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By M Lak, R Amiri, A Haratian, M Asghari, S Haji

In recent years, due to advances in designing of various magnet assemblies, a wide range of magnetic materials with different properties can be concentrated. Jalal Abad iron ore beneficiation plant, which is located in Iran, Kerman province, is currently producing iron ore concentrate with the capacity of 0.8 Mt/a by having medium intensity magnetic separators (MIMS) with rougher and cleaner stages that finally leads to the production of an iron concentrate with the Fe grade of about 65 per cent. In this plant, the rougher tailings directly goes to the thickener as the final tailings and cleaner tailings feeds to the ball mill for regrinding. Since some hematite particles with weak magnetic properties cannot be recovered from only these two stages of magnetic separation, the obtained tailings from this concentration plant has approximately an iron grade of 25 per cent to 27 per cent. Accordingly, laboratory processing tests were conducted on the obtained representative sample of the final tailings. Based on the experimental results performed on final tailings, a new magnetic drum separator with a specific magnetic assembly was designed that could finally lead to product with iron grade range of 58 per cent to 60 per cent with relative and total weight per cent of 8.6 per cent and 3.86 per cent. Finally, it could be concluded that feeding of magnetite particles to the existing drum separators, due to their high magnetic field intensity, cannot efficiently lead to improvement of the grade of concentrate. Therefore, pilot magnetic separation tests were done on the final concentrate for evaluation of product upgrading probability. Consequently, by increasing another stage of cleaning and by decreasing the magnetic field intensity, the final product grade could be enhanced from 65 per cent to 67 per cent.

Nov 8, 2021

By Robin Schott

The blast furnace process is the most important process to produce pig iron. The necessary process energy is mainly covered by coke. But the production of coke is connected with CO2-emissions and high costs. A significant measure to reduce the coke rate and with it the CO2-emissions plus costs is pulverized coal injection (PCI) through the tuyeres into the blast furnace. A further increase to substitute coke by coal can be achieved by using the Oxycoal+ technology. This article compares and shows the cost effectiveness and the decrease of CO2-emissions with the help of simplified energy balances for the only coke operation of the blast furnace, the operation using pulverized coal injection and the operation using the Oxycoal+ technology.

Aug 17, 2017

By M. Rotz

In the minerals industry today, the ?low hanging fruit? that once existed to debottleneck production and improve recovery, while meeting market needs for quality in mineral processing operations, are more and more difficult to find. Systematic methods for establishing plant mass flow, recovery, operational efficiency and control strategy in context with customer specifications provides the necessary insight and confidence for plant operators to prioritize improvement projects in order to maximize return on investment (ROI) for the site. The evaluation of aggregate and industrial mineral processing plants requires the following steps when projecting cost saving opportunities: collecting background data, conducting a base-line evaluation, analyzing specific unit-operation performance, defining investment options, prioritizing the selected improvement opportunities and the implementing process changes. The following paper describes the approach and challenges of developing an improvement plan for a dry and wet mineral processing operation.

Feb 23, 2014

By A. B. Holland-Batt

Two graphical techniques which are commonly used to assess batch separations are analysed in terms of reaction kinetics to provide a more powerful method of evaluation. An alternative and more general approach, based on the selection and application of suitable efficiency criteria, is also presented. The method proposed distinguishes between selection and collection efficiency in flotation and can be used to estimate the degree of liberation in the feed. Two examples are given: table concentration of monazite and ilmenite from a beach sand, and flotation of a pyrite-haematite ore

Dec 1, 1971

With the signing of the armistice on Nov. 11, the direction of the main concentration of effort of the United States was changed. In order to win the war, all industrial efforts had to be organized and centralized. With the war won and peace in sight, this centralization of effort stopped and the full play of individual initiative was allowed to resume its sway in the community. During this period of reversal of direction of effort, there was a natural loss of momentum and the United States, as well as the rest of the world, is in for a period of readjustment. The immense progress that was made in one direction under the stress of the necessities of war, which focused the energies of a nation in one direction, is an outstanding example of what can be accomplished if a community with many varying interests can be united on one objective which it desires to attain. The realization that the fusing of many interests into one stream of effort is difficult should not prevent us from taking the long view ahead that is necessary in order to be able to measure the progress made. If we don't have a mountain peak to guide us, we are very likely to run in circles in the plain without reaching the goal to which we strive. The most efficient development of natural resources is an ideal that, from a material point of view, appeals to the engineer. This ideal includes giving of opportunities to everyone to take a share in the development of these resources.. It also contemplates rewarding foresight

