Crusher Operation Research Articles

Intrusion Monitoring Based on High Dimensional Random Matrix by Using Ultra-Weak Fiber Bragg Grating Array

In order to ensure that a perimeter security system can work effectively, a convenient and effective event detection algorithm has an important engineering significance. Given the above background, in this paper, we propose a high reliability intrusion event recognition method and vibration sensing system, based on ultra-weak fiber Bragg grating array, by using high dimensional random matrix. We obtain a high sensitivity optical interference signal by constructing a patch-matched optical interference system, then compose the demodulated interference signal into a high-dimensional random matrix. The statistical characteristics of the matrix for the Marcenko-Pastur (M-P) law and ring law are used to confirm the presence of intrusion events efficiently, which can reflect the limit spectrum distribution of the high-dimensional random matrix; meanwhile, the abnormal state quantity and moment are obtained. Further, the average spectral radius value is used to judge the fault cause. Field experimental results show that the proposed method can effectively obtain the correct monitoring data for the sensor array. By comparing the monitoring results of normal operation and crusher operation, we can detect the intrusion event in 4.5 s, and the accuracy rate can reach more than 90%, which verifies that the proposed high-dimensional random matrix analysis method can work properly, proving a practical engineering application prospect.

Evaluation of workplace exposure to respirable crystalline silica in road construction industries in Alberta.

Occupational exposure to respirable crystalline silica (RCS) is common for several occupations in construction, not only because of its presence in many handling materials but also in processes such as grinding and sawing. This study investigated workplace exposure to RCS as quartz in industries and occupations within road construction in Alberta through the RCS monitoring database provided by the Alberta Roadbuilders and Heavy Construction Association (ARHCA) between 2007 and 2016. Descriptive statistics were calculated for exposure-related variables, and mixed model analysis was performed to determine factors affecting the exposure levels. Results showed that the highest exposed workers were in the sand and gravel industry (GM = 45μg/m3). For worker occupations, geometric means ranged from 78μg/m3 for crusher operators to 10μg/m3 for concrete truck operators. The maximum exposure severity was 33.3 times the occupational exposure limit (OEL) for the sand and gravel and 31 times the OEL for tower operators. The results also showed the effect of seasonal variability on RCS exposure levels. The heterogeneous exposure results indicated significant room for improvement and that controls should focus more on the activity performed than the occupation to lower exposure to RCS levels in industries.

Substantiation of research results on energy efficiency of basalt crushing

Purpose. To experimentally determine the main design and operational parameters of the influence of rock mass properties on the Roller Crusher performance when processing basalt rock mass. Methodology. The crushing and grinding of basalts are studied by the methods of mathematical statistics in order to identify the results obtained and determine the dependences of technological parameters on the mechanical impact factors. Experimental studies are carried out on the example of basalts from the Rafalivskyi quarry in the Rivne region. Findings. It has been revealed that the elemental composition of rocks in the benches of basalt quarries has a different mineral composition. Experimental studies of the rock crushing results have determined the efficiency of using screening for crushing basalts. The experimental dependences of the roller crusher performance in crushing and grinding modes on the properties of the rock mass have been obtained. Originality. The value of crushed rock fractal joints has been found, when using cone and centrifugal crushers, which is characterized by the shape factor and fractal dimension D. For cone crusher Kf=2.15.0 and D=1.4. For centrifugal crusher Kf=1.51.8 and D=1.17. These parameters testify to the energy feasibility of using centrifugal crushers. The high value of the multiple correlation coefficients R2 and Fisher criterion F, whose value at a significance level of 0.05 is higher than the critical one, indicates a sufficient convergence between the experimental and theoretical results and the accuracy of the obtained analytical dependences. Practical value. The generalized models for determining the Roller Crusher performance, obtained for each rock type, based on significant factors, greatly facilitate the choice of parameters for crushing and grinding processes, and also allow choosing a rational mode of crusher operation.

