Primary Crushing Research Articles

Preliminary Research to Assess the Possibility of Grinding Selected Plastics Using Crushers

This study aims to investigate the effect of the shredding machine used on the recyclability of plastic fractions after primary crushing. This work presents a method for producing aggregates that has yet to be used in the plastics industry. This study included crushing of polymethylmethacrylate (PMMA), polyamide (PA-6), acrylonitrile butadiene-styrene (ABS), polycarbonate (PC), polystyrene (PS), and polypropylene (PP) waste in a jaw, a hammer, and a cone crusher. An analysis of the grain composition was carried out to characterize the obtained crushing products. The influence of feed size on the grain composition of the product and, only on the jaw crusher, the influence of the material used on the parameters of the crushing process was studied. This paper proposes a method to evaluate the grain composition and a way to assess plastic shredding capabilities based on machine kinematics and mechanical properties of a given material.

SIZE DISTRIBUTION OF JAW CRUSHER CRUSHING PRODUCTS FOR ROUNDED MATERIAL

Abstract — Crushing is one of stage material size reduction in mineral processing. Jaw Crusher is one of the equipment that used to reduction size material and it’s generally used in primary crushing. Feed of crushing is come from mined material (Run of Mine-ROM) that have various shapes like very rounded, rounded, angular etc. Rounded material is one of them. The aim of this research is to calculate the size distribution and the pattern of size distribution product of crushing for rounded material. The equipment of crushing in this research was used Jaw Crusher in Mineral Processing Laboratory, Institut Teknologi Nasional Yogyakarta which 30 samples material. The same pattern of size distribution was obtained from the +4#, -4#+10#, -10#+20#, -20#+40#, -40#+60#, -60#+100#, -100#+200# dan -200# product size distribution. The biggest amount of size distribution was obtained in 4#. Limiting Reduction Ratio (LRR) were distributed in range 4-6. Losses percentage (% losses) of material crushing were less than 10%. Keywords: Crushing, limiting reduction ratio, losses, mineral processing, primary

Tools for the Involvement of Construction and Demolition Waste in the Repeated Production Cycle

Purpose. This paper aims to analyze and classify construction and demolition waste. It is necessary that this classification not only reflects statistical data on waste generation, but also serves as an information basis for the integrated waste management system (IWMS). The main task of this system is to maximize the involvement of waste in economic recycling and to objectively reflect the technological capabilities of its processing. This is extremely important in the context of the implementation of European waste management principles and the implementation of the National Waste Management Strategy in Ukraine until 2030. Methodology. The article considers the problems of construction waste management within the framework of the National Waste Management Strategy in Ukraine until 2030, which provides for the implementation of measures and principles of waste management, including construction waste. The author analyzes the management problems in the field of construction and demolition waste, which substantiates the need to classify construction waste with the simultaneous harmonization of processing methods and technologies. Construction activities are inextricably linked to the management of various types of resources, among which secondary materials play a key role in the implementation of construction processes. The ability to effectively manage the flows of these secondary resources is critical to ensuring the sustainability and efficiency of construction production. In this context, the study of the importance of managing the flows of secondary resources becomes an integral part of strategies for optimizing construction processes. Findings. Construction waste from the demolition of buildings and structures is unique due to its size and the need to prepare it for primary crushing. This is especially true in the context of implementing the concept of renovation of the outdated housing stock. Various static and dynamic methods of destruction of building materials, in particular, impact and vibration, have been investigated, with dynamic methods being characterized by lower energy consumption. Originality. The work reflects the formation of theoretical and methodological directions based on the use of recycled materials in construction, as well as a comparative characterization of various methods of destruction of building materials. Practical value. The possibilities of recycling construction waste, in particular, their maximum involvement in recycling, which meets the goals of the Strategy of Ukraine, provides 50% of waste recycling.

