords: open pit mine, push back, ore grade uncertainty.

Jan 1, 2007

By A N. Parry

In May 2018 Kasbah Resources Limited (“Kasbah”) completed an ore sorting test work program which was a precursor to releasing in July 2018 an updated Definitive Feasibility Study (“DFS”) for the Achmmach Tin Project in Morocco, which it is proposing to develop along with its joint venture partners. The testwork program evaluated ore sorting as a pre-concentration option to achieve early elimination of gangue and the low-grade component of ROM feed, thereby potentially:  Significantly upgrading the head grade of tin to the downstream processing plant.  Significantly reducing the required throughput capacity (and projected capital expenditure) of the downstream processing plant.  Reducing total consumables, power and water requirements in downstream processing.  Increasing the recovery of tin in the gravity and flotation circuit due to the higher feed grade achievable with ore sorting.  Reducing tailings tonnage, tailings cost and environmental footprint.  Using sorter rejects for mine backfill or road base applications. Key aspects of the design of the metallurgical testwork program centred around the need to ensure that samples representative of ROM ore feed (including projected mining dilution) were selected for the ore sorting testwork. The design and implementation of the ore sorting bulk testwork program is described, as well as a summary of the test work results and a discussion of the enhancement of the project economics reported by Kasbah, which led the company to adopt ore sorting as part of the proposed processing circuit in the updated 2018 DFS.

Nov 10, 2020

By X Zheng, P Manton

Pebble recycle crushing circuit performance at Telfer has historically fallen significantly short of the design product P80 of 12 mm. An investigation was undertaken to evaluate the current pebble crusher circuit performance, quantify the optimum performance achievable with the existing circuit and examine the impact of pebble crusher performance on the overall grinding circuit throughput. The primary objective of this investigation was to develop an operating strategy that could consistently deliver the finest possible pebble crusher product to maximise the overall plant throughput.The pebble crusher specific energy (Wc) was proposed as a key control variable for pebble crusher operation based on the results of plant survey work. Over the range of pebble crusher specific energies encountered at Telfer, a strong linear relationship was found to exist between Wc and the crusher product size. This direct linear relationship between specific energy and crusher product size remained constant regardless of how the change in specific energy was generated, ie through changes to the crusher closed side setting (CSS), feed rate, liner profile or moisture content. Key findings for the Telfer pebble crushing circuit were: each 0.1 kWh/t change in Wc resulted in a 4.9 per cent to 6.0 per cent change in plant throughput, each 1 mm change in pebble crusher CSS resulted in a 2.2 per cent to 2.6 per cent change in plant throughput, and 0.57 tonne of new feed was displaced for each tonne of crushed pebbles recycled to the semi-autogenous grinding (SAG) mill. The presence of an existing 3000 tonne pebble stockpile between the SAG mill and pebble crushers provides an opportunity to manipulate the feed rate to the pebble crushers independently of the SAG mill pebble production rate. This flexibility, along with excess pebble crushing capacity, enables the pebble crusher specific energy to be maximised the majority of the time. Pebble crusher specific energy has subsequently been incorporated as an online crusher control measure to assist in maximising plant throughput.

Jan 1, 2009

By A. D. Nicholson

This paper presents an approach to quantitatively calculate the neutralization of acid by silicate minerals, based on the chemical kinetics of acid reacting with silicates. This approach incorporates incongruent dissolution mechanisms and the effects of silicate iron content on net acid consumption, and offers guidelines for considering the extent to which specific silicate minerals will react. This approach differs from previous methods of estimating silicate buffering: it is based more on the fundamental chemistry of acid generation, and less on potentially misleading empirical measurements of acid neutralization.

