Search Documents

By R. Raitani

Five kaolin crudes from the state of Georgia in the U.S. were investigated for processability with chemically enhanced magnetic separation (CEMS) technologies developed by Cytec. The technologies used magnetic reagent alone or in conjunction with specialty chemicals to selectively agglomerate and magnetize the desired minerals (impurities) to be removed by the conventional magnetic separation equipment. All crudes indicated treatability using CEMS. Results indicated that CEMS technology could be applied to different kaolin crudes to obtain a product with titanium impurities less than 0.6% TiO2 from individual crudes. The features and benefits of the technologies were also reviewed.

Feb 1, 2012

By H. EI-shall

In this paper, the results of bench scale testing of five different flotation processes to separate dolomite from phosphate are discussed. The effectiveness of each process interms of phosphate recovery and MgO content in the concentrate is used together with the reagent consumption as the basis of comparison. The water quality is found to play a major role in the performance of these processes. Effect of water hardness as well as other parameters are discussed.

Jan 1, 1995

By J. Pancher

"Stainless steel castings are used in abundance in the mineral processing industry. In rotary kiln-based processes, these castings are typically exposed to high loads, corrosive elements, mechanical abrasion and cyclical temperature exposure. In the processing of iron ore pellets, it is typical to use a traveling grate preheater or a straight grate furnace to heat the pellets. Both machines have a conveyor that is mainly comprised of high temperature stainless steel castings. It is these castings which are the focus of this study. The expected life of these castings can be quite short, their cost quite high and the effort to replace them very labor intensive. The goal of this study was to gain a better understanding of the failure modes of these castings. With that basic understanding, modifications to the alloy content could be made to achieve a new operational paradigm. That paradigm could be a cheaper casting, a longer lasting casting or a casting tailored to special operating conditions (for example, highly corrosive gases or sudden temperature shocks). Over the past 4 years, Metso Minerals has sought to achieve a better understanding of the failure modes through modeling, laboratory testing and sampling of used castings from various end-users. In addition, we have tested new alloys in a laboratory setting and also in the field to see how they would perform compared to the existing ""standard casting"". Our testing has revealed interesting data concerning the impact toughness, sigma phase content and formation, chloride attack and other performance attributes of various grades of stainless steel when exposed to cyclical temperatures. Interesting results were also obtained concerning the addition of rare earth elements (Niobium, Boron, etc), nitrogen and manganese to a typical ASTM A297 grade of stainless steel. To date, a few hundred test castings have been installed in iron ore pellet plants worldwide. Many of these test castings have already experienced a year or more of operation with good results.INTRODUCTION Cast stainless steels (ASTM A297 and similar) are a main constituent used in the construction of iron ore pelletizing equipment. A typical straight grate pelletizing machine would contain upwards of 160,000lbs of ASTM A297 Grade HH castings. With a typical casting lasting only two to four years, and a casting costing around $35USD, it is easy to see that the castings are a main contributor to the overall cost of producing the pellets. Grade HH and HI (see chemical composition listed below) became the “go to” materials in the 1960’s and very few changes have been made to this day (the exception being plants that switched to flux pellet production in the 1980’s)."

Jan 1, 2015

By K. V. Raj, VASU GANGRADE

Airflow in large-opening stone mines is largely dependent on the natural ventilation due to the large cross- section area of the opening. The openings of such stone mines are typically twice or thrice the size of typical underground coal or metal/nonmetal mines. Due to the influence of natural ventilation, air velocities as well as the static pressure drop in the mines are low. Mines rely on auxiliary fans to ventilate active faces to reduce contaminant exposure to mine workers. The National Institute for Occupational Safety and Health (NIOSH) is conducting research on ventilation of large-opening stone mines to reduce worker exposure to dust and other contaminants such as diesel particulate matter (DPM). In order to reduce worker exposure to dust and DPM, an understanding of the airflow pattern due to auxiliary fans in the mine is needed. Under this research, NIOSH researchers are exploring the computational fluid dynamics (CFD) modeling to understand the airflow behavior in large-opening mines. In this paper, the team is presenting the results from three-dimensional CFD modeling of airflow in a large-opening stone mine and investigating the effect of a fan placement with the movement of trucks.