Numerical simulation of jet atomization process of swirl nozzle

As the initial conditions of evaporative combustion, the jet atomization formed by the swirl nozzle has the characteristics of large distribution space and small atomization particle size, which is very important for the study of the jet atomization of the swirl nozzle. In this paper, the cross-scale VTD model is used to comprehensively consider the actual situation of multi-scale and multi-phase flow coupling in the atomization process. The evolution process and the breaking shape of the rotating cone liquid film during the atomization and crushing process are studied. The results show that the complete broken shape formed by the rotating cone liquid film can be divided into three areas along the axial direction: continuous liquid film, primary crushing, and secondary crushing. Among them, the appearance of irregularly distributed small holes is a significant feature of primary crushing. The sign of secondary crushing is that the liquid filaments are broken into small-scale droplet particles; after the primary and secondary crushing, the fully developed cone-shaped liquid film will appear to move up the position of the primary crushing cavity and reduce the scope. At the same time, the initial position of the secondary crushing will move up.

A Mine-to-Crusher Model to Minimize Costs at a Truckless Open-Pit Iron Mine in Brazil

Innovation has an important role in improving the productivity, safety and sustainability of mining operations. Historically, ore transport was done by diesel trucks, but with the commitment to reduce CO2 emissions and increase mine safety, mining companies have invested in innovative, more sustainable ore transport technologies. The innovative truckless system, with the intensive use of belt conveyors to transport the ore from the mine to the processing plant, represents a huge project and capital investment. However, operation costs are lower when considering the decrease of fuel use and also maintenance expenses. This paper presents an economic analysis of a mine-to-crusher model to estimate and minimize the operating expenses of an open-pit iron mine located in northern Brazil. The activities at this truckless mine consist of drilling and blasting, loading and primary crushing. In this study, the calibration of the mine-to-crusher model was based on rock fragmentation from the blasting phase. The costs of each mine operation phase were estimated for an optimum 80% passing size (P80). The calibration was conducted with the values of technical and economic parameters in 2019. By considering the structural lithologies of canga and jaspillites, we concluded that the P80 value that minimizes costs might be in the range from 0.31 to 0.34 m.

A State-of-the-Art Review on Suitability of Granite Dust as a Sustainable Additive for Geotechnical Applications

The increase in infrastructure requirement drives people to use all types of soils, including poor soils. These poor soils, which are weak at construction, must be improved using different techniques. The extinction of natural resources and the increase in cost of available materials require us to think of alternate resources. The usage of industry by-products and related methods for improving the properties of different soils has been studied for several years. Granite dust is an industrial by-product originating from the primary crushing of aggregates. The production of huge quantities of granite dust in the industry causes severe problems from the handling to the disposal stage. Accordingly, in the civil engineering field, the massive utilization of granite dust has been proposed for various applications to resolve these issues. In this context, the present review provides precise and valuable content on granite dust characterization, its effect as a stabilizer on the behavior of different soils, and its interaction mechanisms. The efficacy of the granite dust in replacing sand in concrete is explored followed by its ability to improve the geotechnical characteristics of clays of varying plasticity are explored. The review is even extended to study the effect of binary stabilization on clays with granite dust in the presence of calcium-based binders. The practical limitations encountered and its efficiency over other stabilizers are also assessed. This review is further extended to analyze the effect of the granite dust dosage for various field applications.

Rock Fragmentation Evaluation towards Blast-To-Mill Concept of Blast Optimization in Hard Rock Mines

Traditional blast optimisation studies ensure efficient mining operation but ignore potential impact of blasting on primary crushing. The performance of the primary crusher is key to the ore beneficiation process. Optimisation studies conducted through the mining operations to the comminution circuit is vital to the mine-to-mill concepts in the mining industry. In this approach, an innovative approach to the assessment of in-situ blasting is proposed and evaluated. This approach focuses on the acceptability of rock fragments on the Run-of-Mine (ROM) pad as opposed to the pits. Fragmentation analysis was conducted in the pit and on the ROM pad. A correlation efficiency of 0.92 was realized between the measured rock fragments in the pit and that on the ROM pad. About 10% of the rock fragments in the pit were classified as boulders while about 30% of the same rock fragments deposited on the ROM pad were classified as boulders. However, about 30% of the rockpile on the ROM pad was estimated to be lower than the Close Side Setting (CSS) of the primary crusher. It is recommended that future research evaluates the energy consumption and its related cost at the primary crusher in comparison to in-pit fragmentation and mucking cost performance.