Jan 1, 2002

By Alessandra Savazzini dos Reis

A crescente preocupação em relação às áreas de proteção ambiental e ao alto consumo de argila, matéria-prima da cerâmica vermelha, ocasiona a indisponibilização progressiva de reservas de argilas no Brasil. Com isso, vê-se a necessidade de incorporar resíduos na massa argilosa para confecção de produtos de cerâmica vermelha. A indústria de cerâmica vermelha brasileira consome cerca de 10 milhões de toneladas de argila ao mês para produção de telhas e blocos. Na própria olaria são gerados resíduos, tal como, o resíduo de massa cerâmica crua originado na etapa de conformação das peças. Este trabalho visa incorporar o resíduo de massa cerâmica crua na massa argilosa usada em cerâmica vermelha. O resíduo foi caracterizado por meio de ensaios de FRX, DRX, limites de Atterberg e distribuição de tamanho de partículas. Corpos de prova feitos com massa argilosa e resíduo em teores variando de 10% a 90% (massa) foram conformados, secos à 110ºC, queimados à 900ºC em forno industrial e submetidos a ensaios de absorção de água, porosidade aparente, massa específica aparente e resistência à compressão. Os resultados evidenciaram que as propriedades cerâmicas avaliadas nos corpos de prova da massa argilosa incorporada com o resíduo atendem aos valores das argilas-padrão brasileiras para cerâmica vermelha.

Aug 17, 2017

By Artur Camposo Pereira

Cerâmicas argilosas foram processadas com adição de até 30% em peso de resíduos de pedra ornamental e queimadas a 900, 950, 1000 e 1050°C. Esta adição contribuiu para ajustar a plasticidade do corpo da argila e aumentar a densidade seca aparente, que ocasiona um empacotamento mais elevado das partículas. A cerâmica adicionada diminuiu sua retração linear com a quantidade de resíduos e evita assim alterações dimensionais excessivas nos produtos finais. Outra vantagem foi a diminuição na absorção de água com resíduos adicionados. As resistências à flexão e à compressão sofreram uma diminuição associada à adição de resíduos. Isto foi atribuído à grande quantidade de quartzo nos resíduos, que gera rachaduras e enfraquece o produto final. No entanto, até 30% em peso de adição a resistência mecânica, de acordo com a norma ASTM, é ainda satisfatória para utilização como cerâmica de pavimentação.

Oct 30, 2017

By E. A. Devuyst

A unique process for removing cyanide and base metal complexes from industrial waste streams was patented by Borberly et al. (1984). The process uses S0, (liquid or gas, or solutions of sulfite salts, or from burning elemental sulfur), plus air that is dispersed in the effluent using a well agitated vessel. Acid produced in the oxidation reactions is neutralized with lime at a controlled pH generally in the range 7 to 10. The reaction requires the presence of soluble copper as a catalyst that can be supplemented by copper sulfate if necessary. The process can be applied to the detoxification of gold and silver mining waste streams, such as carbon-in-pulp (CIP) tailing pulps, barren solution bleeds, pond waters and heap leach rinse solutions and also to plating shops waste waters. The S02/Air process has substantial advantages over two of the main alternative methods of cyanide destruction, namely alkaline chlorination and hydrogen peroxide. Alkaline chlorination is highly penalized in terms of reagent consumption. Chlorine is a strong oxidant reacting with species other than cyanide present in the effluent such as thiocyanate and sulfides. Furthermore, alkaline chlorination is an incomplete detoxification process. Iron cyanide is not removed and the potential for harmful byproducts species exist. Consequently, final effluents may be subject to additional treatment in order to comply with regulatory demands.

Jan 1, 1991

By Leonardo Araújo Peruch, José Fagundes, Henrique Carneiro Pinto, Marco Túlio Costa, Nayara Coutinho, José Fabiano Martins Assunção

The objective of this project was to increase the hot charge by reducing reheating energy consumption and raising the productivity of ArceloMittal Tubarão's hot strip mill by changing the HSM’s schedule process with optimization of the relocation process of slabs after HSM’s chance with focus on slab temperature in reheating time. The project began with the revision of metallurgical rules for the relocation of materials, definition of criteria temperature setting (hot / cold), definition of restrictions of the process and review of modus operandi scheduling process. With the implementation of the process / system it is expected to achieve a 10% increase in the hot charge index in slabs reheating furnaces and increase productivity of the ArcelorMittal Tubarão hot strip mill