Jan 4, 1919

By Marlies Grimmer, Frank Amo Boateng

One of the challenges of mining is the concentration of heavy metals it releases into the environment through a phenomenon called Acid Mine Drainage. Freiberg is no exception due to its long mining activities. The European Union proposes that all rivers and streams must be in a good ecological status by the year 2027 but this would be difficult for large water sources as it would be economically unviable. Consequently, the approach of treating these waters at point sources would be of immense help and hence this column experiment on mine water treatment with carbon sorbents to remove zinc form the Rothschönberger Stolln. For this experiment three resins namely, APTsorb, activated coke, charred fermentation residues (which was produced by the Freiberg University of Mining and Technology) were analyzed through a simple column experiment to determine their sorption capacities. Through their sorption capacity as this experiment seeks to ascertain: we are able to make suggestions scientifically on the best material among the three for the future design of a treatment plant for the RSS. After the experiment whereby a 10 ml peri glass column was used, material A: APTsorb showed the least adsorption capacity (0.01 meq/g) and this could be attributed to the fact that the resin works well under pre-determined parameters such as pH and surface area. Material B: Activated coke showed a better sorption capacity (0.53 meq/g) in comparison to the basis value used for this experiment. Material C: charred fermentation residue which was produced by the University showed the most efficient capacity of (1.69 meq/g). This in comparison with the value used as the basis for this experiment showed that material C (charred fermentation residue) is very efficient for zinc sorption. pH values measured at the effluent of all the experiment were slightly higher than the pH measured in the initiating water.

Feb 1, 2024

By S. Shi, J. Y. Hwang, B. Li

Silver, copper, and zinc are commonly known elements with antibacterial and antifungal capabilities. Attempts have been made to dope silver on minerals, glass, and ceramics and the resulting materials have been investigated for their antibacterial and antifungal properties. Since silver is expensive and very reactive, silver doped materials have been found inappropriate in some applications. Copper-vermiculite is investigated as an alternative. Vermiculite has high cation exchange capacity on the magnesium ion in the crystal structure. Copper ion may have a high tendency to replace magnesium because of similar charge interference and ionic radius. Copper-vermiculite is prepared by reacting vermiculite and copper chloride solution. By impregnating copper ions into the nanometer openings between the layers of vermiculite, it is possible to render the composite with antibacterial functions if the copper ions could be released gradually from the composite. The antibacterial efficiency of Cu-vermiculite against Escherichia coli was studied using the Halo method. The results show that Cu-vermiculite is effective for preventing the reproduction of the bacteria. Heat treatment of Cu-vermiculite at up to 400°C does not show significant changes in antibacterial activities.

Jan 1, 2002

By A. Kogelbauer, A. Stadtschnitzer, A. Boehm, F. Schillab

"The paper covers the design and implementation of an industrial dense medium cyclone plant for carbonaceous iron ore, the proving of efficiency as well as the development of a predictive model for plant control. The VA Erzberg GmbH mines about 12 Mio.t of carbonaceous rock ore at the “Steirische Erzberg”. Due to increased demand of the Austrian steel plants, the production of ore concentrate was raised by 30 % up to 3.0 Mio t/a during the last 5 years. One of the projects to realize the increase in capacity at improved concentrate quality was the implementation of a dense medium cyclone plant for the fine size fraction – 8 +1 mm replacing the former dry permanent magnetic drum separators. By physical separation the siderite variety “spateisenstein” (42% Fe) of a density of 3,8 g/cm³ is separated from ankerite (10 – 17% Fe), the second iron bearing carbonate with a density of 3,2 g/cm³, dolomite, calcite and silicate bearing schists. The feasibility of the process was proven by the test results obtained from a test rig, that was constructed and operated in close cooperation between the Chair of Mineral Processing, Montanuniversitaet Leoben and VA Erzberg GmbH. The density separation surpassed the efficiency of magnetic separation clearly shown by •- values. The plant performance tests (capacity 120 t/h) verify the cut densities defined by Tromp T50 -values and the assigned efficiency found in the pilot tests at varied settings of media density, pressure drop, cone angle and apex diameter. The test rig as well as the final process will be presented. In order to create a tool to predict the performance of the DMS in the centrifugal field at various settings for varying feed composition the experimental results from size and density testing are analyzed in a modified way to obtain physically justified, smooth approximations for the performance curves. Models developed on coal washing plants are checked for their validity at increased densities."

