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By Jerry E. Olson

In 1984, the U.S. Bureau of Mines conducted a mineral survey of the Black Rock Desert Wilderness Study Area (WSA) (NV-020-620), which covers approximately 319,000 acres in Humboldt County, Nevada. About 90% of the WSA is underlain by Pleistocene desert playa sediments; the remainder is comprised of Jurassic-Triassic metamorphic rocks, a Cretaceous intrusive and Tertiary volcanic rocks. Most of the WSA is within a down-dropped fault block of the Basin and Range physiographic province. No mines or evidence of major exploration were identified within the WSA; but five claim blocks within or adjacent to the WSA and zones of anomalous character as defined by the Bureau of Land Management were examined. No mineral resources were identified, but anomalous gold, silver, and indicator element content of samples taken near Pinto Hot Springs indicate resources may exist. Lithium content of samples from near-surface sediments on the desert playa is too low for resources, out geologic conditions are favorable for higher concentrations at depth. Occurrences of zeolites are not considered to be of commercial interest. Approximately 27,000 acres are held under geothermal lease, and most of the WSA is of interest for oil and gas. No evaluation of these commodities was made by the Bureau of Mines

Jan 1, 1985

By Len Blackman

The Absaroka-Beartooth Study Area is a tract of approximately 1.4 million acres of National forest land in southern Montana, part of the Greater Yellowstone Area. This study evaluated the mineral potential of four mineral terranes containing undiscovered resources in the area. The geological data is probabilistic, with estimates of the possible number: of deposits and their grades and tonnages. Possible future development scenarios range from no development to many mines, including some very large. As two thirds of the study area is within the Absaroka-Beartooth Wilderness, the future development scenarios reflect the area's mineral potential, not what we expect to see in the foreseeable future. Based on the analysis performed on these four terranes, the most likely future scenario for the study area would include the potential for two medium sized, (predominately) gold, mines, each employing a few hundred workers. There is a small chance, less than 5%, that a large Porphyry Copper or Superior Iron deposit would be discovered and be economically feasible to develop.

Jan 1, 1994

By Thomas J. Peters

During the 1982 Bureau of Mines study, 55 lode and 17 placer claims were held in the RARE II area. An estimated 150 lode claims and 50 placer claim, have been located in the study area; five were patented. There are no mineral leases. Gold has been produced from 8 lode mines and stream gravels have been worked for placer gold at 4 sites. Two suction dredges were active in stream gravels, but no significant gravel bars are identified. Identified mineral resources in the Weaver Bally area are gold and byproduct silver. The identified resources are at the Globe Mine, where approximately 33,000 tons of indicated marginal reserves (2,000 tons in the RARE II area, and 31,000 tons in the adjacent proposed Trinity Alps Wilderness) contain 0.45 oz gold per ton and probably 0.1 oz silver per ton. There are an additional 150,000 tons of inferred marginal reserves (35,000 tons in the RARE II area, and 115,000 tons in the adjacent proposed wilderness) averaging 0.38 oz gold per ton and probably 0.1 oz silver per ton. There is high potential for additional resources at the Globe Mine.

Jan 1, 1983

By R M. S Watsford, M Davis

In 2015, MMG Limited commenced further action to improve operating margins and establish a blueprint for future growth in the Australian environment. This action was taken in the context of weakening metal prices and high input costs that arose during the Australian minerals boom.MMG was formed in June 2009 following the purchase of the majority of assets of OZ Minerals Limited by China Minmetals Corporation (CMC) through its subsidiary China Minmetals Non-ferrous Metals Co Ltd (CMN).Since formation MMG has been implementing a business model to deliver a standard way of operating. The overarching purpose of the business model is to enable fast integration of acquired assets to realise improved productivity and performance. CMN established MMG as a vehicle to reach their growth targets through further development or acquisition of mineral assets in jurisdictions external to mainland China.The business model is underpinned by the MMG operating model. The operating model defines how MMG is arranged to deliver the company strategy.This paper describes the application of the operating model to the formation of the Australian operations into a single business unit from multiple stand-alone operating sites. The development and impact of the business model on MMG’s performance is also presented.The extension of the operating model to the Australian operations has led to improvement in safety performance, direct costs and productivity. These improvements have been achieved through reducing duplication, simplification of systems and rapid deployment of improvement initiatives.The successful implementation of the operating model to Australian operations strengthens the platform for further growth. Hence, delivering on the aim of the business model.CITATION:Watsford, R M S and Davis, M, 2016. MMG’s Australian operating model – the implementation, successes and learning, in Proceedings International Mine Management Conference, pp 291-302 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

