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By B. Oraee-Mirzamani

One the most important tasks after excavation of tunnels is the implementation and installation of a support system. Tunnel collapse poses a safety hazard and can cause worker injuries. In addition, it may have a severe economic impact because tunnel collapse can stop production and ore transportation. Therefore, an appropriate and well-designed support system is necessary for collapse prevention and to help stabilize the tunnels. In this research, we suggest a support system for the Parvade1 underground coal mine. The study case is a common mining roadway tunnel in the E1 longwall panel in this mine. To design an appropriate support system, we used the finite element method (Phase2 software). The results of this research can be used to design support systems for future tunnels in this mine and any coal mine that has similar conditions.

Aug 1, 2013

By Francois Charette

Corrosion is a significant factor affecting the capacity and working life of ground support. The paper explores a relatively simple method to predict the load capacity of a support system using a Monte Carlo stochastic approach. The analysis uses published field data on existing ground support to evaluate the applicability of the method and its predictive performance. Discussion on corrosion rates found in the field and predicted from laboratory measurement is provided.

Jun 1, 2012

By S. H. Castro

Molybdenite depression by shear degraded polyacrylamide solutions has been investigated. Aqueous solutions of polyacrylamide-type flocculants were subjected to shear degradation under a range of high-speed stirring conditions. Settling tests, carried out with quartz slurries and sheared polyacrylamides, showed reduced flocculant performance with increased degradation. As the sedimentation rate is strongly dependent on the polymer's molecular weight, these results fit well with the shear degradation theory, which predicts the production of shorter chain segments due to breakage of the polymer macromolecules. Microflotation tests on natural molybdenite showed that the depressing ability of a commercial polyacrylamide flocculant remained unaltered after shear degradation, even when the flocculating ability was entirely lost. Practical implications of shear degradation on molybdenite flotation are discussed.

Jan 1, 2004

By J. Drelich

We report structural forces measured for 10 nm silica particles deposited on alumina substrate and 5-80 nm alumina particles on mica using atomic force microscopy technique. For nanoparticles forming clusters, oscillation of structural forces was recorded with a periodicity that is close to the size of the nanoparticles used. Additionally, selected force-separation results indicate that the forces involved between the AFM probe and individual nanoparticles can be studied using the nanoparticle-coated substrates.

Jan 1, 2006

By K. Niboucha, M. Zergoug, S. Brick-Chaouch, H. Houali

"Corrosion is an electrochemical process that causes degradation and deterioration of various steel works (pipelines, drains, cisterns) whether they are buried, immersed, or not. Worldwide, we estimate that corrosion destroys a quarter of the annual production of steel at a rate of 5 tons per second. Several techniques are used to protect against corrosion. Among these processes, Cathodic protection, which is regarded as the best technique to assure the protection of steel, works against this phenomenon. This is achieved either by a system of reactive anodes, or by the technique of impressed current protection or other techniques. Before any installation of cathodic protection, a preliminary study and pre-evaluation of certain parameters must be made. In the present work, we will present an example of dimensioning of an installation of cathodic protection by imposed current of a pipeline using solar energy, where we discuss the following items:•,Evolutions of the potential as well as current along the pipeline and their respective expressions deduced from the laws known as telegraphists;•,Range of protection (potential of protection along the pipeline);•,Influence of the isolation resistance of the coating on the range of protection;•,Effect of the aging of the coating and its influence on the current of protection."

