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By M. F. McCarty, R. S. Olson

New organic flocculants of high-molecular weight are replacing lime, glue, and starch in liquid-solid separation. Of these synthetic materials, poly-acrylamides are outstanding. Polyacrylamides form a class of compounds varying widely in composition and activity. Separan 2610, one of the first of these flocculants' released to the mining industry in 1954, is described' as a high-molecular weight polymer of acrylamide with or without a copolymer material and with some replacement of amide by carboxylic groups. MECHANISM OF FLOCCULATION In practice, flocculation makes solids settle faster and filter better. But two opposing factors control it. The random motion that causes particles to collide favors Van der Waals' forces, which hold the particles together. The effect of zeta potential opposes this contact, and particles are mutually repelled. Flocculation can be achieved by reducing the magnitude of the zeta potential; this is the mechanism of flocculation by lime addition. The way in which polyacrylamides accomplish flocculation is not fully understood, but the action is undoubtedly comp1ex and probably varies considerably depending on the system. To begin with, the active groups of these compounds have an extremely high affinity for solid surfaces, probably by hydrogen bonding." Initially some active groups of the molecule attach themselves to the solids with a large portion of the molecule extending into the solution. Two particles can become tied together by long flocculant molecules in the following ways—by bonding between the active groups of two flocculant molecules on different particles, or by an extended molecule from one particle attaching itself directly to the surface of the other particles." These flocculant bridges prevent the particles from moving apart through random motion, but when such motion moves them together other active groups on the flocculant bridge bond to the solids, holding them in the closer position. This process is repeated until the particles are close together. Although bridging is probably a major flocculation mechanism, it is not the only phenomenon involved. Relatively neutral acrylamide flocculants reduce the magnitude of the zeta potential by increasing the viscosity of solution in the immediate vicinity of the solid surface which contains the mobile counter ions of the double layer. In other words, it moves the shear surface which bounds the zeta potential out into the solution containing counter ions which tend to neutralize the zeta potential. This effect is probably more pronounced during the initial adsorption period, before the flocculant molecules are pulled close to the solid. In some cases the slight charge of the polyacry-lamide molecule tends to neutralize a zeta potential. However, this is not a primary flocculation mechanism, as evidenced by the fact that the polyacrylamides will flocculate solids with either positive or negative zeta potential. Adsorption of polyacrylamide flocculants by a solid is substantially an irreversible reaction. Since the flocculant molecule is attached to the particle surface by many active groups of high bonding strength, desorption would require the simultaneous breaking of many bonds—an unlikely occurrence. UNIQUE PROPERTIES The irreversible adsorption of certain polyacrylamides, the flocculant's high affinity for solid surfaces and its rapid adsorption make it effective, but these unique properties require special techniques to achieve maximum flocculation. If flocculants of this type are added to a pulp as a relatively concentrated solution, the solids in the

Jan 1, 1960

By E. S. Porter

The techniques of particle-size measurement are of particular importance in the manufacture of portland cement. A range of sizes, from a close approximation to Fred C. Bond's "theoretical infinite" (represented by raw material in the quarry) to particles smaller than one micron is represented in the process. Moreover, similar size-reduction operations are performed on both natural and synthetic materials, the former relatively inactive in water and the latter quite reactive. This means that aqueous sedimentation systems for particle-size analysis are applicable only to some of the materials involved in the process. A brief review of the process should be useful to place the measurement techniques described here in perspective. (Fig.l) Raw materials are quarried, crushed and transported to storage at a maximum size usually of a few inches. Typical materials are limestone and clay or shale, with small amounts of other materials used to adjust the plant mix to the concentration of lime, silica, alumina and iron oxide required.