Обоснование параметров и промышленное освоение упругой пальцевой муфты с эластичным элементом дискового типа в приводе четырехвалковой дробилки

Dynamic loads appear in operation of the mechanical equipment leading to parts, assemblies and mechanisms failure reducing the mechanical equipment durability and reliability. Four-roll crushers are widely used in fractional preparation of charge materials in the agglomerate production. Production experience in such machines operation shows that shock loads arising from the material destruction between working surfaces of the rolls are leading to the relatively rapid failure of the crusher drive elements, in particular bearings, gears, gearwheels and couplings unable to completely absorb the dynamic loads. Based on analyzing various couplings, the use of a finger coupling with the elastic disk-type element was justified in the four-roll crusher drive. Such a coupling was able to transmit relatively high torques and to effectively damp significant shock loads that occur during the crusher operation. The method of planning the central composite rotatable uniform of the second order and the finite element method for calculating stresses using a computer-aided design system formed the basis and proposed an analytical expression to determine the torque depending on the hole diameter center for the fingers and the width of an elastic element with certain physical and mechanical properties, as well as the formula for calculating the total width of the disc-type elastic element from the required torque and the diameter of the hole centers for fingers. Values of the design and technological parameters of the finger coupling with the disc-type elastic element were obtained for the process of crushing solid fuel in the DChG 900?700 crusher under conditions of the sintering shop of the Branch No. 1 AMK of YuGMK LLC. Tests and implementation of this type of coupling in industrial conditions were carried out.

Determining the rational operating parameters for granite crushing to obtain cubiform crushed stone

Purpose. Determining the rational operating parameters for granite crushing under impact in the field of centrifugal forces to obtain cubiform crushed stone. In order to achieve the purpose set, the task is to determine the operating parameters for obtaining the main grain-size classes: -50.0 + 20.0; -40.0 + 20.0; -20.0 + 10.0; -10.0 + 5.0 and 5.0 mm. Methods. The crushing process of granite crushed stone is studied in the conditions of the Kolomoievskyi Granite Quarry, Dnipropetrovsk region. Granite crushed stone with an initial grain-size of 100.0-0.0 mm and strength grade of M1400 is subjected to crushing. The accelerating rotor rotation frequency is the design value n = 200-1200 min-1. Fine crushing of granite is performed in a centrifugal-impact crusher by a free impact in the field of centrifugal forces. Findings. The optimal speed modes of centrifugal crusher operation, which provide the production of high-quality crushed stone with a maximum content of 90-95% cubiform fractions, have been substantiated. Originality. The yield dependences have been obtained of the grain-size classes: -50.0 + 20.0; -40.0 + 20.0; -20.0 + 10.0; -10.0 + 5.0 and 5.0 mm depending on the speed mode of the centrifugal crusher operation. Practical implications. The operating parameters for obtaining the main grain-size classes of cubiform crushed stone from granite have been determined: -50.0 + 20.0; -40.0 + 20.0; -20.0 + 10.0; -10.0 + 5.0 and 5.0 mm. In particular, it has been determined that for the production of cubiform crushed stone with -50.0 + 20.0 mm grain-size, the rotor rotation reasonable speed is 400-500 min-1 (the speed of material departure from the accelerating rotor is 45-50 m/sec); for cubiform crushed stone of -40.0 + 20.0 mm grain-size, the speed mode is 200 min-1 (25 m/sec); for cubiform crushed stone of -20.0 + 10.0 mm grain-size – 600-650 min-1 (70-80 m/sec), respectively. The maximum content of cubiform fractions in the -20.0 + 10.0 mm grain-size class is 95%, which is achieved at a rotor speed of 650-700 min-1 (departure speed is 75-80 m/sec). The maximum content of cubiform fractions in the -10.0 mm grain-size class is 94-95%, which is achieved at the accelerating rotor speed within 700-800 min-1 (departure speed is 70-80 m/sec). The obtained data make it possible to practically choose a rational speed mode of the centri-fugal-impact crusher operation to obtain the maximum yield of cubiform crushed stone.