Jan 1, 2005

By William C. Browning

An economic drilling programme is one which costs the !east in chemicals, equipment, and time. The basis for such a programme with rotary drilling techniques is a drilling fluid in which bentonites do not swell. This is recognized in the growing trend toward gyp and other inhibited mud systems. Therefore, even though the mechanism of thinner action is a subject of applied colloid ,chemistry, the understanding of this mechanism is of economic importance in controlling the flow properties of inhibited muds. In phosphate, or sodium tannate, conditioned muds that are relative-!y free of contaminating-electrolytes, the thinner, or dispersing agent, is adsor.bed, ?creating an electrical double layer about the clay particles. The mutual repulsion of these charged particles effects colloidal stabilization, or deflocculation of the suspended clays, as discussed by Norton and others. In inhibited muds, however, the electrolyte concentration in the filtrate is sufficient to collapse the double layer and flocculation of the mud solids occurs, as evidenced by increased viscosity and gel values. Chemicals to control the flow properties of inhibited muds, therefore, are vital to the successful use of these systems as it is not always economical to adjust flow properties by watering back. Flocculation of suspended particles, as indicated in the work of Vervey, Overbeek, and others, is due primarily to gravity-like, long-range Van der Waals forces. Prevention of flocculation may, therefore, be secured by the interposition of any barrier between the particles, the thickness of which approximates the extension of the Van der Waals at-traction. Organic polyelectrolytes, such as Kembreak, Rayf!o, and Q-Broxin, may act to increase the double layer charge when used in small amounts in fresh-water muds. More important, however, is the fact that in inhibited muds an increase in concentration of the polyelecholyte permits the formation of a condensed film adsorption layer of the polyelectrolyte about the clay particle. When this occurs, the extremely viscous condensed adsorption layer creates a mechanical. barrier that prevents flocculation of clays, even in the presence of inhibiting concentrations of elecholytes. Rheological evaluation of the degree of deflocculation, or colloidal stability, may be made by utilizing the known effects of particle inter-action and volume concentration on the flow properties of suspensions. Rheological evaluation should be supplemented by direct microscopic or ultra-microscopic observation.

Jan 1, 1958

By A. Alfantazi, L. Choudhary

Gold leaching in thiosulfate solution has attracted widespread research interest through the last two decades primarily due to its perceived environmental benefits in comparison to the conventional gold cyanidation technique. However, the data on the corrosion and/or corrosion-induced failures of plant infrastructure materials in the solutions relevant to thiosulfate gold leaching are very limited. Accordingly, this study aims to characterize the electrochemical corrosion behavior of stainless steel 316L in the thiosulfate gold leaching solutions. Electrochemical corrosion response was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy. The morphology of corroded specimens was analyzed using scanning electron microscopy.

Jan 1, 2014

By W. G. Hatch

Introduction Classified equipment originally installed in 1923 in the Britannia mill consisted of eighteen Model C Dorr Simplex classifiers, each in closed circuit with a pebble-mill. These machines were only three feet wide and of light construction, so that their raking capacities were necessarily limited, the maximum being about 20 tons per hour for each classifier. On conversion from pebble-mills to ball-mills, in 1924, attempts to increase circulating loads with higher rake speeds resulted only in overflowing a coarser product to the flotation cells. The elevator type of classifier was developed locally in 1935 and during that year two units, each having a sand carrying capacity of from 30 to 40 tons per hour, were installed. With such loads, a material increase in the grinding capacities of the ball-mills was noticed, and, after further development work on the elevator classifier, fifteen of the small Dorr classifiers were replaced by units of this type, capable of handling approximately 75 tons of sand per hour, with later alterations increasing this capacity to well over 100 tons per hour. In the meantime, the three remaining ball-mills had been placed in circuit with Dorr FX classifiers, one of which was six feet wide and the others five feet wide. Impartial and exhaustive tests conducted on the Dorr FX versus the elevator classifier showed the average results on these machines at Britannia to be substantially the same. A large amount of testing was carried on to determine the effect of circulating load on the output of the grinding units. This work indicated a rapid increase in the grinding rate as the ball-mill feed increased up to about 60 tons per hour, after which a relatively slow increase took place up to 100 tons per hour. No benefits were derived from higher circulating loads. A 300 to 500 per cent circulating load, depending on the nature of the ore treated, is considered to be within the economical range for the grinding of Britannia ores.

Jan 1, 1946

By Richard P. Taylor, Rod Henham

Abstract - Newly discovered pegmatites distributed throughout the sub-surface environs of the Musselwhite Archean gold deposit occur as narrow dikes that intrude most of the major lithological units. The mineralogy and textures of the pegmatite dikes are characteristic of granitic pegmatites of the "Rare-Element Class"; more specifically, they closely resemble varieties of the "Complex-type" granitic pegmatites that are commonly associated with zones of tantalum mineralization. The essential minerals in the dikes comprise albite, quartz, and K-feldspar, together with lesser amounts of mica (including lepidolite), spessartine, tourmaline, and locally, spodumene. Fine-grained (30 µm to 300 µm), tantalum-bearing minerals occur in the quartzo-feldspathic matrix of the dikes as disseminations, in interstices, and in small vugs. The nature of the tantalum-bearing mineral assemblage present in individual pegmatite dikes varies from a simple mineral assemblage composed of ferrocolumbite (with around 39 wt% Ta2O5) in the most northerly dike, to more complex assemblages comprised of manganotantalite (with up to 75 wt% Ta2O5), ferrotapiolite (with up to 79 wt% Ta2O5), and microlite (with up to 76 wt% Ta2O5) that are present in dikes located several kilometers to the south and southwest. The compositional characteristics and textural relationships of the tantalum-bearing minerals in the dikes provide evidence of igneous fractionation trends that are typical of rare-element granitic pegmatites. Such trends suggest that the newly discovered pegmatites represent part of a more extensive group of cogenetic, tantalum-mineralized dikes.