By D Connelly

There is now a new generation of mobile crushing and screening plant systems available which have been developed based on the motivation of reducing truck haulage. Newly designed mobile crushing and screening plant systems have the advantages of mobility, flexibility, economy and reliable performance, making this system very appealing for small- to medium-sized projects or projects where a number of resources are separated by distance.A brief review of the past history and experience with transportable crushing plants provides an insight into some of the issues with transportable plants in mineral processing. A closer look at a simple model based on exploiting small but high-grade orebodies suggests the concept has merit, however there are many more engineering, logistics, legal, technical and management aspects which have limited the application of such a concept in the resource sector. This paper explores the concept in detail and endeavours to analyse the preferred commodities and scenarios under which the concept could be used and the economic and logistical limitations for iron ore. The paper also looks at the risk assessment criteria to be applied in selecting the type of resource projects where the model could be applied successfully. Other aspects considered in this paper are the project planning requirements, technical and economic feasibility, bankability and operability. Reference is made to the operating experience of contractors at a number of sites and feedback from the resource companies as managers of the projects.CITATION:Connelly, D, 2013. Mobile crushing and screening plant applications for small- to medium-sized iron ore projects, in Proceedings Iron Ore 20 13, pp 349-354 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

To develop a reliable, remotely-controlled, mobile roof support to eliminate the need to set posts, cribs, or props while extracting coal pillars. Approach The primary danger during pillar extraction is premature caving of the mine roof. The roof must cave predictably and dependably to ensure the safety of miners. Support during retreat mining is usually obtained by setting posts, cribs, props, roof bolts, or a combination of these devices. These are set manually by miners in the working area. To help minimize the danger to mine workers and to equipment posed by premature falls, the Bureau of Mines developed the mobile roof support (MRS) system to secure the roof during pillar extraction. How It Works The Mobile Roof Support (MRS) is eight-feet-wide, ten-feet-long and five-feet-high, with twelve inches of ground clearance. It is ruggedly built and exerts less than 20 psi ground pressure. The MRS is powered by a 40-hp, 460-v AC permissible motor. The reversible, variable tram speed is 80 ft/min on a 20-percent grade. It is tire-mounted, has a trailing cable, and is remotely controlled either by a radio or a tether communication cable. The machine carries four 50-ton jacks which serve as props for working heights from seven to fifteen feet. Two jacks are chassis-mounted and two are on swing arms. Each jack has a cap which distributes the roof load to three paints. The swing jacks form a breaker row to stop falling roof and prevent caving Into the work area. One jack has a visual load indicator and a second is wired to the machine lighting system. Blinking lights indicate when the preset loading is being exceeded. In the case of excessive loads, an ability to remotely jettison either or both swing jacks has been incorporated into the system to permit removal of the MRS while the roof is still supported.

Jan 1, 1985

By Adam Zagorski, Rusty Lucido, Curt Scheyhing

"The current California Department of Transportation (Caltrans) practice based on AASHTO LRFD Bridge Design Specifications is to use the O’Neill and Reese method (FHWA, 1999) for calculating the side resistance and base resistance of Cast-in-Drilled-Hole (CIDH) piles / drilled shafts. In this calculation, end bearing is typically neglected for piles constructed using a wet method due to questionable reliability of end bearing resulting from soil disturbance and inadequate cleaning of the base. Pressure grouting below the tips of drilled shafts in cohesionless soils has long been used worldwide to provide reliable end bearing capacity, but for decades it was relatively unused in this country. It has been used increasingly in the United States over the last decade. Before this project tip grouting has not been utilized on or accepted by Caltrans to maximize piles end bearing capacity. This project proved that tip grouting to mobilize reliable base resistance can be successfully implemented on a full-scale bridge project requiring over 350 large diameter shafts.For the Gerald Desmond Bridge Replacement Project, Shimmick/FCC/Impregilo, JV utilized a temporary Oscillator casing to the full depth to install CIDH piles. Piles were constructed by the wet method and then pressure grouted below the pile tip. A tip grouting procedure for these large diameter shafts was developed and tested to specifically address the geology and constraints of the project. This procedure was then proven during the Load Testing of test piles during the Test Shaft construction phase of the project. Tests showed a minimum reliable base resistance of 150 ksf could be mobilized in very dense sand at a downward movement of 5% of the pile diameter for piles ranging from 4.9 to 8.2 feet in diameter. By tip grouting, the length and diameter of the piles were significantly reduced."