Optimization of Aggregate Production Circuit through Modeling of Crusher Operation

The paper concerns investigation of the effect of impact crusher operation on selected qualitative characteristics of mineral aggregate products. Qualitative characteristics of crushing products in terms of size reduction ratio and fine particles contents were analyzed from the point of view of operational parameters of the impact crusher. An investigative program was carried out on a plant scale and two primary parameters of the impactor were analyzed: velocity of the crusher rotor and the width of the outlet gap. The models of the crushing device operation were built separately for each type of the tested material, as well as for general conditions.

Investigation of the jaw crusher operation with backlash eliminators

The condition for the appearance of additional dynamic forces in the presence of gaps in the journal bearings of the jaw crusher is determined. The design of the backlash eliminator equipped with pneumatics is described. It was experimentally established that the use of pneumatic devices for backlash elimination in the interfaces of the moving links, using journal bearings, during the operation of the jaw crusher, reduce the magnitude of accelerations and, therefore, increase the reliability of the crusher as a whole.

Crushing and screening digital system

The article proposes the structure of the Crushing and Screening Digital System (CSDS). A software implementation of a digital system for a cone crusher has been completed, which allows integrating a set of interfaced technological units in the control of one hardware equipment as part of the controller and installed at the operator station of the SCADA system. The most important functions of the CSDS are the continuous monitoring of the equipment condition of the complex of crusher mechanisms and aggregates in the process of work and the formation of a signal to regulate the productivity of the crusher. CSDS allows you to integrate in the control of one hardware as part of the selected controller and the SCADA-system server crusher installed at the operator station, a set of interfaced technological units, the efficiency of joint work of which is largely determined by the degree of coordination and the speed of two-way information exchange. In the event of malfunctions or abnormal situations, it will notify the operator. All accidents and crusher operation parameters are recorded in an electronic archive. The developed system provided a significant increase in the operator’s comfort, providing him with a single user interface for controlling the cone crusher from one operator station and an additional amount of information and services.

Studying the operational efficiency of the centrifugal-impact feed grain crusher of the new design

Crushing feed grain involves hammer crushers, which are characterized by high specific energy consumption and its uneven fractional composition. It is possible to obtain high-quality shredded grain with less energy when using a centrifugal-impact crusher of the new design with a hole in the loading neck to supply the chopping chamber with additional air at a rate of up to 4.8 m/s. An additional hole provides a 1.8...13-time increase in the airspeed through the unloading neck when the rotor’s rotation frequency changes from 3,750 to 2,250 min –1 , thereby enabling the timely evacuation of the shredded material from the crusher. The regression equations have been derived to determine the structural and regime parameters of the shredder, which ensure the maximal performance and minimal unit energy costs. The greatest impact on crusher productivity is exerted by the diameter of the sieve holes and the area of the bunker’s unloading window. The greatest effect on the specific energy intensity of the grinding process is exerted by the diameter of the sieve holes. The maximal performance of the crusher, 1,440 kg/h, and the minimal energy capacity, taking into consideration the achieved grinding degree, of 2.1 W∙s/(kg∙grinding degree unit), are observed when using a sieve with the holes’ diameter of 7 mm, the rotor’s rotation frequency of 3,500 min –1 , and the maximally open unloading window of the bunker, at F=1.458 m 2 ·10 –3 . The specific energy consumption for chopping barley is less by 1.22...1.89 times than that of the hammer crushers RVO 35, DB-5, KD-2A. The dust-like fraction is less than 5.74 %, which is half the amount of the hammer crusher DM-6. The rational crusher operation modes have been determined in order to prepare feed grain for feeding farm animals of different species and ages

Investigation and analysis of occupational hazards and control measures in waste incineration power generation enterprises