Jan 1, 2001

By Giles St. Pierre

"The purpose of this paper is to report in a general way on the use of the Portaspec X Ray Spectrograph.At Manitou Barvue, we are milling two types of ores, copper and zinc. The control assay practice was to take grab samples at 4 hour intervals. These samples were dried in the mill, then taken over to the Assay Office where two operators would process them. Three hours later results were available at almost the same time as the operator was ready to take his set of grabs again, leaving no time for adjustments, if any were needed.After a reduction of personnel, there were no assays available on night shift. This practice was slow and inadequate, and a new way of doing control assays was investigated.After investigation the Portaspec was found suitable for the type of operation that we had in mind. The Portaspec is a conventional dispersive type of X Ray spectrograph. The instrument consists of three parts:The Power Supply The Spectrographic Head The Digital ScalerIn our case, where dried powder samples are analyzed, the instrument was provided with a two sample holder using one for the standard and the other for the sample. The operation of the instrment does not require any degree of skill or knowledge of chemistry or spectrography.Previous to buying the instrument, six sets of six to ten samples were sent to the supplier along with the assay for each sample. These samples were Cu. HDS., Cu. Conc., Cu. tls, - Zn. HDS., Zn. Conc., Zn. tls. A definite pattern was observed. For example - six Cu. HDS. samples ranging from .40 to .90 gave 10400 counts for the lowest to 16.040 counts for the highest. The number of counts were then plotted to give percentages."

Jan 1, 1971

By J. E. Dutrizac, R. J. C. MacDonald, J. B. O'Reilly

"Sometime around 3000 B.C., primitive metallurgists working in the mountainous regions of Asia Minor bordering on the Black Sea (Pontus) produced a soft, easily fused metal today known as lead. It appears certain that the first metal was made by reductive smelting of galena, but whether this recovery arose by the accidental inclusion of galena in the stones of a fire hearth or whether it occurred as a consequence of simple pyrometallurgical experiments on a series of interesting ""stones"" will likely never be known with certainty. The properties of galena, high metallic lustre, great density and facile cleavage, must have excited the ancients, and such ""stones"" would have been the object of primitive testing111 - Shortly after the discovery of lead, the ancients found that the controlled oxidation of this metal at elevated temperatures yielded smaller amounts of a more interesting material, silver. Again, it is uncertain if the production of silver by primitive cupellation techniques was the result of a fireside accident or the consequence of a deliberate experiment, but the important fact is that silver was produced shortly after the discovery of lead. The techniques for making lead and silver spread gradually throughout the entire civilized world, likely as a result of both technology diffusion and independent rediscovery. The physical properties of lead could not have been overly attractive to the ancients, but silver was a different matter altogether. The gleaming white lustre and relative immunity to oxidation quickly assigned silver to the precious materials category, a status it still enjoys. In early times, argentiferous galena was inevitably processed only for its silver values; lead was generally an unwanted byproduct and was frequently discarded as litharge (PbO) during the cupellation process. The silver was eagerly sought, however, and resulted in considerable mining activity culminating in the famous Athenian silver mines at Laurium at the southern end of the Athenian peninsula."

Jan 1, 1999

By S. B. Mishra

Ni-20Cr metallic coating was deposited on a Ni-based Superalloy (3Fe-19.5Cr¬0.3Ti-Balance Ni) by a shrouded plasma spray process; NiCrA1Y was used as a bond coat. Erosion studies were conducted on uncoated and plasma-spray coated superalloy specimens using an air-jet erosion test rig at a velocity of 40 m/s and impingement angles of 30° and 90°. The coating has been characterized for porosity, microhardness and microstructure and X-Ray Diffraction (XRD). An electron probe micro analyzer (EPMA) was used to obtain X-ray elemental mappings of the coating along the cross-section. Scanning electron microscope (SEM) with EDAX attachment was used to analyze the eroded surfaces.