Oct 3, 2019

By Emma Arakelova

An increase in concentration of a Zn-containing volatile complex for synthesis of ZnO films was investigated when processing their target by ultraviolet radiation emitted by mercury lamp. The experiments were carried out using a flow-type quartz reactor. ZnO tableted target was preliminarily irradiated during 2 to 7 hours. H2O2 (98%) vapor at 25Pa passed through the reactor with ZnO target at 373K. As substrate material, five subsequent quartz cylinders were used at 423K. The experiment lasts 4 hours. H2O2 decomposition on ZnO surface was accompanied by formation of a Zn-containing volatile complex which passed in gas phase and decomposed on the substrates with isolation of final ZnO. The concentration of the Zn-containing volatile complex (N) in gas phase increases with UV pre-irradiation time (t) (without irradiation N = 1.05 1011 particles/cm3; after t=2 hours, N = 5.19 1011 particles/cm3, after t=4 hours, N = 9.95 1011 particles/cm3; after t=7 hours, N = 1.86 1012 particles/cm3.

Jan 1, 2006

By L. Szecowka, M. Poskart, Siwka M. . J.

Oxides of nitrogen, created during combustion, are the most hazardous components of atmospheric pollution. However, it is possible to limit the negative influence of hazardous components on the natural environment. An experimental appartatus was built to determine the influence of the following "primary methods" on the reduction in concentration of NOx: air staging, reburning and flue gas recirculation. The influence of the simultaneous usage of the primary methods on reduction in NOx emissions was also examined. A significant increase in the efficiency of NOx reduction was achieved in two cases.

Jan 1, 2004

By Paul J. Axtell

The results of in-situ geophysical cross-hole tests on improved soil by soil mixing (SM) and jet grouting (JG) are described. This testing was conducted on soil improved by SM and JG columns constructed in the downstream free-field of Tuttle Creek Dam near Manhattan, Kansas as part of the seismic retrofit. Results of similar geophysical testing performed on untreated soil in the vicinity of the Downstream Test Program (DTP) area, as well as beneath the embankment at several locations, are also described and used for comparison purposes. In-situ shear moduli are also compared with those determined in laboratory resonant column tests. The increase in stress wave velocities and associated shear moduli by SM and JG treatment are presented for use in liquefaction potential and seismic deformation analyses of SM or JG treated soil. This data is required to determine the decrease in liquefaction potential and earthquake-induced permanent deformations due to SM or JG with respect to that of untreated soil.

Jan 1, 2008

By Fumio Hashiuchi, Yushiro Hirai, Masatoshi Maeda, Toshihiro Nagata

"Increase in the copper smelting capacity at Saganoseki Smelter & Refinery was attained through various improvements in the PSconverters and the flash furnace. Two of the major innovations in the converting process were: a new operational technology which avoids increase in the copper content in the converter slag even when higher copper grade matte (65%) are treated in the slag making stage and a technology which shortens the operational interruption time which is caused by coolant charging. The latter was realized by introducing a new automated coolant charging system with which it was made possible to charge the coolant without stopping the blowing into the converter. These improvements brought about a remarkable increase in · the production capacity per converter and an annual production of 450,000 tons of copper without adding new furnaces was made possible. In addition, good results have been obtained of the tests with modified tuyeres to further increase the production.IntroductionIn a bid to renovate its Saganoseki Smelter & Refinery and to establish a leading production unit in terms of global competitiveness, Nippon Mining & Metals undertook major restructuring efforts since 1994. One of its themes was the shift from· a two-flash furnaces operation to a single-flash furnace operation. The shift was successfully completed in 1996 while maintaining the production at the same level (330,000 tons per annum of copper). Then, the productivity was enhanced to 450,000 mtpy without adding new furnaces through technological and operational improvements. It is now planned to increase the smelting capacity further to 470,000 mtpy this year.Some technological and operational improvements in the matte converting process and the new plan resulted from the tests with modified tuyeres are presented in this paper."