Jan 6, 1962

By N. Naude, W. P. Roux

Fine particle beneficiation plays an ever-increasing role in mineral processing plants and it seems that technology can’t keep up with the challenges involved in the treating of these fines. The REFLUX™ classifier has proven itself able to treat high tonnages of fine material, especially in the coal industry. There are various fine ore applications that can benefit from such a process, yet laboratory and pilot-scale tests on many of these ores show poor efficiencies and recoveries. A better understanding of the design, operation and mechanisms of the REFLUX™ classifier is required to determine if and how it fits into these applications. The mechanisms in gravity separators are very complex due to the complex hydrodynamics, and the REFLUX™ classifier is no exception. The mechanisms of these systems are usually described through theoretical single particle-models that are hard to verify through analysing the feeds and products of these processes. To verify these models the movement of individual particles must be measured, which is not an easy task. In this paper the separation mechanisms in the incline channels of the REFLUX™ classifier were investigated with high-speed videography. A small lab scale model of the incline channel was constructed for this purpose. It was possible to capture and track the trajectories of particles under certain conditions and match these trajectories with theoretical models. The resuspension of particles, clustering and streaking was also observed and captured. Keywords: REFLUX™ classifier, particle trajectory, beneficiation, high-speed videography

Jan 1, 2020

Mineral sand beneficiation plants comprise a complex combination of electrostatic, magnetic and gravity based separation techniques. These are combined and replicated in ways that provide the most efficient and cost effective separation of the valuable components. On line instrumentation has been developed at the JKMRC (eg. conductor/non-conductor(CNC) ) to measure the properties of the dry plant process streams. This paper provides results from the recent development of a novel low cost mass flow meter and discusses their combined use with the CNC instrumentation for the control of dry separation circuits.

Jan 1, 2003

By Klinefelter G

The United States Steel Mining Co., Inc. recently experienced a major mine fire at the Cumberland Mine. This mine is located in Greene County, Pennsylvania, U.S.A. and is mining a high volatile bituminous coal seam (Pittsburgh Seam). The mine fire was success- fully controlled and extinguished without loss of life or serious injury to any miner or mine rescue personnel and finally reopened within 40 days of its inception.

Jan 1, 1988

By W. D. Roberts

INTERGRANULAR corrosion of metals and alloys has been extensively investigated and the current conclusions are summarized in the Symposium on Stress-Corrosion Cracking of Metals.' It appears, however, that the relative importance of the various factors involved in the mechanism is still obscure. Several recent, independent studies, in combination with available X ray data op preferred orientation, indicate that there may be a direct correlation between relative orientation of contiguous grains and susceptibility to intergranular corrosion. The object of the present note is to show the nature

Jan 1, 1951

By M. D. Johnson, R. K. Bezys

"The majority of Ontario's limestone and dolostone production comes from a few Paleozoic carbonate units. In eastern and central Ontario, Ordovician rock units, which are the main sources for production, include the Oxford, Gull River, Bobcaygeon, Verulam, and Lindsay Formations. They are predominantly utilized for aggregate and cement manufacturing, with the Bobcaygeon Formation being used as a source of building stone. Along the Niagara Escarpment, the Silurian Lockport, Amabel, and Guelph Formations are sources for the limestone industry. The largest tonnage of rock extracted by the industry comes from these Silurian units, especially the Lockport and Amabel Formations. These units are used primarily for aggregate, although they are also a source for lime. In southwestern Ontario, the Silurian Bertie Formation and Devonian strata, represented by the Bois Blanc Formation, Onondaga Formation, Detroit River Group, and Dundee Formation, contribute to Ontario's production of lime, cement production and crushed stone. The Detroit River Group (Lucas and Amherstburg Formations) is the main source of the lime and cement produced in the province.Northern areas, which may become significant sources for the industry, include Manitoulin Island, the Lake Timiskaming area, and the James Bay Lowland. IntroductionThe Engineering and Terrain Geology Section of the Ontario Geological Survey has undertaken a geological inventory of all active and abandoned limestone and dolostone quarries in Ontario. This geological study, combined with a commercial study of active quarries carried out by the consulting firm of Derry, Michener, Booth and Wahl, will provide an up-to-date report on the industry in the province and will be published by the Aggregate Resources Section of the Ministry of Natural Resources. This report will follow the format and style of D.F. Hewitt's Ontario Department of Mines Industrial Mineral Reports and Circulars (Hewitt, 1960, I964a, 1964b, 1964c; Hewitt and Vos, 1972). Examinations of the quarries were carried out by geologists in the Paleozoic I Mesozoic Geology Subsection of the Engineering and Terrain Geology Section, and include, in addition to the authors, R,R. Wolf, V.A . Mazur, and D.K. Armstrong in the summer of 1986."