Analysis of the techniques for assessing the features of blast-induced fragmentation in an open pit quarry

The paper deals with the study of empirical models for the analysis of blasts-induced fragmentation. To verify the reliability of the method, the results obtained a priori through the application of the models are compared with the analyses of muck piles photos taken from a series of blasts in an open pit quarry, thanks to the Split-desktop software (Split Engineering, LLC, Tucson, USA). The study of the particle size distribution is very important when sizing an excavation site, as the average size of the pile must be compatible with the equipment used for clearing and conveyance, and with the first phase of the processing plant, i.e. primary crushing. After a description of the excavation technique in use at the quarry site, its main characteristics are outlined. The parameters used to create the empirical models refer to the geomechanical characteristics of the rock, the geometry of the blasts, the characteristics of the explosive and its interaction with the rock mass, paying attention to the correlation between initiation timing and induced fragmentation. A detailed description of some empirical models together with the Split-desktop software were therefore provided. Thanks to both data and photos of the muck-piles from the exploitation at the quarry, the particle size curves resulting from each model were compared with those obtained from the software. This allowed to validate the empirical method in a preliminary design phase.

Improvement of primary crushing technology for Stoilensky ferruginous quartzite using updated gyratory crushers manufactured KKD-1500/180

Primary crushing is one of the critical stages in mineral processing, which governs efficiency and capacity of the follow-on ore pretreatment. Given the present-day activity of Stoilensky GOK toward an increase in production capacity and efficiency, improvement of primary crushing is the first-order condition of the strategic mission accomplishment. This article describes the primary crushing productivity enhancement project at Stoilensky GOK through retrofitting of primary gyratory crushers manufactured at Uralmashplant, which has ensured the annual production output of 38 Mt/yr. The main engineering solutions on redesign of crushers KKD-1500/180, aimed at enhanced capacity and optimization of end product size in the conditions of coarse grinding shopfloor at Stoilensky GOK, consist in optimization of ore feed, intensification of crushing effect and primary breaking in the upper zone of crusher chamber, as well as in improvement of functioning of heavy-duty friction assemblies of crushers. The in-proof test conditions, methods and results obtained after modernization of crushers KKD-1500/180 are presented. The implementation of modernization solutions ensured the hourly efficiency increase from 400 to 5563 t/h at the product outlet width of 180 mm. The grain size composition evaluation proved the product quality improvement connected with stable size and reduction of medium size of the crushed product to d05 = 232.65 mm. As a consequence, it is possible to enhance capacities in the next following stages of medium and fine grinding due to better ore pretreatment quality.

Integrated Device for Collection of Garden Waste and Production of Auricularia Auricula Medium

With the acceleration of greening process in China, the output of garden greening waste is also increasing, but the treatment method of greening waste is single and the utilization degree of resources is low. Therefore, this work puts forward a method that integrates waste collection and Auricularia auricula culture medium production. Taking garden waste as raw material, the original material of Auricularia auricula culture medium is obtained through the process of collection, primary crushing and secondary crushing, and mixing ratio process. After simple packaging and subsequent sterilization and disinfection process, the regenerated Auricularia auricula culture medium is made.

Experimental investigation into performances of an active Whipple shield against hypervelocity impact

With the continuous increase of centimeter-scale space debris, the exploration and design of new high-performance shields has become an urgent need. Based on the shield of active materials, the hypervelocity impact experiments with different projectile sizes and impact velocities were carried out by using a two-stage light gas gun. The image characteristics of debris clouds under different impact conditions were obtained and analyzed by laser shadowgraph photography. The damage characteristics of the rear wall of the active Whipple shield were studied. Through the statistical analysis of the number of craters, the influences of active materials on the fragmentation of projectiles under different impact velocities were obtained. Compared with the classical Christiansen ballistic limit equation, the protective performance of energetic active material shield was obtained, and the ballistic limit curve of the new shield was fitted. Analysis suggests that shock initiation characteristics of active materials under impact enhanced the shield performance. When impacted by the space debris, active material shield firstly uses its mechanical strength for primary crushing. During this process, the energetic material shield has an explosive reaction with an instantaneous temperature being as high as 3 800 K, which can promote fragmentation, melting and reduce the size of the space debris. At the same time, the explosion products with high temperature, pressure and high speed motion produce a negative acceleration to the projectile fragments, reducing the axial kinetic energy. The explosion products of the active materials are mostly gaseous, which greatly reduce the number of the fragments with penetration ability in the debris cloud. The penetration failure of the rear plate only comes from the fragments generated by the fragmentation of the projectile. Under the combined action of impact and explosion, the active materials shield can not only fully break and decelerate space debris, but also greatly reduce the number of solid debris in debris cloud, thereby produce a sharp rise in the spacecraft protection ability, and the maximum protection ability can be increased by 45% when the velocity is 2.31 km/s.