Jan 1, 2005

By Keith C. Hendrick

"Metal prices are frequently the most critical and least predictable element in determining the profitability of mining operations. Short -term fluctuations can be offset in varying degrees by hedging or other market actions. Such solutions are not practical for the longer term, The paper investigates the nature and extent of metal price risks and evaluates methods to reduce them.IntroductionIt is management's responsibility to improve the odds by managing the-risks by identifying them clearly, assessing them accurately, minimizing them where possible-and, then, timing decision s success fully.In determining the profitability of current operations, preparing forward plan s or developing feasibility studies for new projects or expansions, pr ices are usually the most critical input. Being market determined rather than cost based, they can also be the most unpredictable As a result, commodity prices are frequently the greatest of all risk factors.Nature of Commodity PricesThe cyclical nature of commodity prices is well known. They are stable only when supply is in balance with demand and forecast to remain that way. An imbalance on either side of the equation can lead to a price reaction completely out of proportion to the actual or perceived surplus or shortage.This exaggeration arises through the cumulative effect of market forces. When the market senses an uptrend, consumers buy for the expected increase in activity. They also seek additional quantities for inventory before price s rise. Merchants defer spot sales anticipating higher price s, speculators go along for the same reason, and producers raise prices in response to demand. Events tend to confirm the expectation of each party and strengthen their reaction causing prices to move higher."

Jan 1, 1983

By J. L. Nebreda, Z. Fan, J. B. Patel

"A380 alloy has been widely employed to produce thin-wall components via high pressure die casting (HPDC). During HPDC processing, there is a significant problem of property variation even with the very stable and precision automated casting procedure. The enlarged variation lowers the component performance and affects the steady and uniform property distribution along the whole component. In this study, high shear melt conditioning technology was developed and applied to the melt prior to pouring into the shot sleeve. Experimental results show that with application of intensive melt shearing, the variation of elongation was decreased from 21.8to 13.9%, and yield strength variation was reduced from5.5to 3.6%. The improved property variation is attributed to enhanced nucleation both in shot sleeve and the die-cavity, and to the improved distribution of porosity and secondary phases as a benefit of high shear induced grain refinement. With application of high shear, large number of the Spinel phase (MgAl2O4) particles with double size distribution in average diameter of 80and 300nm were formed. Due to the good orientation relationship and small misfit between alpha Al and MgAl2O4, the particles act as the effective nuclei in shot sleeve and die cavity, respectively.INTRODUCTIONA380 alloy had been widely used for produce automotive components by cold chamber high pressure die casting(HPDC) processing, due to its relative good mechanical properties and cast ability performance, and more important most of A380 ingots were produced by recycled Al alloys. Therefore, to promote utility of A380 will contribute to reducing emission of CO2and to the lightweight of automotive industry as well. When cold chamber HPDC was employed to produce the components, the mechanical properties of A380 alloy always have a distribution range (named variation herein), or in other words the properties were not stable. The reason was ascribed to the typical solidification characteristics occurred in HPDC processing. During HPDC processing, there are three steps of melt movement. The first step is that the melt was poured into shot sleeve at temperature of about 680°C, in which shot sleeve was preheated by few shots of melt filling, or by heater. During step one, the first solidification of melt was happened in shot sleeve and about 20% solid made of coarse a-Al grains was formed(Li, Xiong, & Guo, 2016).Such kind of grains will retain in the final products and deteriorate the properties variation. The second step is that the melt was forced moving forward slowly by plunger at about 0.2–0.3m/s until the liquid melt front to the inner gate of mold. The third step is that the melt moved very fast to complete the filling of die cavity and refilling the solidification shrinkage by fast movement of plunger about 2–3m/s. The second solidification was occurred in die cavity and fine a-Al grains will be formed by high cooling rate at about 500–1000°C/s. From the solidification point of view, the grain size was dominated by nucleation and growth. When HPDC was employed to produce components, the melt quality becomes the priority factor to control the solidification process as the other casting parameters were kept at the same."