Jan 1, 1988

By Alan A. Campoli

The U.S. Bureau of Mines evaluated two different conventionallongwall gate entry systems in the Southern Appalachian Basin, where mining and geologic conditions are conducive for coal pillar bumps. These gate entry systems were in a coal mine located in the Pocahontas No.3 Coalbed under approximately 2,000 ft of overburden and a massive quartzite sandstone member, and both employed a center abutment pillar flanked by yield pillars. The 8O-ft-square tailgate abutment pillars within the first study area began bumping 500 ft in advance of mining. This was accompanied by face bumps on the tailgate corner of the longwall face. The 120-by 180-ft tailgate abutment pillars within the second study area did not begin to bump until mining was approximately 100 ft past. Coalbed stress change and abutment pillar dilation data demonstrated that a 15-ft-wide perimeter of yielded coal surrounded a highly stressed core in both sizes of abutment pillars. The 62 pet more core area per foot of gate entry in the larger abutment pillars prevented excessive load transfer to the corner of the tailgate panel and eliminated the face bumps experienced with the original gate entry design.

Jan 1, 1990

By G. M. Bernard

Cerro Colorado lies on the eastern edge of the Atacama Desert in the foothills of the Andean Cordillera of northern Chile. Compañía Minera Cerro Colorado SA (CMCC) operates Cerro Colorado. CMCC, headquartered in Santiago, Chile, is wholly owned by Rio Algom Ltd., of Toronto, Ontario. Cerro Colorado is located 120 km (75 miles)east of the port city of Iquique. Access is by 30 km (19 miles) of paved highway and 70 km (43 miles) of upgraded road. The mine site is located at an altitude of 2600 m (8531 ft) on a gentle west-sloping plateau adjacent to a deep canyon (Quebrada de Parca) to the north. Temperatures are moderate, ranging from 5° to 30° C (41° to 86° F) with an average annual rainfall of 20 mm (0.8 in.). The plateau is generally covered with 20 to 30 m (65 to 100 ft) of Quatemary sand and gravel overlaying bedrock. In the immediate vicinity of the Cerro Colorado deposit, a semicircular embayment has been eroded into a steep canyon wall that cuts through the surface gravels to expose a considerable section of the underlying bedrock.

Jan 1, 1995

By J J. Cilliers

The aim of this paper is to give an overview of the FrothSim flotation simulator and to demonstrate its ability to predict the performance of real flotation circuits. Example simulations are presented in which the feed rate to the circuit is varied, followed by simulations in which a cleaner section and recycle loop are added to the rougher bank.The simulator is able to predict both the recovery and the grade produced by the cells at all locations in a circuit and the simulator is shown to produce plausible grade recovery curves. It also demonstrated that the performance of banks of cells improve as the feed rate to the bank increased (improved grade for a given recovery), but that more cells are required to give the same overall recovery.

Jan 1, 2005

By John Ralston, Gayle E. Morris, Daniel Fornasiero

The interaction of talc with carboxymethyl cellulose, a polymeric depressant currently used in the mining industry, was investigated. adsorption isotherms, infrared spectoscopy and microflotation studies were performed to determine the surface properties of the depressant at the talc-water interface. Solution conditions were varied in ionic strength, pH and the presence of magnesium ions. The adsorption of the anionic polyelectrolyte, carboxymethyl cellulose onto the talc surface was greatly influenced by the solution ionic strength and pH. Limited adsorption, and therefore depression, occurred at high and low ionic strength. Adsorption, and thus talc depression, improved greatly with either increased ionic strength or reduced pH. With the addition of magnesium ions, talc depression was shown to improve considerably. The improved depression is likely to be the result of the formation of a magnesium ion-carboxyl complex.

