Jaw Crusher Research Articles

Effects of Crushing and Grinding on the Porosity of Hardened Cement Paste

The objective of this paper was to study the impact of crushing and grinding on the porosity of hardened cement paste, which is responsible for the high values of recycled concrete aggregate (RCA) water absorption. Hardened cement pastes with three different water to cement ratios have been crushed in one to three steps with a jaw crusher to produce aggregate larger than 2 mm and ground with a disc crusher in order to produce particles lower than 150 µm. Water absorption tests and mercury intrusion porosimetry (MIP) were performed for the different resulting sizes. It was observed that the crushing procedure did not significantly affect the porosity of the aggregate. However, MIP performed on the powders showed differences in the pore size distribution compared with the monolith. This can better be attributed to a modification of the surface roughness of the particles than to a modification of their porosity. In all cases, the water absorption rate was the highest during the first 1 min after soaking in water. It was also observed that the morphology of the particles changed from a step of crushing to another.

Effect of Crushing Method on the Properties of Produced Recycled Concrete Aggregates

Construction and Demolition Waste (C&DW) is generated around the world and its quantity will increase in the future. Recycling has become the favored method of dealing with concrete waste but, to avoid its downcycling, it is important to develop a recycling process which is able to produce high-grade recycled concrete aggregates (RCA). To that end, studying the influence of the production process on the properties of RCA can prove to be a crucial step toward a more circular construction industry. In this study, the influence of the crushing method is investigated. Samples of five laboratory-made concretes have been crushed using the most common mechanical crushing methods (impact crusher and jaw crusher), and the particle size distribution, morphology, hardened cement paste content and water absorption of the produced RCA have been measured and analyzed. The findings indicate that the use of impact crushers results in the production of RCA possessing more spherical geometric characteristics, albeit with a broader particle size distribution and a relatively higher content of fine particles as compared to those obtained from jaw crushers. Additionally, it is observed that the employed crushing technique seemingly exerts no discernible impact on the hardened cement paste content and the water absorption in the context of the studied concretes.

Estimation of Energy Consumption for Concentrate Process of Tungsten Ore towards the Integration of Renewable Energy Sources in Mongolia

It is important to estimate the energy required in ore processing to select the most affordable and efficient energy system for the integration of renewable resources into the mining industry. In the present work, the energy consumption for the concentrate of tungsten ore in Mongolia was theoretically predicted based on operational variations (particle size and the hardness of the tungsten ore) and different equipment. The energy was in the range from 0.48 to 1.32 kWh/t for the crushing stage, and a cone crusher was more suitable than a jaw crusher due to the particle size of feed material and product. The required energy in the grinding stage was from 6.22 to 11.88 kWh/t using a SAG mill or from 3.04 to 7.39 kWh/t using a ball mill. The further separation by a flotation consumed 4.83 kWh/t or by a shaking table consumed 1.29 kWh/t. The maximum energy consumption per hour for the whole process was estimated to be 2–3 MW, which was better to integrate with a hybrid renewable energy system. The sizing method Power Pinch Analysis was used to estimate the electric supply based on the combination of wind, biomass and solar resources, which was sufficient for the demand from the predicted range of energy.

FEATURES OF VIBRATION CRUSHING OF GEOLOGICAL SAMPLES OF MATERIAL

An innovative method of vibro-impact grinding of geological samples, implemented in a vibrating jaw crusher with an inclined crushing chamber, is considered to obtain a product of -1 mm in one crushing cycle. The technique consisted in comparing the results of crushing quartzite and magnetite with a particle size of 60...80 mm according to the existing multi-stage technology using jaw and roller crushers, as well as the proposed single-stage technology using a vibrating jaw crusher. Three technological schemes for the preparation of samples of quartzite and magnetite were modelled with obtaining granulometric characteristics after each piece of equipment. The analysis of the results showed almost the same particle size distribution of the samples according to the multi-stage scheme: jaw crusher, screening -2mm, roller crusher, screening -1mm and single-stage: vibrating jaw crusher, screening -1mm. The output of the finished material was 80%. The studies substantiated the feasibility of creating a small-sized vibrating jaw crusher with a crushing ratio of i ≥ 100 for the preparation of geological samples, operating in an open cycle and replacing at least two pieces of crushing equipment, two screens and mounting elements, which significantly reduces the metal consumption of the structure, the occupied area and simplifies maintenance.