Feb 1, 2025

By D. C. Lynch

While silica ores are generally considered to have little value, those with exceptionally low B and P content have, potentially, significant worth if processed for use in photovoltaics. The sales value of a cubic meter of ?run of the mill? silica sand is $42 per cubic meter (retail and delivered). If the silica sand can be used to produce solar silicon, its value after processing is $34,000 per cubic meter. Factors that impact the suitability of silica for direct processing in production of photovoltaics are examined.

Jan 1, 2010

Little knowledge is available that considers the effects of continuous miner position on the possible respirable dust exposure of the remote mining machine operator. Such information could be very useful for increasing the awareness of the remote operator as to those parts of an extended cut that generate higher levels of respirable dust. This data could be used to develop guidelines for positioning the remote operator to reduce his potential exposure. This work details the effects of continuous miner position on dust levels measured on the machine and at the remote continuous miner operator location.

Jan 1, 1998

By R. G. Reddy

Spent potliner is generated in the electrolytic process of reducing alumina to make aluminum metal using molten fluoride electrolytes. Spent potliner (SPL), obtained at the end of the pots life contains a small amount of cyanide and fluoride which present environmental problems. SPL became a listed hazardous waste under RCRA (K088) in July, 1990. One of the possible uses of spent potliner is as a substitute for Calcium Fluoride (CaF2) as a fluidizer in iron-and steel making and in the glass industry. A low viscosity and a low melting point are prime requirements for accomplishing the above. In the present study, viscosity measurements were performed. Effect of various additives, such as sand, limestone, dicalcium silicate dust, and MgO baghouse dust on the viscosity of SPL was studied. The results showed that with the addition of sand and limestone, very high fluidity of SPL melt can be obtained at significantly low temperatures. The results suggest that spent potliner mixed with additives could potentially be used as a substitute fluidizer.

Jan 1, 1999

By Reece Kurre, Gabriel Walton

"Roof bolting has long been used in underground mines across the world to provide ground support. Modern roof bolts are cheap and easy to install with the use of specialized machines as a part of the production cycle. Lhoist North America’s Crab Orchard Mine is an underground room and pillar limestone mine that uses mechanically anchored roof bolts for ground support. The mine currently employs two different roof bolting patterns: a standard 5 × 5 foot pattern, and a 2.5 × 2.5 foot pattern for use in areas with particularly hazardous roof conditions. The purpose of this study is to evaluate the relative effectiveness of each bolting pattern.A series of numerical models were created using RocScience’s RS2. The models were based on a symmetrical section of the mine at its deepest point, and were modeled using Generalized Hoek-Brown failure criterion along with a discrete fracture network. A series of sensitivity analyses were performed on the models by varying parameters such as joint friction angle, crack persistence, joint randomization, and tensile strength of the limestone. Based on the results of the original models and sensitivity analyses, it appears that the standard bolting pattern provides sufficient roof support capacity under almost all the expected conditions at the mine, since factors of safety below the design value of 1.5 were only found for individual bolts in a few of the worst test cases considered. These results can help improve the Mine’s productivity and reduce operating costs without compromising safety.INTRODUCTION AND CASE STUDY DESCRIPTIONLhoist North America’s Crab Orchard Mine is an underground limestone mine located in Crab Orchard, Tennessee. The mine is located under an 800-foot-high mountain, and outcrops on three sides. The mine is accessed through three separate portals and has two main levels, along with a partially developed third level. Extraction is accomplished by the room and pillar method using 50 × 50 feet pillars and 50 × 50 feet rooms. The mining height is limited to 50 feet to keep the pillar width to height ratio around 1.0. Each heading is excavated in a two-stage process that consists of a 30-foot-tall top heading and a 20-foot-tall bench. A distance of at least 30 feet is maintained between the two levels at all times (Crab Orchard Mine Technical Staff, 2017)."