Jan 1, 2017

By A. Vien

MOCCA is a Multivariable Optimal Constrained Control Algorithm developed specifically for non-square industrial control applications with practical difficulties such as interactions, time delays, constraints, modelling development, etc. MOCCA consists of an off-line simulation/translation module, for tuning the control parameters, and an on-line module that implements the designed control law. This paper describes an evaluation of MOCCA on the Hemlo grinding circuit which comprises one open circuit ball mill and two closed circuit ball mills in series. In this case a 4x4 unconstrained control problem was considered. The manipulated variables included the fresh ore feed rate and three pump box water additions. The controlled variables were the grinding circuit product particle size and three pump box levels. In this application soft constraints were implemented through control action and control error weighting. The feedforward capability of MOCCA was used to compensate for a measured water flow disturbance to one of the pump boxes. MOCCA performed very well during plant evaluations when compared to the original classical multi-loop control strategy and proved to be quite robust. Perhaps most importantly, the process engineers and plant operators have a high level of comfort both in understanding MOCCA's general operating principles, and with its demonstrated performance.

Jan 1, 1991

By A Califice, E Pirard, M Benzaazoua, R Mermillod-Blondin

Image analysis is more and more considered as a powerful tool for quantitative analysis of ores and concentrates. Apart from being very much dependent upon the quality of the imaging principle and the adequacy of the imaging sensor, quantitative image analysis is also the result of a long chain of material, image and pixel sampling strategies. The most reliable way to demonstrate the accuracy and the precision of modal analysis obtained from images is probably to use a blended material with known proportions of pure minerals and confront the results obtained from different analytical tools. This operation has been performed on a series of mineral blends mimicking the tailings of a flotation operation in a plant operating on massive sulfide mineralisation. The intention was to be able to better predict acid mine drainage potential from direct mineralogical observations. Selected sulfide minerals: pyrite (Py), pyrrhotite (Po), chalcopyrite (Cp) and sphalerite (Sp) were mixed as variable amounts within gangue minerals (quartz, calcite, dolomite and siderite). Typical blends contained six to ten per cent (Py); one to three per cent (Po); 0.5 to one per cent (Cp, Sp); 15 to 40 per cent carbonates and 40 to 75 per cent quartz by mass. The 1000 gram blends were carefully sampled and prepared for X-ray diffraction, chemical analysis by ICP-AES and optical microscopy image analysis (OMIA). Results obtained for the different analytical techniques are compared and discussed revealing the limits and strength of each method in the accurate quantification of sulfide and gangue minerals.

Jan 1, 2008

By Youzhen Zhang

The drilling boom is the key component of a roof bolter, and it has significant impact on the performance, safety, and reliability of the overall working device. In this paper, the experimental modal parameters of a drilling boom at low frequencies are identified with the Laplace wavelet correlation filtering method. Based on the obtained experimental parameters, a finite element model of the drilling boom is revised using an optimization algorithm to improve its accuracy. The dynamics of the drilling boom are analyzed through its modal and harmonic response. As a result, an improvement for the drilling boom is proposed to fix the weak links and enhance the dynamic performance.