Sustainable development of recycled concrete aggregate through optimized acid-mechanical treatment: A simplified approach

Present research develops an optimized acid-mechanical treatment for recycled concrete aggregate (RCA). RCA prepared in the laboratory jaw crusher is further soaked for 24 h in a mild acetic acid solution. Acid-soaked recycled aggregates (SR) are mechanically treated at a series of charges and drum revolutions using Los Angeles machines. A performance-based quality identification approach is used to compare acid-mechanically treated recycled concrete aggregates (SRij). The VIKOR indices (QI) for each SRij is calculated by applying a multi-criteria decision-making approach. Based on performance, three SRij with the lowest QI are selected for an experimental study. The present research achieves 71.27 MPa compressive strength for concrete composed of a SRij with the lowest QI. This strength is around 16.06% higher than concrete composed of parent aggregate. Flexural strength, split tensile strength, fracture energy, ultrasonic pulse velocity (UPV) values, rapid-chloride penetration test (RCPT) values, water absorption, and abrasion resistance are in the range of what is expected for parent aggregate concrete. The scanning electron microscope (SEM) image analysis shows that the well compacted and uniform surface morphology of aggregate strengthens the newly developed interfacial transition zone (NITZ) and old interfacial transition zone (OITZ). Acid treatment reduces microcrack lengths and widths and mechanical treatment reduces microcracks and pores by reducing adherent mortar optimally. X-ray diffraction (XRD) analysis shows the lower calcium hydroxide (CH) content in the mortar attached to the SR. A reduced CH content lowers the porosity in the adhered mortar. Thus, improved quality of attached mortar and its reduced porosity strengthen the old interfacial transition zone (OITZ) and lowers the sorptivity of the concrete than reported and almost equal to that of parent aggregate concrete.

RESEARCH OF PARAMETERS AND MODES OF THE VIBRATION CRUSHER

One of the main directions of research on machines for the production of building ma-terials is the reduction of energy consumption. Solving the problem related to the determination of energy consumption is a rather difficult task, since energy consumption depends on a number of factors that change during the operation of the machine and are difficult to accurately describe. One of the areas of development of machines for the production of construction materials is the creation of resonant vibration machines. Based on the analysis of the latest researches, the prospects of vibrating jaw crushers have been established. The correct selection of parameters that will ensure the operation of the crusher in a stable resonance mode will make it possible to reduce energy costs for crushing. For this purpose, the study of the dynamic parameters of the vibrating jaw crusher is presented in the paper. The efficiency of the double-acting vibratory crusher under study is ensured in the resonance mode with the synchronous adjustment of the movement of the first and third masses and the counterphase movement of the second mass. For this, the stiffness of the elastic connections c1 and c2 is calculated from the condition of resonance of the reduced masses m23 and m12, respectively, and the stiffness of the support springs from the condition of vibration isolation. The physical model of the crusher is presented and the equations of motion of oscillating masses with and without material in the crushing chamber are given. Graphs of the effect on the amplitude of the stiffness adjustment coeffi-cient by frequency were obtained. Based on the equations of motion, the amplitude-frequency characteristics for the corresponding natural angular frequencies (resonance frequencies) are constructed. The mass of the oscillating parts of the crusher has a great influence on the amplitude of oscillations. Rationally selected ratios of oscillating masses provide the required operating mode (in-phase, anti-phase) and provide the re-quired amplitudes of oscillations of these masses. For the given input conditions, the rational limits of the ratios of the oscillating masses are determined to ensure the corresponding frequency regimes. Based on the analysis of the amplitude-frequency characteristics, graphs of the amplitudes of the movement of the oscillating masses of the crusher were constructed. Recommendations for choosing effective frequency modes are given.