Jan 1, 2000

By Y. G. Yaroshenko, V. Y. Baldin, Y. M. Gordon

The manufacture of sulphuric acid from the off-gas of pyrometallurgical processes in the production of heavy metals is one of the common methods of effective recycling of sulfuric anhydrite. The new Impact-Inertial Devices with the rectangular contact channels (IIRCh) and the internal circulation of liquid allow the injection of an absorber into the phase's interactive cell by utilizing the gas stream energy and by this way increasing the sulphuric acid yield and reducing the power consumption. These devices have the following advantages: simplicity of design, smaller size, low capital expenses, absence of irrigating system, high operational reliability, simultaneous cleaning of solid, gaseous and liquid impurities and also cooling of gases etc. The IIRCh efficiency is almost 18 % higher and they require 1.3-2 times lower energy when compared with Venturi Absorbers. Also the elevation of spraying nozzles or injectors is 1.5 times lower in the IIRCh case.

Jan 1, 2004

By C. B. Piazzarollo

Ceramic materials exhibit dispersion results after being subjected to various levels of stress, from the point of view of mechanical strength. With the focus on sustainable development and to improve the strength of these material, was incorporated ornamental rock waste into clay in up to 10% in mass to conform some samples, that was fired to 750ºC, 850ºC and 950ºC and submitted to technological tests. This paper presents an analysis of the technological properties of the samples through the use of Weibull statistic to determine which the best firing temperature for these red ceramic materials. The Weibull Modulus indicates a greater homogeneity for samples with 10R at 950ºC.

Jan 1, 2015

By T. A. Toney, L. R. Fish, P. J. Bethell

With new lightweight designs, spirals have become standard equipment in coal preparation plants worldwide. To their credit, spirals typically show very low coal losses to the refuse stream under most operating conditions. However, spirals do tend to separate at cut points in excess of 1.80 S.G. Attempts to obtain lower cut points have typically resulted in coal losses to middlings. Middlings retreatment with secondary spirals is therefore becoming common place. Other forms of retreatment with water-only cyclones, hydrosizers and recirculation have been attempted with some success. This paper reports on a novel (patent applied for) approach to retreating spiral middlings in a heavymedia cyclone circuit.

Jan 1, 2000

By T. A. Toney

With new lightweight designs, spirals have become standard equipment in coal preparation plants worldwide. To their credit, spirals typically show very low coal losses to the refuse stream under most operating conditions. However, spirals do tend to separate at cut points in excess of 1.80 S.G. Attempts to obtain lower cut points have typically resulted in coal losses to middlings. Middlings retreatment with secondary spirals is therefore becoming common place. Other forms of retreatment with water-only cyclones, hydrosizers, and recirculation have been attempted with some success. This paper reports on a novel (Patent Applied For) approach to retreating spiral middlings m a heavy-media-cyclone circuit.

Jan 1, 1998

By M. Townsend, E. L. Petsonk, H. Abrons, E. Daniloff, K. Kinsley

Workers exposed to certain inhaled dusts may show increased levels of nonspecific airways responsiveness (AR). In some studies, cigarette smokers have also been reported to have increased levels of AR. As part of an ongoing study, we compared the results of preshift methacholine inhalation challenge, spirometry, and smoking and occupational histories, in 191 under-ground bituminous coal miners (M) and 215 non-mining control workers· (C) . All M and c were selected to have normal baseline% predicted FEVI (PPFEV). Mining tenure was recorded as years worked underground (YRUG) and at the coal face (YRFC). AR was assessed as the% decrease in FEVI from baseline divided by the dose of methacholine delivered. M reported similar years smoked (YRSM) but fewer pack-years* (PY) than c~ Overall, both increasing YRSM and PY were associated with more AR*. Smoking C* but not M showed increased AR with increasing PY. In smoking and nonsmoking M, baseline AR and PPFEV showed no association with YRUG. The level of AR was inversely related to YRFC*, possibly representing selection away from dustier jobs. AR was inversely correlated with PPFEV*. In this study, AR and baseline PPFEV were not significantly associated with mining tenure, but cigarette smoking was related to both baseline lung function and level of AR. * p < 0.05 (Supported in part by Grant Gll35142, us Bureau of Mines, Generic Mineral Technology Center for Respirable Dust.)