Objective: To investigate occupational hazards in waste incineration power generation enterprises. Methods: From May 2016 to September 2018, four garbage incineration power generation enterprises in different regions and scales were selected as the survey objects. Investigated and analyzed the types of occupational hazards, workplace distribution and occupational disease prevention facilities and the concentration (intensity) of major types of work and workplace occupational hazards were also improved Line detection and analysis. Results: Silica dust could be seen in slag tank, slag sorting and crusher operation position. The concentration of silica dust in each workplace fluctuates within 0.3-1.1 mg/m(3). Both the concentration of silica dust in the workplace and the time weighted average allowable concentration (C-TWA) of dust exposure of dust exposed workers were detected, but none of them exceeds the requirements of the national occupational exposure limit. Carbon monoxide, ammonia, nitrogen dioxide, hydrogen sulfide, non methane total hydrocarbon, formaldehyde, hydrogen fluoride, hydrogen cyanide, hydrochloric acid, sodium hydroxide and ozone were detected, but all meet the requirements of national occupational exposure limit. The 8-hour equivalent a sound level (L(ex·8h)) over 85 dB (A) mainly includes boiler, steam turbine, electrical inspector and auxiliary value of water treatment. Conclusion: The occupational hazards of waste incineration power generation enterprises are serious. Occupational health management and occupational health monitoring to reduce their occupational hazards to workers.

Prevalence of Occupational noise induced hearing loss (ONIHL) among industrial workers in Bhutan.

Introduction: Exposure to any type of noise has a potential risk. Higher the level of noise and longer duration of exposure, the more the risk for the hearing sensitivity and health as a whole. The objective of the study is to determine the prevalence of Occupational Noise Induced Hearing Loss (ONIHL) among the industrial workers in Bhutan and to ascertain high risk establishment and vulnerable occupations. Methods: The hearing assessment was conducted among 1638 workers considering different types of industries and occupations to ascertain the prevalence of occupational noise induced hearing loss and vulnerable group amongdifferent industries and occupations. Descriptive statistics and binary logistic regression were performed to test the significance of ONIHL among the various independent variables. Results: The study found that the prevalence of ONIHL stands at 27.9% among industrial workers in Bhutan. 42.45% of candidates who had ONIHL reported with tinnitus in either or both ears. This study founda significant association between the exposure duration and the severity of ONIHL among the industrial workers. Considering the type of industry, wood based industry, hydro services, cement and polymer were found to have a higher prevalence of ONIHL and similarly, higher prevalence of ONIHL were found among occupations such as blaster, chipper, carpenters, dryer (knife grinder) and crusher operators. Conclusions: This study conduces that prevalence of ONIHL among industrial workers is found to be at the higher side and some of the occupations and industries impose higher risk. The study suggests that there is need for intervention such as strict enforcement of the permissible exposure limit, monitor and evaluate hearing conservation programs, and providing advice and recommendation to address such issues by the relevant agencies and industries

Influence of jaw crusher parameters on the quality of primary crushed aggregates

A parameter study using a jaw crusher is designed to investigate the influence of feed gradation, feed rate, crusher setting and crusher speed on the crusher operation and the quality of the produced aggregates. The study is focused on the production of all-in large-size (top size ⩾90 mm) aggregates, suitable for use in subbase and frost protection layers in a pavement structure. Aggregate quality is measured in terms of product gradation, particle shape and mechanical properties.Feed gradation, crusher setting and crusher speed affects the specific energy consumption during crushing. Particle shape is affected by all parameters; feed gradation, feed rate, crusher setting and crusher speed. Mechanical properties are least affected by the jaw crusher parameters, but sample preparation using laboratory crushing clearly affect mechanical properties.The results from this study provide valuable knowledge for the optimisation of single-stage crushing regarding crusher operation and aggregate quality. By adapting the crushing process to the available feed material and desired product, the quality of the crushed product can be optimised along with the crusher operation.

Occupational risk assessment in crusher operators in polymetals production

A comprehensive study of working conditions and health status of individuals running the crusher machines was done. Occupational risk assessment was conducted. The impact of the production process on the body systems functioning was estimated.