Experimental investigation on compressive strength addition of leftover building debris to paver blocks using coir fibre

India is a country under development. Similar to India, other emerging nations also benefit from cost-effective construction methods and affordable building materials for their national development. The building industry generates close to 12 to 14 million tonnes of waste annually, of which roughly 7 to 8 million tonnes are brick and concrete debris. Waste construction material can play a significant role when added to paver blocks. When employed in paver blocks, the waste recycled construction material is cost-effective and long-lasting because of some of its unique features that are applicable to conventional construction materials. After being crushed using a laboratory jaw crusher, this concrete debris can be substituted in two steps for coarse aggregates. In accordance with Indian Standard standards for paver blocks, as a full 100% replacement and a 40% partial replacement. This garbage is either discarded or diverted toward a landfill. The idea of adding concrete scraps to the concrete used to make the interlocking paver blocks with coir fibre is depicted in this study. In comparison to 0.1% and 0.5% coir fibre, the average compressive strength of paving blocks with 0.3% coir fibre produces the best results. Compressive strength, workability, bulk density, specific gravity, flexural strength, splitting tensile strength, and water absorption tests were analysed in order to build paver blocks with coir fire in various percentages by adding leftover construction materials.

Investigation of pozzolanic activity of recycled concrete powder: Effect of cement fineness, grain size distribution and water/cement ratio

In this study, the effect of fineness and grain size distribution of the cement used in the source concrete from which the recycled materials were obtained and its water/cement ratio on the pozzolanic activity of recycled mortar powder were investigated. The specimens, whose strength values were determined, were first ground to a small size with the help of a jaw crusher and then ground into powder in a ball mill. The usability of the powder material passing through the 0.075 mm sieve as a binder was investigated. It was determined that the pozzolanic activity index of the recycled powders varied between 54% and 84%.

Grain size and shape fractal characteristics of gangue in the process of 'jaw breaking-ball milling'.

This study investigates the fractal characteristics of the particle size and shape distribution of gangue powder in the "jaw crushing-ball milling" process using mudstone gangue. For this, fractal theory, laser particle size analyzer, scanning electron microscope and other mesoscopic research methods were introduced. This study has several main factors, including the discharge port width in the jaw crushing stage, the grinding particle size, ball-to-powder ratio in the ball milling stage, and the fractal dimension changes of the gangue in different crushing stages. The results indicate that in the process of "jaw crushing-ball milling", gangue's particle size and shape fractal dimension values changed periodically. During the jaw crushing stage, the particle size fractal dimension increases with the width of the discharge opening, ranging from 1.85 to 1.92. The value of the shape fractal dimension varies from 2.65 to 2.84. Ball milling causes the fractal dimension value of gangue particle size to increase with time before agglomeration and decrease after agglomeration. By comparing different in-grinding particle sizes and ball-to-powder ratio, it is found that the fractal dimension value of gangue particle size decreases with the increase of in-grinding particle size and increases with the increase of ball-to-powder ratio. The final gangue's particle size fractal dimension value is concentrated between 2.5 and 2.8. The fractal dimension of particle shape increases with the increase of the grinding particle size, and decreases with the increase of ball-to-powder ratio. A ball-to-powder ratio greater than 6 gradually reduces its influence on fractal dimensions, and the final shape dimension lies between 1.06 and 1.16. In addition, the increase/decrease range of particle size and shape fractal dimension decreases with the increase of ball milling time, which is also consistent with the grinding kinetics theory. As a result of the changes in particle size and shape fractal dimensions, parameters such as jaw crusher discharge port width, grinding particle size, and ball-to-powder ratio are calculated to provide a theoretical basis for the entire crushing process in the "jaw crusher-ball milling" crushing process.

Flotation of copper smelter slags intensified by impact crushing

This paper examines the mineral and chemical composition of converter slags generated by Balkhash Copper Smelter, as well as the forms in which copper ispresent in them. The paper describes the results of flotation of the above product, which was prior subjected to fine crushing in jaw and hammer crushers. The paper features a comparative analysis that looks at the size distribution and the distribution of the key valuable components by grain size of the slag pre-crushed in jaw and hammer crushers. It is shown that the different breaking techniques realized by these crushers influence the size distribution of the crushed product, the share of particles smaller than 0.071 mm and the distribution of copper by fraction. The authors looked at the grinding kinetics of the copper smelter slags pre-crushed in the above specified crushers and compared the share of –0.071 mm particles, as well as that of –0.045 mm particles (which are the finest fraction). It was established that the optimum hammer crushing duration is 45 min. A longer duration leads to overgrinding. At the same time for the jaw crusher, the overgrinding effect and the accumulation of the –0.045 mm particles become expressed if the crushing cycle lasts for 60 min. Flotation of the pre-crushed converter slags resulted in a quality concentrate containing 27.5 to 39.0 wt % copper (depending on the slag crushing duration). In all cases, the recovery of copper was every time higher (by 5% on average) for slags pre-crushed in the hammer crusher. It is pointed out that impact crushing of copper smelter slags significantly intensifies the flotation process. This should be taken into consideration when optimizing the processing schemes.This research was funded by the Russian Science Foundation; Agreement No. 22-27-00526.