A methodology for designing cutting drum of surface miner to achieve production of desired chip size

The size of coal chips, produced during coal cutting operations, is of prime importance from the viewpoint of feed size desired by power plants. Proper chip size in cutting can eliminate primary crushing and in-turn save energy. Achieving a designated size of chip is intimately linked with the drum design inter alia the wrap angle, line spacing of picks and pick size. Operating parameters namely cutting speed and drum speed also influence the output. Considering the increased need to produce a sized product for cost-effective mining, a design methodology was developed to achieve a required chip size for surface miners with a middle drum configuration. Various pick, drum and operational parameters were taken into account for the development of drum design, namely drum width, drum diameter, pick size, clearance angle, rake angle, cutting angle, lacing pattern, angle of wrap, depth of cut, indented depth of cut and pick spacing. Limiting factors for drum design such as the number of picks, pick temperature, strength of pick, depth of cut and dust generation were discussed. A new drum configuration for achieving 100 mm chip size was validated which showed close agreement with the output produced using 2200SM model surface miner.

Development and implementation of key performance indicators for aggregate production using dynamic simulation

Continuous process improvements are needed to maintain and run an industrial operation at a profitable state. An aggregates production plant consists of multiple process operations such as blasting, primary crushing, followed by secondary and tertiary crushing stages with an intermediate screening of products. Each of these processes can be operated with multiple objectives in mind of operators and plant managers. These objectives can be defined by varying terms like generating required throughput of the plant, maintaining equipment’s health, meeting customers’ demands, etc. The use of the term key performance indicators is recurrent in industry to formalise and represent these objectives of operation. Currently, the KPIs defined by the ISO 22400 standards are widespread for continuous improvements in the manufacturing industry and they are viewed as a support tool to measure improvements. The scope of this paper is to calculate relevant KPIs for an aggregates production plant using dynamic simulations. Further, the KPIs are implemented in a three-stage aggregate production plant using both real-time plant data and dynamic process simulation. The KPIs developed are useful for operators and plant managers to make decisions. The results show the relationship and dependencies of various equipment and process KPIs. The dynamic simulation has potential to be used as an exploration tool to identify the opportunities of improvement in aggregates processing using KPIs as a measure. The KPIs presented in the paper are based on ISO 22400 standard and have potential to be extended to similar processing operations such as coarse and fine comminution for minerals processing. Apart from the diagnostics application, the KPIs implemented in the dynamic simulation platform can be used to explore and optimize a crushing plant’s design and operations.

Modofication of the Sarcheshmeh copper complex flotation circuit in response to a reduction in feed grade

The new copper processing plant of the Sarcheshmeh copper complex consists of two parallel circuits. After a primary crushing, the ore is sent to a SAG mill, and the product is further ground in a ball mill. The overflow of the hydrocyclones is fed to a flotation circuit that contains 8 rougher tank cells (RCS130), 3 cleaner cells (RCS50), 5 scavenger cells (RCS50), and a flotation column (as recleaner). The circuit was initially designed to process a feed containing 0.8% Cu but due to a change in the ore type, the feed grade decreased to 0.6% Cu. This resulted in a reduction in the final concentrate grade and the recovery from 28% and 85.5% to 24% and 84.4%, respectively. Based on the original design, the copper and silica recovery in the cleaner cells should be 69% and 55%, respectively, but these values increased to 85% and 75% due to a higher retention time. The rather high silica recovery was found to be the main source of the lower final concentrate grade. In order to reduce the retention time of particles in the cleaner cell from 13.7 to 6.9 min, the rougher concentrates of two parallel circuits were fed to only one cleaner-scavenger and regrind circuit. This modification increased the cleaner and final concentrate grade from 15.1% and 24.5% to 17% and 26%, respectively. The overall outcome of the circuit modification was evaluated to be a 10% reduction in the energy consumption without any loss in the overall copper recovery.