Jan 1, 2019

By C. E. Jordan

The Bureau of Mines investigated a simultaneous elutriation and flotation technique for separating polyethylene terephthalate (PET) from polyvinylchloride (PVC). The Tuscaloosa Research Center, through a cooperative agreement with a recycling company, devised an elutriation-flotation method for beneficiating the mixed heavy plastics portion of municipal solid wastes which is composed of polystyrene (PS), PET, and PVC. A sodium carbonate brine was used to remove the lighter PS from the heavier PET and PVC. Over 98 pct of the PS was recovered in a high purity PS concentrate containing 99.7 pct PS, The remaining PET and PVC mixture was washed to remove the brine salts that would be harmful to the flotation process. The clean PET and PVC mixture was conditioned in a solution of 45 g/t gelatine and floated in a short (l-m) column flotation cell in an upward flow of water. In a single flotation step, over 75 pct of the PET was recovered in a high purity product containing 99.8 pct PET. The bubbles attached to the PET lowered the effective density of the PET-bubble agglomerate and allowed successful separation of these agglomerates from the PVC plastic pieces. This method separated two-thirds of the mixed plastics fraction into high purity PS and PET products suitable for recycling and left only one-third of the plastics in the mixed plastics product.

Jan 1, 1992

By R. Benemelis

The existence of resins in some coal deposits in various parts of the world has been known for many years. These resins vary considerably in chemical structure and properties. The resin that is found in Utah coal, however, is rather unique, and has properties particularly attractive for the manufacture of printing ink mastics and adhesives. This resin is a rather dark, very high melting point, low molecular weight hydrocarbon resin. Its typical properties are shown in Table I. Its largest use by far, has been in the printing ink industry. The history of Utah coal resin is interesting, but unfortunately one of disappointment and failure.

Jan 1, 1990

By Daniel A. Payne

For many years underground mining in the Sydney Coalfield has suffered from the effects of high horizontal stresses. It is only in the last 15 years that they have come to be recognized, understood, predicted and even avoided. This paper relates experiences in three coal mines in three different seams in the Sydney Coalfield. The effect of the direction of the principal horizontal stress on the direction of drivage of gate roads, access roadways and longwalls is described. Results of a monitoring program to measure the change of magnitude and direction of the principal horizontal stress in the gate roads as a result of longwall mining are also presented as well as the effect of the direction of principal horizontal stress on the shape of sandstone/gas outburst cavities.

Jan 1, 1998

By George E. Edwards

Pacific Rim markets for export coal already represent a larger market than the total tonnage imported into the European Community countries and they will continue to expand. The largest importers will continue to be in the sector comprising Japan, Korea, Hong Kong and Tai- wan. It is likely that the total Pacific Rim markets will reach 206 m.t.p.a. by 1990 and 290 m.t.p.a. by 2000, with the major growth in steam coal demand. Australia has an efficient coal industry, represents a stable long term source of supply and is favourably situated geographically to continue to be the largest single supply source.

Jan 1, 1982

By S. Makni, F. Wang, A. Rosa, B. Klein, C. Saud, R. McIvor, A. Kumar, C. Gagnon, D. Gong

In response to the Natural Resources Canada “Crush It Challenge”, Corem partnered with the University of British Columbia and led a project to develop and demonstrate the use of high-pressure grinding to replace the workhorse of the industry, wet ball milling, with high-pressure grinding. Two plant case studies, a small tonnage gold recovery operation, and a large tonnage copper recovery operation, were carried out. Plant circuit performances were compared to pilot plants operated on the same circuit feed set up to represent the novel equipment and flowsheet that was developed to produce separation circuit feed. Numerous obstacles to industrial implementation of highpressure grinding in this role which were recognized at the outset of the work were successfully addressed. In both cases, comminution equipment energy savings alone, and final stage total circuit energy savings, exceeded 60% and 50%, respectively. Downstream mineral separation performance was the same or better.