Influence of Basalt Aggregate Crushing Technology on Its Geometrical Properties-Preliminary Studies.

The use of mineral aggregates is related to the increasing demand in construction, railway and road infrastructures. However, mineral aggregates can appear to be of variable quality, directly affecting their suitability for respective earthwork applications. Since the production of mineral aggregates should ensure the standardized, high-quality requirements of the final product, rock-crushing mechanisms should be investigated in a detailed manner. In this context, the aim of the present study is to evaluate and analyze the geometric parameters of basalt aggregates as a result of several rock comminution processes. Basalt aggregates from two deposits in Poland were used in the study. The samples are differentiated regarding both lithological variances, mineral composition as well as the host rock's tuff content. The rock comminution processes were conducted using two types of crushers, namely the laboratory-scale jaw and cone crushers. The feed for crushing was designed based on the original geometric grain composition and the separated feed in the form of flaky and non-flaky particles. The crushability test results demonstrated that the interparticle compression in the jaw crusher resulted in finer products compared to the one in the cone crusher. It was also observed that the flakiness and shape indexes decreased after crushing, both in the feed with the original geometric composition of the grains and those with flaky and non-flaky particles. Nevertheless, a higher flakiness index was obtained after the crushing of non-flaky particles and a lower one after the crushing of flaky particles. The flakiness index for grains below 16 mm after the crushing process was less than 10%, which indicates a more favorable result compared to the original feed. In addition, it was shown that flaky and non-cubical particles were accumulated in the finest (below 8 mm) and coarsest (above 20 mm) fractions in jaw and cone crushing processes, receiving flakiness and shape indexes ranging up to 80-100%. Finally, it was also observed that the lithological variances of the feed material have a significant impact on the particle size distribution of the product. More profoundly, basalt aggregates with a higher tuff content and weathering degree have a higher degree of crushing. The present study, in this context, provides accurate and satisfying information on understanding the crushing mechanisms of two important crushing equipment as well as their rock-crusher interactions.

Features of material movement in a vertical chamber of a vibratory jaw crusher when producing a fine-grained product

Currently, vibrating jaw crushers show a fairly high efficiency of the technological process. An extensive amount of research carried out at the Dnipro University of Technology made it possible for the first time to substantiate the possibility of using a vibratory jaw crusher with a vertically located chamber and a pendulum suspension of the jaws as an independent grinding unit for the production of powder materials. The high-frequency impact nature of the load on the material implemented in vibrating jaw crushers made it possible to reduce the energy consumption and metal consumption of the plant, to increase the degree of crushing, which can reach the value i > 100. However, the specifics of the process of interaction of the material with the surface of the jaws in the vertical working chamber and the features of its unloading remain unknown. The refinement of this process was carried out by an experimental method on a laboratory sample of a vibratory jaw crusher ВЩД-130 using high-speed photography. The crusher includes the main elements: a body mounted on elastic elements, crushing jaws, articulated with the body by means of axes. The side surfaces of the crushing chamber are limited by transparent glass walls rigidly connected to the crusher body. The vertical movement of the jaws was determined by the readings of the vernier. The starting material was pieces larger than 40 mm and large bulk material with a grain size of 10…15 mm. An analysis of the nature of the movement of material throughout the crushing chamber showed the need to consider the chamber of a vibratory jaw crusher as two interconnected zones: crushing and grinding. Further studies were carried out for each zone.The productivity of the crushing zone is determined by a known method. It is necessary to create a rational profile of the working surface of the jaws on the basis of additional studies. Studies of the grinding zone made it possible to obtain a physical picture of the interaction of the material with the jaws over the period. In the lowest position, at the initial moment of unloading, the speed of the finished product is practically zero. When determining the productivity of the grinding zone, it is advisable not to take into account the unloading of the material at the initial speed.