Diagnosis of the rock crushing modes to increase the efficiency of one-roll crusher operation

In the paper the hypotheses of destruction of brittle materials are given, as well as the analysis of energy costs for crushing. The methods of crushing are considered and a comparative analysis of their energy capacity and quality of the product is carried out. The parameters of the crushing process are determined from the point of view of their productivity and, accordingly, their energy efficiency. It is shown that the process of crushing in the one-roll crushers is due to the frictional forces acting between the surfaces of the roll and a piece of the crushed material, and also between the piece and the immovable jaw.The comparison of initial sizes of the crushed pieces in the crushes with the vertical and inclined surfaces of immovable jaw, which shows that with the increase in the bend angle of the immovable jaw the degree of crushing increases. Based on the analysis of forces acting on the crushed material in the one-roll crusher with the inclined surface of the jaw, the calculation of maximal possible value of the bend angle of the immovable jaw is performed.

Mathematical modeling of a vertical shaft impact crusher using the Whiten model

Vertical Shaft Impact (VSI) crushers have been used as interesting alternatives to cone crushers, particularly in the production of aggregates for the construction industry, not only due to their good energy efficiency but also to their ability to generate more isometric and tougher particles, which is highly desirable in cement mortars and concrete applications. Several mathematical models for the VSI crusher have been proposed in the last two decades or so. The Whiten crusher model, originally developed for cone crushers, has served as the basis of several approaches to model VSI crushers. In the present work, the Andersen/Awachie/Whiten model has been used as the basis for modeling a VSI crusher operating in an industrial plant in Brazil, processing quarry rock to product manufactured sand. Nineteen industrial experiments, covering a range of feed rates, rotor speeds, feed distributor types and feed size distributions, have been carried out. The approach demonstrated to be capable of providing satisfactory estimates of the VSI performance, being able to predict the product size distribution and the specific energy consumption with confidence over a wide range of operating conditions. Since it uses a model that is already available in commercial plant simulators, it may be used, with additional expressions, in simulating any desired circuit. Model parameters such as K3 and T10 were found to be particularly influenced by key operational variables such as feed rate and rotor frequency. The significant effect of feed rate on the performance of the VSI crusher studied has been discussed on the basis of simulations of the material flow pattern inside its feed distributing system, simulated using the discrete element method. According to these simulations, it has been inferred that change in the behavior of VSI from lower to higher feed rates may be related to the transition from material being fed predominantly to the rotor, to the increasing contribution of the cascading effect.

Analysis of cone crusher performance with changes in material properties and operating conditions using DEM

Discrete Element Method (DEM) simulation with non-round particles and including breakage has been used to understand the breakage behaviour and operating performance of an industrial scale cone crusher using a representative ore. The breakage model uses a replacement strategy and impact energy specific progeny size data from a Drop Weight Test (DWT). There is a strong variation in the breakage behaviour with height in the compression region as the differing profiles of the concave and mantle create five different regions with monotonically decreasing width and differing degrees of convergence between the surfaces. These control the rate of motion and the ability to load and break the particles, and determine whether high forces are generated via multi-particle stress chains or as single particle loading directly from the liner surfaces. The larger feed particles jam in the compression zone prior to breakage and cause observable obstruction to the flow of finer material and strong non-uniformity in the flow of product down the lower part of the mantle. Trends in the coarseness of product and changes in steady state throughput are identified with changes in material properties (rock breakage energy and friction coefficient) and crusher operating parameters (Closed Side Setting and crusher rotation rate).

Underestimation of respirable crystalline silica (RCS) compliance status among the granite crusher operators in Malaysian quarries

The aim of this study is to determine exposure levels as well as compliance status on respirable dust and respirable crystalline silica (RCS)-quartz exposure among crusher operators at Malaysian quarries. The exposure level at each crushing process was compared. Monitoring was performed among 70 crusher operators at nine quarries. Eight hours long-term personal samples were collected according to the National Institute of Occupational Safety and Health (NIOSH) Manual Analytical Method (NMAM) 0600 for respirable dust and NMAM 7500 for respirable crystalline silica (RCS-quartz). A questionnaire on silica dust monitoring and control was also sent to all granite quarries in Malaysia. The results indicated that the mean percentage of RCS-quartz in silica dust was 23.7 %. The mean value for crusher operators’ exposure was 0.426 mg m−3 for respirable dust and 0.091 mg m−3 for RCS-quartz. Around 30.5 % of crusher operators were exposed to RCS-quartz levels above the permissible exposure limit (PEL) based on Malaysian’s Occupational Safety and Health Regulations 2000. Operators in charge of combined secondary and tertiary crusher plants were exposed to 0.116 mg m−3 of RCS-quartz, which was higher compared to those operating individual plants. Results on posted questionnaire indicate that Malaysian quarries are more preferred to perform respirable dust monitoring (37 %) instead of specific RCS-quartz monitoring (22.6 %). Low exposure to respirable dust may conceal the need to justify comprehensive crystalline silica dust monitoring and lead to underestimation of RCS-quartz exposure. A high percentage of non-compliance exposure on personal RCS-quartz exposure should establish the need for quarry management to focus on better implementation of dust control systems.