Jan 1, 1995

By James Lee Hibbard, Doraiswami Ramkrishna

A population balance model accounting for the transient variations in drop size distributions in a stirred liquid-liquid system is analyzed for its effect on chemical reaction conversion in a stirred, batch reactor. The analysis is applied specifically for phase transfer catalytic reactions, which indicates that transient effects of evolution of drop size distributions may be important in such systems.

Jan 1, 1981

By James A. Finch, Linda Restrepo, Mitra Mirnezami, Amy Buchanan, Maryam Hashemi

Settling rate studies on slurries from Cu/Zn flotation plants occasionally reveals two aggregation maxima at pH 8-10 and 10-12 (Figure 1). From measurements on sphalerite and silica suspensions the double maxima could be replicated. These maxima correspond to the effects of Zn and Mg ions. The aggregation mechanism of both ions is related to the formation of the corresponding hydroxide precipitate. A combination of chemical and electrostatic bridging by the hydroxides is considered to be the aggregation mechanism.

Jan 1, 2003

By Alfred H. Bell

The year 1937 has been outstanding in the history of the Illinois oil industry. During the course of the year the state's daily production has been trebled, increasing from 12,000 bbl. per day at the beginning to 37,000 bbl. per day at the end, and the year's total, 7,426,000 bbl. is 66 per cent above the previous year's production of 4,475,000 bbl. The production in January was 368,000 bbl.; in December it was 1,085,000. Production from the old fields increased slightly. Most of the new production is from fields in the central part of the Illinois Basin, an area that for many years was considered unfavorable to the occurrence of oil and gas. The principal producing horizon of the new fields is the McClosky "sand," an oolitic limestone in the Ste. Genevieve formation of lower Mississippian age. Although development has not yet gone far enough to permit accurate estimates of oil reserves in the new fields, it is believed that they are of the order of 100,000,000 barrels. The following are the oil fields discovered in 1937 listed in order of amount of daily production at the end of the year; Noble (Richland County), Clay City, including Southeast Clay City (Clay and Wayne counties), Patoka (Marion County), New Centralia (Clinton County), Olney (Richland County), Cisne (Wayne County),.Beecher City (Fayette County), and Rinard (Wayne County). One gas field, the Russellville, in Lawrence County, was discovered in 1937. For locations of the new fields see Fig. 1. A generalized geologic column for Illinois, showing producing horizons in the new fields, is given in Fig. 2. The total productive area of the new fields at the end of 1937 was 1712 acres, in which 230 wells were producing. Thisrty-five dry holes were drilled within 1/4 mile of producing wells. At the end of the year there were 19 drilling wells, 28 rigs standing, 18 rigging up and 4 new locations in these fields. In the whole state 447 wells were completed, of which 284 were oil producers and three gas producers. Total initial daily production of

Jan 1, 1938

By Wilfred G. Comeao

Close-in blasting occurs every time the use o f explosives for excavation or demolition requires the surpassing of the commonly accepted cosmetic damage criteriain order to arrive at reasonable and practical explosive weights per delay. One of the many effective blast design procedures consists in establishing a reasonable charge weight per delay with respect to scale, geometry, costs, requirements and constraints of the project. Once this reasonable charge weight per delay is determined, it’s environmental effects have to be estimated with respect to the surroundings.