Dynamics Analysis and Chaos Identification of Compound Pendulum Jaw Crusher with Joint Clearance

A dynamic model of the working mechanism of a compound pendulum jaw crusher with clearance is established by the Lagrange multiplier method (LMD) based on the L-N contact force model and modified Coulomb friction force model. The correctness of the dynamic model is verified by MATLAB and Adams comparison simulation, and the best selection range of driving speed and clearance size is determined according to the laminating crushing theory (LCT). The effects of driving speed and clearance size on the shock and chaos phenomenon in the clearance mechanism are analyzed, as well as the vibration force applied to the foundation. The results show that, under the premise of meeting the requirements of crusher production capacity, increasing the driving speed and reducing the clearance size can weaken the shock and chaos phenomenon during the operation of the mechanism, improve the dynamic performance and enhance the operation stability, and the service life of foundation is prolonged with the stability of vibration force. Furthermore, the optimal combination of driving speed and clearance size is determined, which provides a theoretical basis for the optimization of the vibration force of the jaw crusher.

Evaluating the performance of an industrial-scale high pressure grinding rolls (HPGR)-tower mill comminution circuit

This paper presents the commercial implementation of a novel comminution circuit with high pressure grinding rolls (HPGR) followed by tower mill in a copper–lead–zinc ore dressing plant. With a throughput of 650 t/d, the comminution circuit comprises three stages of crushing by a jaw crusher, cone crusher, and HPGR as primary, secondary, and tertiary crushers and one stage of grinding by tower mill. Closed with a flip-flow screen, the HPGR reduces the feed size from −12 to −1 mm, and the tower mill circuit produces a flotation feed with a fineness of 85 % passing 0.074 mm. This comminution circuit has HPGR for partial coarse grinding and uses tower mill to replace the energy-inefficient ball mill for primary grinding. The circuit has been operated for more than 7000 h without the replacement of rolls and is projected to reach its design service life of over 13,000 h. Compared with a conventional dressing plant handling similar ores using an SABC circuit, 20.16 % energy savings and improved separation are realised. Opportunities and considerations for this novel comminution configuration are discussed.

Effect of recycled concrete aggregate with different degrees of initial alkali–aggregate reaction damage on the mechanical behavior and porosity of self-compacting recycled aggregate concrete

The use of recycled concrete aggregate (RCA) is an effective approach to achieve environmental sustainability. However, the presence of defects due to previous alkali–aggregate reactions (AARs) has caused reluctance toward its use in constructions. This study investigated the application and influence of RCAs with different degrees of initial AAR damage on the mechanical behavior and porosity of self-compacting recycled aggregate concrete (SCRAC). Concrete cubic specimens with different degrees of AAR were produced by soaking the raw materials in a high-alkaline solution. In order to obtain RCAs with different initial AAR durations of 7, 28, 60, and 210 days. The specimens were then crushed using a jaw crusher. The residual reactivity of the RCA produced from concrete affected by the AAR was detected using the accelerated mortar bar test. The rheological properties of the SCRAC with different RCAs were tested. Compressive strength, flexural strength, mercury intrusion porosimetry, and scanning electron microscopy tests were conducted to analyze the effects of RCAs with different degrees of initial AAR damage on the mechanical properties and porosity of the SCRAC. The results show that the RCA can maximally strengthen the compressive strength of the SCRAC after 60 days of alkali immersion at a replacement rate of 30 %. Furthermore, a prediction model considering the filling effect for calculating the influence of RCAs with initial AAR damage on the compressive strength of the SCRAC was proposed. For practical engineering applications, the AAR can strengthen RCAs and improve the utilization rate of RCA, which is beneficial for the sustainable development of the environment.

Synchronization characteristics of two vibrator-driven pendulums

In this paper, a dynamic model with two vibrator-driven pendulums is presented. Each pendulum is motivated by a pair of vibrators mounted on it. According to the deduced synchronization criteria of the pendulums and the vibrators, the synchronous states of pendulums are determined by the phase differences of vibrators. The two pendulums achieve anti-phase synchronization when the phase differences of arbitrary-two vibrators are all stabilized around zero. If the phase differences of the two vibrators mounted on the same pendulum are zero whereas those on different pendulums are π, the pendulums will arrive at the in-phase synchronous state. Besides, the system shows a relatively good isolative effect under the anti-phase synchronous motion of the two pendulums. Based on the theoretical results, some numerical qualitative analyses are presented and simulations are implemented for verification. The dynamic model in this paper can offer guidance to design a kind of vibrating jaw crusher. Here, the two pendulums serve as movable jaws and work by the anti-phase synchronous swing motion trajectory.