An industrial example of using Enterprise Architecture to speed up systems development

AbstractThe development of large, complex, heavy construction equipment can be difficult, time consuming and expensive, even more so if the goal is to design a complete site solution. The example used is taken from an ongoing real project named Electric site. The aim is to electrify a transport stage in a quarry – from excavation to primary crushing and transport to secondary crushing. This will reduce the CO2 95% and the total cost of operation 25%. This paper describes how a standards‐based enterprise architecture model can be used to significantly influence continued system engineering efforts as well as the software architecture for the application development. The enterprise architecture model has been developed specifically to ensure overall management of the site. It is this description, created with an enterprise perspective of the site that is used directly to speed up the development of the systems architecture. The model also details the applications that are required as part of the different systems that will support the overall management of the site.

Analysis of the treatment of plastic from electrical and electronic waste in the Republic of Serbia and the testing of the recycling potential of non-metallic fractions of printed circuit boards

This paper presents the analysis of the quantity of plastic and waste printed circuit boards obtained after the mechanical treatment of electrical and electronic waste (E-waste) in the Republic of Serbia, as well as the recycling of non-metallic fractions of waste printed circuit boards. The aim is to analyze the obtained recycled material and recommendation for possible application of recyclables. The data on the quantities and treatment of plastics and printed circuit boards obtained after the mechanical treatment of WEEE, were gained through questionnaires sent to the operators who treat this type of waste. The results of the questionnaire analysis showed that in 2014 the dismantling of E-waste isolated 1,870.95 t of plastic and 499.85 t of printed circuit boards. In the Republic of Serbia, E-waste recycling is performed exclusively by using mechanical methods. Mechanical methods consist of primary crushing and separation of the materials which have a utility value as secondary raw materials, from the components and materials that have hazardous properties. Respect to that, the recycling of printed circuit boards using some of the metallurgical processes with the aim of extracting copper, precious metals and non-metallic fraction is completely absent, and the circuit boards are exported as a whole. Given the number of printed circuit boards obtained by E-waste dismantling, and the fact that from an economic point of view, hydrometallurgical methods are very suitable technological solutions in the case of a smaller capacity, there is a possibility for establishing the facilities in the Republic of Serbia for the hydrometallurgical treatment that could be used for metals extraction, and non-metallic fractions, which also have their own value. Printed circuit boards granulate obtained after the mechanical pretreatment and the selective removal of metals by hydrometallurgical processes was used for the testing of the recycling potential. Granulometric analysis as well analysis of chemical composition of obtained fractions was performed. Subsequently, the manual classification of different types of polymeric material contained in the granulate was made, and both the apparent specific gravity and the chemical composition of the classified types of polymeric materials were determined. Chemical composition of granulate was determined by X-Ray Fluorescence (XRF) using Thermo Scientific Niton XL 3t, while the identification of residual polymers was determined by the FTIR (Fourier Transform Infrared Spectroscopy) method on the Bomen MB 100 device in range 4000 to 400 cm?1. Based on the results of this study, it can be concluded that after the hydrometallurgical treatment of printed circuit boards, and the separation of metals that have the highest value, the residual non-metallic fraction have the utility value and can be used for various purposes, such as developing new polymer materials for technical purposes that have been investigated by many researchers and mentioned in this article.