Jan 1, 1991

By A. Pranowo, G. R. F. Alvear F., N. Aslin, M. S. Moats

"The toxicity of arsenic is well known and documented; however, the presence of arsenic in copper electrorefining anodes and electrolytes is critically necessary to produce high-quality cathode. Arsenic as well as antimony and bismuth concentrations vary relative to their concentration in the anode copper received from the smelter. The behaviour and benefits of arsenic in copper electrorefining and the detrimental effects of antimony and bismuth on cathode quality and tankhouse performance are discussed. This will include the minimization and mitigation of problems associated with arsenic, antimony, and bismuth—including cathode contamination, floating slimes, scaling, and anode passivation.RÉSUMÉ La toxicité de l’arsenic est bien connue et documentée; toutefois, la présence d’arsenic dans les anodes de l’électroaffinage du cuivre et dans les électrolytes est d’une nécessité critique pour produire une cathode de grande qualité. Les concentrations en arsenic, ainsi qu’en antimoine et en bismuth varient selon leur concentration dans l’anode de cuivre reçue de la fonderie. Le comportement et les avantages de l’arsenic dans l’électroaffinage du cuivre et les effets indésirables de l’antimoine et du bismuth sur la qualité de la cathode et le rendement des cuves d’électrolyse sont discutés. On traite aussi de la minimisation et de l’atténuation des problèmes associés à l’arsenic, l’antimoine et le bismuth – incluant la contamination de la cathode, les schlamms flottants, l’entartage et la passivation de l’anode."

Jan 1, 2016

By Khosrow Ebrahimi

We document the occurrence, mineralogy and firing properties of magnesite from hydrothermal deposits in the upper Cretaceous ophiolites of Eastern Iran. These deposits occur as thin veins of nearly pure cryptocrystalline magnesite with only trace amounts of quartz, calcite, and dolomite. Ratios of CaO/SiO2 in the bulk ore are variable. The composition of dead-burned magnesite from these deposits, calcined at different temperatures and durations, is predictable from phase equilibria. Textures of the calcined magnesite were studied by SEM; results show that the principal impurites produced during calcination are forsterite, monticellite, merwinite, dicalcium and tricalcium silicates, and that these are located principally at triple junctions of the periclase crystals. The size of periclase crystals increased with temperature and duration of calcination and the amount of periclase-periclase grain contacts was reduced by increasing the concentration of impurities in the starting products. EPMA show: 1) that CaO and FeO contents in periclase increase steadily with an increase in the CaO/SiO2 ratio and the FeO content of the bulk ore, respectively, and 2) that limited solid solution exists between impurites. This study demonstrates that high quality dead-burned magnesia refractories can be produced from the Iranian magnesite with low CaO, SiO2 and FeO contents.

May 1, 2004

By Vincent P. Gi. ccnella

GOLD was discovered in Gold Canyon on May 15, 1849. Following this discovery placer miners worked the gravels in the canyon for-ten years, finally discovering the outcrop of the Comstock lode at Gold Hill in May, 1859, and in Ophir ravine on June 12 of the same year. Before long large quantities of gold and silver, were taken from the lode and one of the West's most spectacular mining booms drew thousands of fortune seekers to Nevada. After a long period of production activity waned and in late years little mining was done. The recent reopening of the old mines and the discovery of ore in other parts of the vein, and in other veins of the district, has led to a revival of interest in the Comstock. Virginia City, Gold Hill, and Silver City, situated along the great vein system, are enjoying a period of prosperity and a large influx of people.