Jan 1, 2018

By S. F. LEAMING

Jade occurs with alpine-1ype serpe111iniIes in a be// of middle Paleozoic to Triassic rocks extending from southern British Columbia in10 Yukon Territory. Most known deposiIs are in BriIish Columbia and are associa1ed wi1h the Cache Creek Group. Jade deposits are generally small len1icular masses 1ha1 lie along con1acIs beIween serpenIinites and various countIy rocks; some are 1ec1onic inclusions wi1hin se1pen1ini1es. Qualify and quan1i1y of 1he jade varies widely. Deposi1s occasionally, but rarely, reach 3,000 /Onnes. The ma1erial may be rendered non-commercial by .frac1ures, impuriIies, inferior colour and poor IexIure. Because unit value of jade can approach $80.00 per kg, greaI incen1ive exisIs 10 exploi1 1his resource. Successful commercial operations, however, depend on large- *A more detailed version of 1hi paper occur in Leaming (1978). PHOTO I . Sawn blocks of nephrite ready for shipping. 270 volume sales, for which $6.00 to $15.00 per kg is more realistic. Many undiscovered jade deposits undoubtedly remain in the Canadian Cordillera.

Jan 1, 1984

By Vilkul Yuri

Operation of the iron ore deposits of Krivbass which has been going for 130 years, has led to serious problems related to reaching great depths in open pit and underground mining. Extraction of the huge volume of rock mass (about 9 billion m3) resulted in mass violations of the natural state of the subsurface. At present most mining operations are carried out either by combined open pit and underground mining or by open pits in areas underworked by underground mining. Now the process of movement of the strata underworked by underground mines is not completed ? work fronts of open pits approach the areas of possible funnel, terrace and fissure formation, movement continue to develop. With deepening mining operations the remaining reserves are worked off under layers of incumbent rocks of > 900 m. Significant underground voids arise from mining "blind" deposits at large depths. Heaving of voids over the mined area lasts for decades; it may result in not only unpredictable time of funnel emerging and area development of movement synclines, but also the threat of air blows in mines. Forced caving of incumbent rocks as a way of controllable backfilling is difficult to achieve for economic and technical reasons. This is much more expensive and dangerous than stoping. Furthermore, the mining practice does not know examples of enormous volume backfilling under a km thick rock layer. Currently, RMI "KNU" is conducting research and pre-design work directed at creating a specialized pilot Geoinformation System (GIS) of continuous remote monitoring of rock mass in areas of underground voids influence in Krivbass area. Implementation of this system will enable to determine promptly in time and space the areas of the beyond cut off stress condition, to inform about possible occurrence of events that may result in accidents and to improve safety of mining along with other systems of forecasting and controlling the stress condition in rock mass. RMI "KNU", with a large number of professionals from many Ukraine?s leading mining research centers, has developed a research and design work program that includes the following principal stages: 1. Analyzing geomechanical conditions of combined mining of magnetite quartzite and rich ore deposits; determining mechanisms of moving of rock strata underworked by underground mining and places of hazardous area monitoring. 2. Investigating anthropogenic factor influence on the safe state level of rock strata underworked by underground mining (laboratory studies). 3. Developing processing techniques for continuous remote monitoring of rock mass in areas of underground cavity influence. 4. Modeling the state of rock mass based on results of pilot GIS hardware measurements. 5. Developing an expert diagnostics system for rock mass state in areas underground void influence. 6. Experimental investigation and testing the GIS, its improving for efficient application. After testing the pilot GIS it is supposed to be implemented at all mining enterprises as an integral part of iron ore mining and processing technology in the Krivbass area.

Aug 1, 2013

By C. A. Pickles

Nickeliferous limonitic laterite ores contain considerable free moisture. In this research, the application of microwave radiation for the drying of this ore was investigated. The effects of sample mass, initial moisture content and porosity on the microwave drying rate were studied and the results were compared to those obtained with conventional drying. Microwave drying rates of two to three times the conventional values were achieved. Further enhancement of the microwave drying rate was realized by increasing the flow rate of air over the sample or by operating at reduced pressure. The high microwave drying rates were attributed to the inverted temperature gradient which resulted in internal heating and boiling and this in turn promoted movement of the water, both as liquid and vapour, to the surface.

Jan 1, 2005

By M. Wu, G. Plascencia, A. E. M. Warner, A. Vahed, T. A. Utigard

Nickel oxide granules formed by pyrohydrolysis of a chloride solution, were reduced in hydrogen. Below 400 °C, an incubation period was observed, followed by very slow reduction. In the temperature range from 400 to 600 °C, the rate of reduction increased with increasing temperature and increasing hydrogen pressure. Microscopic analysis showed that in this temperature range the reaction followed the shrinking core model. Above 600 °C, the reduction rate decreased noticeably before suddenly becoming very fast at and above 950 °C. Microscopy showed inner bands of metallization inside the outer metallic rim, indicating partial blockage of the interface between the reacted and un-reacted NiO core. At these temperatures, particle agglomeration and sintering were also found to take place. Surface segregation of sulphur may account for the slow down in reduction rate above 600 °C. From an industrial point of view, reduction should be carried out from 550 to 600 °C with as high a concentration of hydrogen as possible. If sintering and agglomeration are not of any concerns, reduction can be carried extremely fast at about 1000 °C.