Jan 1, 2012

By Wenxuan Xu, Shusen Cheng, Tian Chen

Pulverized coal injection (PCI) can generate heat and reducing gas in the raceway and replace some expensive metallurgical coke in the blast furnace ironmaking process. In this paper, a three dimensional mathematical model of the raceway including the coke bed has been developed to simulate the complicated phenomena of pulverized coal injection. The effects of oxygen enrichment, particle diameter in the raceway are investigated in this study. The establishment of the 3D model is expected to analyze the raceway working state accurately and optimising the PCI operation of blast furnaces.

Mar 1, 2017

By Frank F. Aplan, Edward C. Jr. Dowling, Richard R. Klimpel

Thirteen kinetic models that mathematically describe the flotation process have been statistically evaluated for the flotation of copper, lead and zinc ores. Comparisons have been made for a variety of circuits involving roughing, cleaning, scavenging and regrind followed by cleaning. Variations in collectors, frothers, depressants and activators have been considered. Based on the statistical criteria used for the evaluation, and the reagent, circuit and ore variations studied, the most reliable flotation models have been identified and subsequently used to characterize the metallurgical results.

Jan 1, 1986

By R. P. King

"A model of the flotation process can be used effectively for design and control. For design purposes it can be used to predict the performance of a large plant from laboratory and pilot plant data. It can be used for control purposes to assess the utility of any proposed operating modification to an existing plant, and it can also be used to determine optimal control settings for best operating performance.A model has been developed that will allow for variations in feed properties and for variations in fineness of grind. The model can be used to assess the effects of reagent addition rate, aeration rate and pulp level on plant performance and these are the control variables that are used individually or together in all operating flotation plants. The model provides for a distribution in the values for flotation rate constants, particle size and mineral fraction, and, because of its complexity, requires a large computer when it is to be applied to a typical plant configuration. The computational method that is used to apply this model to such configurations is described in this paper, and particular attention is paid to the problem of allowing for feedback of tailings from cleaners and recleaners."

Jan 1, 2014

By D. G. Almond

Nkomati Nickel Mine in South Africa processes one of the world?s hardest ores in a 375k TPM autogenous grinding circuit. The plant employs an unconventional processing circuit, comprising a primary autogenous mill (AG or FAG) and pebble crushing circuit followed by a secondary hybrid pebble/ball mill and classification cyclone cluster. Advanced Process Control (APC) or Expert Control is now generally accepted as an advantage in most modern high capacity concentrator grinding circuits. This paper reviews the installation of model predictive control at Nkomati and examines the results and benefits of installation in an autogenous mill during plant ramp-up. The paper also demonstrates how predefining process control objectives together with good plant and supplier cooperation can achieve a robust and reliable APC implementation on a very short site program. The results conclusively demonstrate operational and economic benefits during circuit operation with the advanced process control system ON. Production performance and circuit stability were significantly better than during manual control.

Jan 1, 2012

By K. Becerra, D. G. Almond, T. D. Maru

"Nkomati Nickel Mine in South Africa processes one of the world’s hardest ores in a 375k TPM autogenous grinding circuit. The plant employs an unconventional processing circuit, comprising a primary autogenous mill (AG or FAG) and pebble crushing circuit followed by a secondary hybrid pebble/ball mill and classification cyclone cluster.Advanced Process Control (APC) or Expert Control is now generally accepted as an advantage in most modern high capacity concentrator grinding circuits. This paper reviews the installation of model predictive control at Nkomati and examines the results and benefits of installation in an autogenous mill during plant ramp-up. The paper also demonstrates how predefining process control objectives together with good plant and supplier cooperation can achieve a robust and reliable APC implementation on a very short site program.The results conclusively demonstrate operational and economic benefits during circuit operation with the advanced process control system ON. Production performance and circuit stability were significantly better than during manual control."

Jan 1, 2012

By Anuj Narang

Large-scale separation or flotation cells, used in the primary extraction in the oil sands industry, are integral parts of the overall process of bitumen extraction. Good regulation of the interface level between the bitumen froth and the middlings in these cells can result in a significant improvement in bitumen recovery and throughput, and heavily influence process economics. Automatic control of such industrial processes presents challenges such as multi-phase flow dynamics, variable process gain and time delays, poor quality of measurements and significant disturbances. This paper details a case study application of development of multiple models of the dynamics of the interface level and the design of model predictive controllers (MPC) for a separation cell process. A Model predictive controller (MPC) using linear models is designed and implemented in real time on an industrial separation cell. The industrial implementation results show that the MPC scheme provides significant benefits over the current operations which use a PID controller. The benefits include significant reduction in the variance of the interface level resulting in higher bitumen recovery and smoother downstream operation plus energy savings due to reduced underflow pump speed.