Jan 1, 2018

By J. R. Sims

Gold assays from production blastholes in the Mercur Hill Pit were used to delineate known ore zones and to determine how well previous exploration drilling defined these zones. The most important factors causing inadequate ore zone definition were: 1) inappropriate location of drill holes relative to the ore zones, 2) presence of stopes from previous mining, 3) sampling and assaying errors, and 4) smoothing of the ore zone boundaries during ore reserve estimation. Infill drilling strategies were evaluated to determine the efficiency with which a given drill pattern defined the known ore zones. A drilling strategy was developed which improved ore zone delineation when compared to techniques which maintained uniform drill spacing.

Jan 1, 1992

The standard procedure of fire refining consists of sulphur removal via air injected through tuyeres, arsenic slagging via soda-lime flux and oxygen reduction by air or oxygen deficient air or a steam fuel mixtures. The use of porous plugs to stir with an inert gas has been mainly considered as a surface renewing agent that increases the product quality and shorten the refining cycle. In the present study the effect of the bottom stirring by nitrogen gas injection through porous plugs for the treatment of the crude copper in the range of 400-150 ppm sulphur, 3,000-2,000 ppm arsenic and 14,000-7,000 ppm oxygen content was investigated. The combined effect stirring-reducing, by the use of air or a steam fuel mixtures through tuyeres for oxygen removal, follows a kinetics of first order where the constant, K, can be represented by the following polynomial expression: K = A * R2 + B * R + C Where A, Band C are constants that depend on the nitrogen flow rate and R is the air-fuel ratio or the steam-fuel used in the reducing step. Depending on the optimization of the flow of nitrogen and the air-fuel or steam-fuel mixture and only if just the oxidation, complexing and reducing steps are considered, the process cycle might be shortened by 45%.

Jan 1, 2003

By C. Acuna

The standard procedure of fire refining consists of sulphur removal via air injected through tuyeres, arsenic slagging via soda-lime flux and oxygen reduction by air or oxygen deficient air or a steam fuel mixtures. The use of porous plugs to stir with an inert gas has been mainly considered as a surface renewing agent that increases the product quality and shorten the refining cycle. In the present study the effect of the bottom stirring by nitrogen gas injection through porous plugs for the treatment of the crude copper in the range of 400-150 ppm sulphur, 3,000?2,000 ppm arsenic and 14,000-7,000 ppm oxygen content was investigated. The combined effect stirring-reducing, by the use of air or a steam fuel mixtures through tuyeres for oxygen removal, follows a kinetics of first order where the constant, K, can be represented by the following polynomial expression: K = A .* R2 + B * R + C Where A, Band C are constants that depend on the nitrogen flow rate and R is the air-fuel ratio or the steam-fuel used in the reducing step. Depending on the optimization of the flow of nitrogen and the air-fuel or steam-fuel mixture and only if just the oxidation, complexing and reducing steps are considered, the process cycle might be shortened by 45%.

Jan 1, 2003

By J. B. Austin

IN considering so complex a process as the smelting of iron in the blast furnace, there is obviously no single method of calculating efficiency that gives a complete appraisal of the performance of the furnace in all its several functions; such a comprehensive view as is required to evaluate producing ability and manufacturing costs for a given furnace is obtained only by considering a group of efficiencies, each of which measures the performance of the furnace from a specific point of view. For instance, there is the rate of consumption of coke per ton of iron produced, which is probably the most frequently considered, and is certainly one of the most important of the group; there is the efficiency of recovery of iron charged; and there is the efficiency of utilization of energy, both chemical and thermal, in some respects related to the former two yet in other ways independent of either. In each of these cases, the calculation can be made on the basis of the actual input of material or energy, or it may be based . upon a comparison with the minimum amount of material or energy that would be required by a "perfect" furnace; that is, an imaginary ideal furnace analogous to the perfect steam engine used in thermodynamic calculations, when this furnace is operating under optimum conditions. Moreover, the furnace itself can be considered either as an apparatus for smelting iron or, taking a somewhat less common point of view, as a gas producer yielding iron and slag as by-products. Some of these effi-ciencies are more useful than others, yet all are instructive; for a knowl-edge of them not only leads to good engineering practice from the standpoint of control but also discloses limits to possible improvement in performance and indicates the lines along which improvement is most likely to be profitable. Estimates of some of these efficiencies have appeared from time to time in the literature, but many of them are open to objection because they are based on data of uncertain accuracy or because they have been calculated without due regard to the thermo-dynamic principles involved. Moreover, so far as the author is aware, no general survey of the blast furnace comparing its performance in all the aspects mentioned has been made.