Vibration induced white-feet: Overview and field study of vibration exposure and reported symptoms in workers

Workers who stand on platforms or equipment that vibrate are exposed to foot-transmitted vibration (FTV). Exposure to FTV can lead to vibration white feet/toes resulting in blanching of the toes, and tingling and numbness in the feet and toes. The objectives are 1) to review the current state of knowledge of the health risks associated with foot-transmitted vibration (FTV), and 2) to identify the characteristics of FTV and discuss the associated risk of vibration-induced injury. Workers who operated locomotives (n=3), bolting platforms (n=10), jumbo drills (n=7), raise drilling platforms (n=4), and crushers (n=3), participated. A tri-axial accelerometer was used to measure FTV in accordance with ISO 2631-1 guidelines. Frequency-weighted root-mean-square acceleration and the dominant frequency are reported. Participants were also asked to report pain/ache/discomfort in the hands and/or feet. Reports of pain/discomfort/ache were highest in raise platform workers and jumbo drill operators who were exposed to FTV in the 40 Hz and 28 Hz range respectively. Reports of discomfort/ache/pain were lowest in the locomotive and crusher operators who were exposed to FTV below 10 Hz. These findings are consistent with animal studies that have shown vascular and neural damage in exposed appendages occurs at frequencies above 40 Hz. Operators exposed to FTV at 40 Hz appear to be at greater risk of experiencing vibration induced injury. Future research is required to document the characteristics of FTV and epidemiological evidence is required to link exposure with injury.

Dynamic Behaviour of a Vibrating Jaw Crusher for Disintegration of Hard Materials

Abstract One of the trends in design solutions of crushers ensuring the crushing ratio of about 30 involves the application of the vibratory-impulse action to the material to be crushed. Crushers utilising these effects are referred to as vibratory crushers. During the vibratory crushing the material to be disintegrated is subjected to the action of fast changing shearing forces, which leads to the material being crushed either by applied impulses or by fatigue action, unlike conventional crushers where the structure of the material is damaged by the applied pressure. A dynamic analysis of the vibrating jaw crusher operation is provided and its potential application to crushing hard materials, such as alloy materials containing iron and slag from metallurgical processes are explored.

The assessment of particulate matter emitted from stone-crushing industry by correlating rock textures with particles generated after comminution and dispersed in air environment

The generation and emission of particulate matter from abrasion industry are subjects of the pollution monitoring by multidisciplinary study involving earth sciences and engineering disciplines. This work investigates the correlation between textural properties of in situ rock with class size distribution and morphology of particles generated after rock comminution and particles emitted in the air. A special comminution-dust sampling architecture was realised. The combined use of scanning electron microscopy and particle size analyser was considered in performing digital image analysis on both crushed products and airborne particles collected onto membrane filters. The results show that the size and morphology of crushed particles are linked to the petrographic rock properties. In particular, particles with fibrous morphology are prominent in rocks showing foliated textures where elongated minerals occurred, with implication for asbestos-bearing rocks. For what concerns the airborne particles, the results show that their aerodynamic diameters are independent of the crusher operating conditions. External parameters probably intervene in the distribution of the airborne particles emission, including the dynamic air fluxes, or environmental conditions. By applying mathematical models, the morphology and size range of airborne particles following the comminution processes can be predicted, and results has implication for pollutants contamination due to particulate matters emitted by crush stone industry.