Mar 2, 2022

By Suresh K. Bhatt

A mathematically simulated modeling technique is used in this U.S. Bureau of Mines paper to represent a hypothetical mining operation with existing mining technology and prevalent mining costs. Mining scenarios are prepared and evaluated for potential benefits and costs available through computer-assisted mining. Base criteria, parameters, and methodology are described.

Jan 1, 1991

Microorganisms have been widely used for hydrometallurgical operation and effluent treatments(Smith, et. al., 1991a; Gadd, et. al., 1986; Darnall, 1986; Paponettis, et. al., 1991; Mihaylov, et. al., 1991; Rusin, et. al., 1991; Noble, et. al., 1991; Yang, et. al., 1991). In recent years there is a growing interest in using microorganism for flocculation of minerals fines and flotation collector (Smith, et. al., 1991b, 1991c; Misra, et. al., 1991a, 1991b, 1992a, 1992b). It is envisioned that the utilization of nonpathogenic microorganism and/or extracellular surfactant derived from microorganism as a flotation collector will replace some of the environmentally toxic flotation collectors and at the sometime improve flotation efficiency. The selection screening, and judicious selection of appropriate microorganism as flotation collector has been a challenge to process engineers. Over the past five years, continued research at the University of Nevada has shown that certain microorganism Mycobacterium phlei (M. phlei) can be a good flocculating agent and has potential to be used as a flotation collector (Dubel, et. al., 1992; Misra, et. al., 1991a, 1991b, 1992a, 1992b; Smith, et. al., 1991d; Chen, et. al., 1992a, 1992b)).

Jan 1, 1993

By J. Y. Kim

Lead ions originating from galena during processing of complex sulphide ores migrate to "cover" the surface of sphalerite and iron sulphide mineral particles, and cause poor selectivity in differential flotation. Generally in sulphide ore processing, the lead-activated minerals float in the Cu/Pb rougher circuit. Subsequently, surface lead complicates the zinc flotation circuit by lowering the concentrate grade due to the co-flotation of lead-activated iron sulphide minerals. The effect of lead in the differential flotation of sphalerite from Cu-Pb-Zn and Pb-Zn ores is discussed. Plant and laboratory test data are interpreted by determining the surface composition of individual grains of sphalerite and iron sulphide particles using two surface analytical techniques, Laser Ionization Mass Spectrometer (LIMS) and Time of Flight-Secondary Ion Mass Spectrometer (TOF-SIMS). Cationic and anionic species on the surface were analyzed to elucidate the phenomena.

Jan 1, 1995

By G. K. Hoffman

Humate, defined as weathered coal or mud-stone rich in humic acid (HA) and fulvic acid (FA) have been mined, primarily as soil amendments or drilling mud additives, in New Mexico for 15-20 years. The New Mexico humate resource is estimated to be 11 Gt, including weathered coal and organic mudstone. The HA and FA content determines the end-use, therefore a simple and consistent method of measuring organic-acid content was developed. The New Mexico Bureau of Mines and Mineral Resources method is based on repeated alkali leaching and acid precipitation. Precipitates of humate are ashed, with mass balance of solids maintained, to correct for material added during alkali-acid treatment. Analyses of upper coal member, Cleary Coal Member (Menefee Formation) and Fruitland Formation samples from the southeast San Juan Basin show ashing to be important in accurate analysis of FA content. Ash in the total FA fraction averages 70% compared to 2% in HA. The FA in weathered coal and organic mudstone are similar, although HA is significantly higher in the former. As weathering progresses, the FA content of weathered coal increases faster than in organic mudstone because of the greater total organic material in coal.