Jan 1, 1938

By D P. Obeng, L Reemeyer, R Holmes

The Zinifex Century Mine employs a large number of Detritor mills for fine and ultra-fine grinding to liberate silica and sphalerite at 80 per cent passing 7.5 microns before final zinc flotation. A joint project between CSIRO Minerals and the Zinifex Century Mine was carried out to evaluate the Detritor mill performance. Plant surveys were conducted around the Detritors in conjunction with laboratory tests. The survey data showed that the Detritors in the ultra-fine milling circuit performed well. They reduced a feed F80 sizing of 46 microns to a product P80 sizing of 7.5 microns at a gross energy consumption of 37.2 kWh/t. Scale-up of ultra-fine milling Detritors was studied using a 0.55 kW laboratory batch unit and a 355 kW full-scale Detritor by processing Century zinc concentrate with 1 mm sand media. The results indicated that the 0.55 kW laboratory mill underestimated the energy consumption of the full-scale Detritor by about 20 per cent for a product P80 of seven microns. The performances of a horizontal IsaMill and a vertical Detritor were compared as ultra-fine milling devices for processing Century zinc concentrate. The experimental data demonstrated that, when using the same grinding media, the energy efficiency of the two mills is similar despite the difference in mill designs. The Detritors used for regrind duty at the Century Mine performed poorly when processing feed at 80 per cent passing 88 micron. The energy consumption was high and the product size distribution was broad with particles above 100 microns in the feed unbroken and particles below ten microns overground. A coarser ceramic media of 3 mm was therefore tested in a laboratory Detritor to process the regrind Detritor feed as an alternative to the 1 mm Colorado sand used at the Century Mine. The ceramic media reduced the energy consumption significantly and produced a narrower product size distribution, which is more desirable for the downstream flotation process.

Jan 1, 2007

By M. Gao

The Zinifex Century Mine employs a large number of Detritor mills for fine and ultra-fine grinding to liberate silica and sphalerite at 80 per cent passing 7.5 microns before final zinc flotation. A joint project between CSIRO Minerals and the Zinifex Century Mine was carried out to evaluate the Detritor mill performance. Plant surveys were conducted around the Detritors in conjunction with laboratory tests. The survey data showed that the Detritors in the ultra-fine milling circuit performed well. They reduced a feed F80 sizing of 46 microns to a product P80 sizing of 7.5 microns at a gross energy consumption of 37.2 kWh/t. Scale-up of ultra-fine milling Detritors was studied using a 0.55 kW laboratory batch unit and a 355 kW full-scale Detritor by processing Century zinc concentrate with 1 mm sand media. The results indicated that the 0.55 kW laboratory mill underestimated the energy consumption of the full-scale Detritor by about 20 per cent for a product P80 of seven microns. The performances of a horizontal IsaMill and a vertical Detritor were compared as ultra-fine milling devices for processing Century zinc concentrate. The experimental data demonstrated that, when using the same grinding media, the energy efficiency of the two mills is similar despite the difference in mill designs. The Detritors used for regrind duty at the Century Mine performed poorly when processing feed at 80 per cent passing 88 micron. The energy consumption was high and the product size distribution was broad with particles above 100 microns in the feed unbroken and particles below ten microns overground. A coarser ceramic media of 3 mm was therefore tested in a laboratory Detritor to process the regrind Detritor feed as an alternative to the 1 mm Colorado sand used at the Century Mine. The ceramic media reduced the energy consumption significantly and produced a narrower product size distribution, which is more desirable for the downstream flotation process.

Jan 1, 2007

By V. K. Karra

An improvement in the present day screen sizing methods calls for knowledge on i) how material in the size range: 0.5 x 1.5 times the through-fall opening of the mesh on a deck, splits between the oversize and undersize streams of the deck, and ii) how near-mesh content of the feed affects the screening performance. In the throughput based sizing method given here, this is accomplished through the introduction of a generalized partition curve and a near-mesh factor. A newly developed efficiency factor is employed in addition to the traditional screen sizing factors.