Jan 1, 1989

By W. Boas, R. Silva, D. Yumi, L. Steffen

The continuity of the flow and stages within the mining process is essential to achieve success in its operation and results, especially when it comes to a gold mine. During the first seven months of 2022, crushing at the Morro do Ouro Mine had 19 stops in the primary crusher due to equipment blockage/obstruction, this could be due to the size of the material that was blasted with explosives and fed. The feeding of coarse material to the crushing plant impacts the operation in several ways, for example, premature wear of the equipment, reduction in the supply of the remainder of the beneficiation, reduction of the buffer pile and damage to the conveyed belt. In a mine located far from the community, the fragmentation improvement is mainly related to load increments or some other relatively simple change. However, when it comes to a mine located close to communities, alterations of this type must be analyzed in detail, as it can have an impact mainly in relation to vibration and flyrock. Aiming to improve the efficiency of the blasting, mainly in relation to the result of fragmentation, a project was created to improve the efficiency of the blasting with a focus on reducing the crushing stoppage and reducing the amount of material discarded due to inadequate granulometry. During the evolution of the project, several improvement solutions were proposed, for example adjustment of the power factor in relation to the geological characteristics of the rock mass, drainage, blasting geometry, vibration reduction techniques and several operational improvements. By using the techniques and methods identified as improvements during the project, it was possible to observe and quantify improvements in relation to the fragmentation of the blast. During the months of January to July 2022 there were 19 events. It was estimated that at this rate there would be 14 more blockage events, but there were only 3 events and that meant a 79% reduction in blockage. In addition to the reduction in crushing shutdown events, there was also a 53% reduction in the amount of ore that is discarded due to inadequate granulometry and, with that, the feed rate of the grinding system was able to reach the maximum feed limit due to the material being fed to the mill well fragmented, contributing to increase the production and productivity of the beneficiation process at the Morro do Ouro Mine in Paracatu-Minas Gerais-Brazil.

Jan 1, 2024

By B. P. Spigarelli

To meet the growing need for CO2 capture and storage technology, Michigan Technological University is researching CO2 capture and storage using carbonate solutions. The objective of the present study was to increase the absorption rate of CO2 into the carbonate solution without reducing the absorption capacity of the solution. This approach used a polypropylene glycol methyl ether (PPGME) as a surfactant to chemically alter the gas bubble size. Experiments were conducted to study the absorption rate of CO2 at varying surfactant concentrations of 0, 0.12, 0.24, 0.36, and 0.48 g/L. Results showed that as the concentration of surfactant increased in solution, the absorption rate also increased. The CO2 absorption rate increased from 3.45 mmol/min CO2 at 0g/L PPGME to 3.92 mmol/min CO2 at 0.48 g/L PPGME. This amounted to a 14% increase in the CO2 absorption rate with no decrease in absorption capacity of the solution.

Feb 27, 2013

By B. P. Spigarelli

To meet the growing need for CO2 capture and storage technology, Michigan Technological University is researching CO2 capture and storage using carbonate solutions. The objective of the present study was to increase the absorption rate of CO2 into the carbonate solution without reducing the absorption capacity of the solution. This approach used a polypropylene glycol methyl ether (PPGME) as a surfactant to chemically alter the gas bubble size. Experiments were conducted to study the absorption rate of CO2 at varying surfactant concentrations of 0, 0.12, 0.24, 0.36 and 0.48 g/L. Results showed that as the concentration of surfactant increased in solution, the absorption rate also increased. The CO2 absorption rate increased from 3.45 mmol/min CO2 at 0 g/L PPGME to 3.92 mmol/min CO2 at 0.48 g/L PPGME. This amounted to a 14% increase in the CO2 absorption rate with no decrease in absorption capacity of the solution.