Jan 1, 1994

By M. Deutsch

A common casualty of modern open pit mine optimization is the assurance that the resulting design is actually achievable. Optimized mine plans that consider value and a bare minimum of precedence constraints do not, in general, translate into practical, operational mine designs that can really be used in the field. Ultimate pits may come to a sharp point at the bottom. Schedules may require taking small parcels of material from many disparate areas of the pit in a single period. And grade control polygons may be ragged, narrow, and not minable with realistic equipment. In this paper all of these problems are addressed by encoding these three fundamental open pit mine optimization problems as maximum satisfiability problems. Maximum satisfiability provides a useful framework for problems that are non-linear and may guarantee the optimality that metaheuristics cannot. INTRODUCTION Open pit mines are large and complicated operations, which require significant initial and ongoing investment. A single mine may employ hundreds or thousands of people and creates substantial benefits for both the surrounding and global communities. Planning an operation of this magnitude requires a lot of effort and cannot be done optimally by hand. Mining engineers today rely on many techniques from operations research to guide decision making, and to maximize the value of the mine. Techniques including linear programming, metaheuristics, and network algorithms are all used to solve different problems throughout mine design and optimization. However, techniques based on Boolean satisfiability, including the optimization extension of maximum satisfiability, have not seen much use in mining despite being used in many other fields including electronics design, scheduling, and artificial intelligence. We claim that maximum satisfiability is a useful and meaningful way of expressing and solving optimization problems in mine planning. However, this technique does not come without challenges; the problem is NP-hard, and modern techniques for solving these problems can struggle with the number of variables and clauses that a typical mining problem requires. Also, some of the constraints that mining must contend with do not fit nicely into the satisfiability paradigm. Despite these challenges, we believe that maximum satisfiability provides a useful framework for considering operational constraints and expressing some problems that other techniques can't easily express. Maximum satisfiability can be solved exactly, yielding the true optimal answer which metaheuristics cannot guarantee. In this paper we show the applicability of maximum satisfiability to mining by specifying three fundamental problems in open pit mine optimization. We show how these fundamental problems can be formulated and how they can be extended within the framework of maximum satisfiability. For the remainder of the paper we first give a brief background on common elements between the three problems and an introduction to satisfiability. Then we tackle the three problems; the Ultimate Pit Problem, the Block Scheduling Problem, and the Grade Control Polygon Problem. In the Ultimate Pit Problem we specifically show how to extend the problem to support a minimum mining width – a coveted result for many mining engineers. We then discuss some of the complexities and shortcomings of this framework and possible research directions.

Jan 1, 2019

By R. P. King

The MODSIM mineral processing plant simulator is used to find optimal combinations of target separation specific gravities in a typical modem coal washing plant. A plant that is set up with these optimal targets can deliver up to 10% more yield at the same ash content as the same plant set up with separation targets chosen by conventional methods. MODSIM is the only simulator currently available that can simulate the liberation of pyrite and other mineral matter during open-and closed-circuit grinding operations. The simulator can therefore be used to assess the benefits of grinding operations in the flowsheet.

Jan 1, 1997

By G. A. Parkison

The sequential copper analysis method is a particularly useful technique to semi-quantitatively define the geologic, mineralogic, and metallurgical types and zonations commonly associated with porphyry-type copper deposits. The method is based on the partial dissolution behavior displayed by the prevalent copper minerals malachite, chrysocolla, chalcocite, and chalcopyrite to solutions containing sulfuric acid and sodium cyanide. Results from sequential analyses of the sample and analytical residue using sulfuric acid followed by sodium cyanide and then aqua regia solutions when compared with conventional total copper analyses can determine the amounts of leachable oxide minerals, leachable secondary sulfide minerals, and primary copper minerals, respectively. Sequential assay analytical results and interpretation are presented for copper deposits in Chile, Mexico, and the United States.

Jan 1, 1995