Sep 1, 2012

By A. W. Khair

Surface subsidence is a phenomenon mainly associated with longwall mining, although it can also occur if the coal pillar left to protect the surface deteriorates with time and results in the collapse of the room and pillar system. A method has been developed that utilizes physical mine models and laser holographic interferometry. This method is capable of measuring displacements as small as 5 micro- inches by means of generating displacement contours on a surface, even that of granular materials. Analysis of subsidence in room and pillar mining using models of various extraction ratios ad overburden depths along with two different types of overburden model material (sand and gelatin) has been made. The sand represented the extreme brittle conditions of geologic material while the gelatin represented visco-elastic behavior of geologic material. This paper deals with the analysis of data which has been gathered up to date, and mainly associated with the use of sand as an overburden model material. The analysis included the effect of variation of geometric parameters on surface subsidence. Among these parameters are: variation in seam depth and thickness, surface and seam inclination, and extraction ratio.

Jan 1, 1984

The Boliden Aitik concentrator in Sweden processes 2,000 tph of low grade copper ore. The plant consists of five grinding lines feeding four bulk flotation banks with a scavenger concentrate regrind mill, and a column cleaner circuit with a regrind mill. The authors installed a model-based expert, optimizing control system to maximize copper recovery in the bulk flotation circuit while maintaining an appropriate copper grade in the cleaner feed. The optimizing control system uses on-line assays and calculates and implements set points for cell pulp levels, air rates and reagent addition rates. It combines the power of a dynamic population balance model which estimates mineral liberation in each stream, an optimizer which computes appropriate set points and a rule-based module which implements the strategy. The benefits have been evaluated over three months. The model-based expert, optimizing control system generates a measurable increase in copper recovery, around 0.5 per cent and an optimized bulk concentrate grade. The need to maintain the optimizing control system and other practical aspects are discussed.

Jan 1, 1998

By Sushanta Majumder

The physico-chemical characteristics of raw materials used for the production of iron ore pellets have a strong influence on the productivity of pelletization operations and on the quality of pellets. Since iron ores from different sources are used for making iron ore pellets and since the quality of the ores varies with time, there is a need to optimize and control pellet plant operations on a regular basis to achieve optimum productivity while maintaining pellet quality within the desirable specifications. In order to achieve this objective, a model-based on-line optimization system was implemented on two industrial scale induration furnaces. The optimization system consists of a rigorous mathematical model of the induration process, a model for the permeability of the bed of pellets, a statistical model for the quality of iron ore pellets and an optimization module based on sequential quadratic programming. The rigorous model is tested on-line using the wind-box temperature available real-time. The process was optimized to enhance induration furnace productivity for the given constraints on pellet quality parameters such as the cold compressive strength (CCS) and Tumble Index (TI), and other equipment design parameters. Process variables such as induration machine speed, cold air flow rate and hood temperature profile were used as the optimization variables. The on-line optimization system was successfully implemented in two industrial induration furnaces and lead to enhanced productivity. Details of the on-line optimization system and results of process optimization will be presented.

Sep 1, 2012

By Alexandre Bellegard Farina

O sistema MgO-NiO é um dos importantes sistemas para o entendimento das reações metal-escória na elaboração das ligas de à base níquel. As ligas à base de níquel usualmente apresentam adições de magnésio com o intuito de melhoria da plasticidade destas o que permite o seu processamento através de processos de conformação mecânica. Neste trabalho foi realizada a modelagem termodinâmica deste sistema utilizando o modelo de células de Kapoor-Frohberg-Gaye e o módulo PARROT® do pacote Thermo-Calc® com objetivo de complementar o banco de dados SLAG®. Como resultado foi obtido um conjunto de parâmetros termodinâmicos que descrevem as fases deste sistema.

Aug 17, 2017