Jan 1, 1979

Efficiency, Economics, Energy and Emissions - Emerging Criteria for Comminution Circuit Decision Making

Sep 13, 2010

By GLENVILTE A. COLLINS

(Presented at a Meeting of the Spokane Local Section of the Institute, Feb. 17, 1912, and accepted for publication in the Bulletin. ) WHILE I am not at the present time engaged in active mine-management, my duties permit of extensive study and examination of many mines, mills, and reduction-works in various places throughout the United States. Being much interested in efficiency-work in general, and an ardent reader of writings on this subject by Frederick W. Taylor and others, as applied to manufacturing-plants, and having served my apprenticeship from mucking to the engineering design of ore-dressing and underground plants, I hope that this paper will lead others to investigate the field more fully, to the improvement of general mine- and mill-operations, as well as the advancement, intellectually, physically, and financially, of the employee and his relations with the employer. If a man who is prepared to look closely and observe broadly starts in Canada and zig-zags from camp to camp to southern Mexico, taking time casually to inspect mines, mills, and smelters, he will be pitifully impressed by the great difference in customs, and the general waste of labor, time, and money throughout the country. He will so seldom observe a dollar's worth of results given in exchange for a dollar spent that he will form a poor opinion of operating-efficiency and management. This highly-scientific department, requiring an amount of skill and executive ability equaled in few, if any, of the professions, certainly falls short of the standard established in our greater manufacturing industries. It is easily said that this is due to the diversity of conditions in mining, milling, and smelting. But on second view it must be admitted that there is room for tremendous improvements in nearly every mining-organization. The proposal of such improvements is often met by the argument that any mine

Sep 1, 1912

By Jorge Cárdenas, Gustavo Huerta, Regina Rocha Oriundo, Miguel Angel Humpire, Johan Salas Flores

Currently a critical activity for slopes stability and safety in mining is pre-split blasting to reduce damage from trim blast. Most common explosive used are based on packaged explosives, with 1 ½ in diameter cartridges initiated by detonating cord. Traditional loading process requires a significant amount of trained personnel, which in our application context could take up to 20 blasters. When pre-split blast is scheduled, it usually reduces the availability of the blasters on the total loading services at site which are also demanded to have production blasting ready at same 12-hour shift daylight time.

Feb 6, 2023

By Javier Illanes Pizarro, Gustavo Huerta Valer, Jorge Cárdenas Miranda

Bench stability is the basis of sustainability in an open pit mining operation. Taking care of the pit walls while maintaining fragmentation results can prove a challenge. In this study, technical proposals have been developed for extra hard rock mass (UCS>175MPa) with presence of unfavorable structural planes in high copper grade zones. The base case shows low compliance of fragmentation results and a significant loss in berm width, with over size boulders causing low primary crushing rates. Paradigms in current drill and blast design were overcome to improve fragmentation results and achieve objectives.

Feb 6, 2023

By Justin Lukens, Di Stasim Jeffrey, Frank Di Salvo

Columbia University’s Manhattanville Campus expansion includes the construction of two new business school buildings. The new buildings require development of an entire city block bound by 12th Avenue, W 131st Street, W 130th Street and Broadway in Upper Manhattan. A support of excavation (SOE) package was first released, followed by a foundation package. The SOE package consisted of approximately 100 soldier piles and 280 anchors, up to 215’ long, to support a cut anywhere from 30’- 50’ below street level. The foundation package alone included approximately 1600 drilled micropiles. Given the breadth of the work scope, Hayward Baker Inc and Moretrench joint ventured on these two projects to bring sufficient knowledge and work resources to complete the work in an efficient and timely manner. This included working with the Owner/Engineer to propose different means and methods for construction to significantly reduce the schedule while meeting the design intent, such as large diameter (36” diameter) augercast piles in place of conventionally drilled soldier piles and large hollow-bar micropiles (103/51 bars) in lieu of pressure-grouted micropiles. The anchors, ranging from 3 to 22 strands, were used for earth retention through both soldier pile and lagging walls and existing slurry walls. These anchors were complicated based not only on their size and length, but also the need to drill some of them under the historic Studebaker building. The overall magnitude of the project with considerations to resource management and material lead times will be addressed, highlighting critical strengths provided by the Contractor to ensure project success. The scope of work discussed in this paper was executed under two separate competitive bid contracts. The first contract included the support of excavation work and the second contract included the foundation package. The support of excavation comprised of drilled soldier piles (performed by Case Foundation as a subcontractor to the JV), driven soldier piles, driven sheet piles, hollow bar tiebacks, multi-strand tieback anchors and micropile soldier piles. The foundation package consisted of drilled micropiles. Due to the large scope of work and critical schedule requirements of the project, the JV had to think outside the box and present value engineered alternates to expedite installation durations.

Jan 1, 2019