Machine Learning Technics for Remaining useful Life Prediction using Diagnosis Data: a Case Study of a Jaw Crusher

Predictive maintenance currently involves digital transformation with all the technologies developed to serve the latter. This maintenance strategy is believed to be an efficient solution to end late/early intervention issues. It is for this reason that machine health state monitoring by Remaining Useful Life prognosis is very crucial. However, in the literature, most studies focus on failure diagnosis more than the system's Remaining Useful Life. In addition, to prepare models to serve the prognosis, the use of actual machinery data is critical to assure the later scalability of the application. The literature about predictive maintenance has often evaluated data-driven approaches with machine learning techniques processing simulated Data rather than real ones. To tackle this problem, the authors propose a continuity of previous work treating a jaw crusher default diagnosis in the context of the ore mining industry. The RUL of the crusher components is estimated upon completion of the fault diagnosis data. Smart sensors Data have been preprocessed to serve the evaluation of four regression machine learning models: Bayesian Linear Regression, Poisson Regression, Neural Network Regression, and Random Forest. Poisson regression and Neural Network required data normalization in this case study to improve their performance. Linear regression methods proved their inability to forecast the machine degradation state, while the bagging ensemble method, Random Forest, was able to track the actual values. This paper aims to enhance the Prognosis and Health Management of the machine while contributing to the literature enhancement on failure prognosis using real industrial data. Keywords— Data-driven approach, Industry 4.0, Machine learning, Predictive Maintenance, RUL prognosis, Smart sensors.

Preparation of phosphogypsum (PG) based artificial aggregate and its application in the asphalt mixture

How to massively consume phosphogypsum (PG) has attracted worldwide attention since this industrial by-product occupies considerable land resources and causes serious environmental problems. This study adopted PG to partly prepare the artificial aggregate to replace the natural aggregate in the asphalt mixture. The disk granulation and the jaw crusher produced two aggregates (D and C). Morphology, strength, internal structure and hydration products of the aggregate were characterized, and its influences on the properties of asphalt mixture were also evaluated. The optimal composition of the aggregate was recommended with a high PG utilization rate (80%) and sufficient strength. Both C and D aggregates had a low level of texture and were not suggested to be used on the surface layer of asphalt pavement. C aggregate had an excellent angularity and imparted the asphalt mixture with a better rutting resistance than D aggregate did. However, C aggregate easily got crushed during the Marshall compaction. The continuous hydration of D aggregate improved the moisture resistance of the mixture. Since it decreased the fracture energy of the mixture, especially at low temperatures, the artificial aggregate was not suitable to be used in the cold region. Overall, the PG-based artificial aggregates can partly replace the natural aggregate to be used in the asphalt mixture. This technology could be an economical alternative for massively consuming PG and saving natural resources.

Optimisation of the swinging jaw design for a single toggle jaw crusher using finite element analysis

Optimisation of the swinging jaw design for a single toggle jaw crusher using finite element analysis

Simulation of Energy Consumption in Jaw Crusher Using artificial intelligence models

Crushing is an important operation in a variety of industrial applications since it requires a significant amount of energy to blast materials into certain sizes of shattered boulders. Because accurate predictions of the energy required to manage this process are rare in the literature, there have been few efforts to reduce power consumption at the crushing stage by using a jaw crusher, which is the most common type of crusher. The availability of precise power predictions, as well as the optimization of initial crushing processes, would provide useful tools for selecting the best crusher for a given application. The Adaptive Neuro-Fuzzy Interference System is used to predict the particular power consumption of a jaw crusher in this study (ANFIS). Apart from the power required for rock comminution, the analysis includes an optimization of the crushing process to lower the projected power. In comparison to real data, the results show that the model is successful in correctly estimating comminution power with an accuracy of more than 96%. The findings provide valuable information that can be applied to future studies.