Mechanical pre-treatment of mobile phones and its effect on the Printed Circuit Assemblies (PCAs)

The recycling of Waste Electrical and Electronic Equipment (WEEE) has attracted a notable amount of interest during the last few decades due to the high metal concentrations and substantial increase in the growth rate of WEEE. In addition, higher recovery and recycling rates required by the European Union demand more comprehensive treatment of WEEE. However, complex product design and the presence of harmful substances together with low concentrations of special metals present challenges for processing. This study examines the effect of mechanical treatment of mobile phones on metal concentrations in the printed circuit assembly (PCA) fraction compared to manual dismantling. The designed mechanical treatment process including crushing, sieving, magnetic-, eddy current- and sensor-based separation was able to separate plastics, ferrous metals, PCA and stainless steel for further treatment. The process separated PCA with an efficiency of 85%. However, the quality of the separated PCAs was poor compared with “pure” manually dismantled PCAs. The primary crushing of mobile phones destroys PCAs thus resulting in the loss of especially precious metals used in the connector coatings and in the surface-mounted components. As a result, the theoretical value of the produced PCA fraction is only half compared to using manual dismantling. However, high labour costs in western countries and low capacity may hinder the feasibility of hand dismantling.

Influence of the Crushing Process of Recycled Aggregates on Concrete Properties

This work intends to evaluate the (mechanical and durability) performance of concrete made with coarse recycled concrete aggregates (CRCA) obtained using two crushing processes: primary crushing (PC) and primary plus secondary crushing (PSC). This analysis intends to select the most efficient production process of recycled aggregates (RA). The RA used here resulted from precast products (P), with strength classes of 20 MPa, 45 MPa and 65 MPa, and from laboratory-made concrete (L) with the same compressive strengths. The evaluation of concrete was made with the following tests: compressive strength; splitting tensile strength; modulus of elasticity; carbonation resistance; chloride penetration resistance; capillary water absorption; and water absorption by immersion. These findings contribute to a solid and innovative basis that allows the precasting industry to use without restrictions the waste it generates.

Performance of concrete made with aggregates recycled from precasting industry waste: influence of the crushing process

The aim of this paper is to evaluate the influence of the crushing process used to obtain recycled concrete aggregates on the performance of concrete made with those aggregates. Two crushing methods were considered: primary crushing, using a jaw crusher, and primary plus secondary crushing (PSC), using a jaw crusher followed by a hammer mill. Besides natural aggregates (NA), these two processes were also used to crush three types of concrete made in laboratory (L20, L45 e L65) and three more others from the precast industry (P20, P45 e P65). The coarse natural aggregates were totally replaced by coarse recycled concrete aggregates. The recycled aggregates concrete mixes were compared with reference concrete mixes made using only NA, and the following properties related to the mechanical and durability performance were tested: compressive strength; splitting tensile strength; modulus of elasticity; carbonation resistance; chloride penetration resistance; water absorption by capillarity; water absorption by immersion; and shrinkage. The results show that the PSC process leads to better performances, especially in the durability properties.

Particle damage and exposure analysis in HPGR crushing of selected copper ores for column leaching

In mining operations, jaw and gyratory crushers are generally used for primary crushing, and cone crushers are used for secondary crushing. During the past decade, however, high-pressure grinding rolls (HPGR) are being considered due to potential processing benefits such as energy savings, improved exposure/liberation and particle weakening. At this time there is no detailed quantification of particle damage and downstream benefits from HPGR crushing are uncertain. In the present research, copper ores (copper oxide ore and copper sulfide ore) were crushed by a jaw crusher and by HPGR and the products were evaluated for particle damage and copper grain exposure by X-ray computed tomography. Column leaching was done to determine the rate and extent of copper recovery. X-ray computed tomography analysis and laboratory column leaching experiments for copper oxide ore revealed that products from HPGR crushing have more particle damage and higher copper recoveries when compared with products of the same size class from jaw crusher crushing. Generally the copper recovery from column leaching of the oxide ore was found to be dependent on the extent of grain exposure, which increases with a decrease in particle size. In the case of the copper sulfide ore, copper recovery was found to be independent of the crushing technique despite the fact that more particle damage was observed in products from HPGR crushing. This unexpected behavior for the copper sulfide ore might be due to the high head grade and strong leach solution. Column leaching results also show that about 80–90% of the copper was recovered from the copper sulfide ore in a relatively short leaching time irrespective of crushing technique. As expected, copper recoveries improved with a decrease in the particle size of the copper sulfide ore as exposure of copper mineral grains increased.