Jan 1, 2005

By A. W. F. Smith, P. B. Prangnell, D. N. Crowther, P. J. Apps

It is well known that the refinement of grain size in metals leads to a significant improvement in important mechanical properties. As part of a European collaborative project, processing schedules have been investigated aimed at producing a homogeneous ultra-fine ferrite and spheroidised carbide aggregate microstructure structure in high carbon (CMn) steels (0.6-1.2wt%C), via conventional 'warm' rolling and innovative Equal Channel Angular Extrusion (ECAE). Suitable deformation schedules were determined from dilatometry and thermo-mechanical Gleeble simulations. Evidence of an ultra-fine ferrite and carbide aggregate microstructure following 'warm' rolling is given. A significant improvement in tensile strength, particularly proof stress (0.2%) was also noted in comparison to material deformed at higher temperatures. Concurrent Equal Channel Angular Extrusion (ECAE) experiments investigated microstructural evolution with incremental strain. Extensive analysis was carried out using various techniques, including high resolution Electron Back Scattered Diffraction (EBSD). Evidence of ferrite grain refinement was noted in a eutectoid composition steel. A sub-micron ferrite structure was observed following high strains (E-3.33) and the mechanical properties exhibit a marked increase in tensile strength.

Jan 1, 2004

By J. P. Grieco, F. W. Grieco

"Manufacturing of Jaw CrushersOriginIn 1858 Eli Whitney Blake invented the first successful mechanical rock breaker-the Blake-type jaw crusher. Blake adapted a mechanical principal, the powerful toggle linkage system used to transform rotating motion and energy into oscillating mot ion and tremendous compressive forces. Today these same principals apply and the basic Blake-type jaw crusher is one of the leading machines of its class for heavy duty primary crushing service.In 1881 Philetus W. Gates patented a design for a crusher, the forerunner of the modern gyratory crusher which dominated the field from the late 1800s to the early 1900s. In 1910 the largest gyratory crushers built had 48-inch openings. However, about this time the jaw crusher came to life when the Power and Mining Machinery Co. built an even larger sized opening crusher-a giant 84-inch by 60-inch jaw crusher for a trap rock quarry in Pennsylvania. A 24-inch gyratory crusher became the ideal sized secondary machine for this size jaw. From that time on jaw crushers were looked on favourably as primary breakers and lines were brought up to date to parallel the already developed gyratory lines.FunctionMost heavy duty Blake-type jaw crushers work basically the same way. They are ruggedly designed and capable of crushing material in some cases in excess of 80, 000 p.s.i. compressive strength. They are very simple machines with few moving part s and, with the exception of replacement of renewable parts, are relatively maintenance free. It is quite common to have these machines in product ion for 20 to 30 years. The following will de scribe how these machines work. Large-diameter high-inertia flywheels which are connected to the main eccentric shaft, rotate inside a connecting rod type mechanism called a Pitman. It transforms rotating motion into vertical oscillating motion. This vertical motion is in turn transformed into reciprocating mot ion by means of a system of 2 toggles, each connected to the Pitman. The rear toggle is connected to the fixed rear head, and the front toggle is connected to the swing jaw which is hinged at the top of the crusher. With each rotation of the eccentric shaft the swing jaw opens and closes on rock which is fed into the crusher chamber, crushing the rock in a series of bites. These bites, or strokes as the y are called, usually vary between 1/2 inch to 1 1/2 inch at speeds of 120 to 200 strokes per minute. The reduction ratio of feed input to discharge is usually about 8 to I. Output capacities can vary from 100 tons/hour to 1200 tons/hour depending on the size of machine and its discharge opening. Horsepower requirements can vary from 75 hp to 400 hp.The entire crusher chamber is lined with replaceable 14070 manganese steel liner plates. This material is ideally suited for the job since it hardens as it wears during crusher operation. Manganese is also used in the high wear areas at each end of the toggle plates."

Jan 1, 1985