Jan 1, 1934

By F. Gordon Smith

ALTHOUGH several geological indicators of the critical type are known, including quartz inversions and decomposition of hydrous minerals such as serpentine, there are very few of the general type. Solid solutions are excepted, but the limitations of use are very restricted and interpretations are sometimes ambiguous. General methods for determining temperature and pressure conditions during the crystallization of minerals would have considerable scientific and economic value. It is not the purpose of this paper .to, discuss the various methods of geological thermometry and barometry, but to present one general method, applicable to all minerals, and to describe what progress has been made in the methods of measurement. The general method, in. brief, is a study of the stress conditions in and around various types of foreign inclusions which are trapped in minerals during growth. The method depends upon the fact that any homogeneous gas, liquid, or solid will in general have coefficients of thermal expansion and volume compressibility different from those of any given mineral. Therefore stress must develop in and around all types of inclusions in minerals if the temperature or the pressure, or both, are changed from the conditions which prevailed during the growth of the mineral. The methods of measurement consist of determinations of the temperature-pressure conditions of fit of the inclusions in the host mineral. The types of inclusions in minerals are: 1-gas, or liquid plus vapor, when observed at room temperature, due to crystallization under pneumatolytic conditions; 2-liquid, or liquid plus vapor when observed at room temperature, due to crystallization under hydrothermal conditions; 3-glassy solid, or devitrified glass, due to crystallization under magmatic or high temperature metamorphic conditions, in a siliceous liquid; and 4-crystals, due to overgrowth of other minerals crystallizing simultaneously or of other minerals which crystallized previously. A survey of the literature shows that much valuable earlier work on inclusions, especially that carried out in England in the last century, has dropped out of current knowledge. The following is a brief summary of the significant, contributions to the problem up to the present day. Davy in 1822 asserted that fluid inclusions in minerals consist of an aqueous solution of salts and a gas bubble, the whole being either at lower or higher pressure than atmospheric.1 At intervals from 1823 to 1862, Brewster contributed information concerning other types of inclusion consisting of 1-aqueous solution, a much more expansible liquid, and a gas; 2-aqueous solution, salt crystals, and a gas; and 3-the very expansible liquid and a gas. The very expansible liquid fills the gas space between 20° and 30°C. Compression strain effects were seen around inclusions in diamond, topaz, and other minerals.2-6 Sorby in 1858 and 1869 further advanced the study begun by Davy, stating that fluid inclusions represent a sample of the mother liquor of crystallization and that the degree of filling of aqueous inclusions at room temperature defines the temperature-pressure relations during formation of the host. The degree of filling may be measured by determining the minimum temperature of filling of the inclusion by the liquid phase. The very expansible liquid in some fluid inclusions is liquid. carbon dioxide. The temperature at which salt crystals in fluid inclusions completely dissolve in the fluid is the minimum temperature of formation. Inclusions of glass or devitrified glass indicate crystallization from a melt. Inclusions of crystals in minerals are often centers of strain, which may be seen by optical effects or by radial tension cracks. Sorby realized that an analysis of stress-strain relations about inclusions could be used to provide precise data on the temperature of crystallization, but the matter was never pursued.7,8 Hartley (1876, 1877),9,10 Hawes (1881),11 Wright (1881),12 Johnsen (1920),13 and Holden (1925)14

Jan 1, 1952

By James F. Howe

EveRy engineer and user of wire rope is desirous of information that will enable him to determine whether the performance of any particular piece of rope is satisfactory, and what conditions can be changed so as to increase the life of a rope. In most cases, it is far from easy to analyze the conditions of service and tell which is the greatest factor in determining the life of wire rope. If we start on a layout for an entirely new rope system, the task of making conditions satisfactory is simplified so far as the engineering details are concerned; but if the plant requiring wire rope is in operation, any change is likely to involve the expenditure of considerable money to replace and change over machinery that must be kept in constant operation, because a large monetary loss will result from a shutdown for even a few days. Often wire rope is kept operating under bad conditions, as the user thinks that it is cheaper and quicker to replace the rope than to make alterations in the hoisting machinery. A typical case is a metal mine operating in what is now almost the center of a large mining city, where it owns a few acres of mineral rights. It was expected that the shaft would go to a depth of 1000 ft. (305 m.), so a moderate-sized rope, about 1 1/4in. (31.7 mm.), was used on a 6-ft. drum with a 7-ft. head-frame sheave and rather short lead from drum to head sheave. This mine has gone deeper each year until it is now 2500 ft. deep and the rope speed has been increased from 1500 ft. per min. to over 3000 ft. The original rope just filled the drum in one layer, now it overwinds three layers. The original ropes were probably 6 X 19 crucible steel and lasted from 12 to 18 mo.; now, the highest grade plow steel is used, yet the average service is only about 6 mo. The cause is not hard to find. If the engineers had known at the outset what would be done with this hoist, the design would have been very different. Conditions at this mine, from a wire-rope standpoint, have gradually become worse and it is difficult to see how rope service on this hoist can be compared with the service of previous years with any fairness to the wire-

Jan 1, 1923