High and medium-pressure roller crushers operate on the principle of inter-particle crushing by crushing material in a packed bed. Although reference in the study is made to high-pressure roller crushers, the work was done with medium–pressure roller crushers i.e. the Loesche mill and the Horomill. The difference in pressures between these equipment and high-pressure grinding rolls (HPGR) from measurements done by FCB, the supplier of the Horomill, was that the medium-pressure equipment operates at pressures of 30 MPa whilst the HPGR operates at pressures as high as 100 MPa. In this study, the differences between single particle and inter-particle crushing and the applicability of the batch press to predict the energy consumption and particle size distributions for medium-pressure roller crushers were investigated. Two phases of crushing were identified and investigated. The first phase occurs when the material is still being drawn into the gap between the rollers. The second phase, called packed bed crushing, occurs when the material is in the gap between the rollers. Crushing and milling energy requirements are discussed with specific reference to the energy models proposed by Bond and Rittinger along with the shortcomings of both these models. These models postulate that the comminution energy is an inverse function of product size. This is proven to be true in this study, but where certain constants are suggested in the aforementioned correlations, this study revealed that these constants are not fixed for all applications but varies for different types of ore. The results were determined for 80% as well as 50% mass passing size. Kick proposed that the energy requirements are a function of the reduction ratio. A model used for roller crushers that is similar to what Kick proposed was also investigated. This was also found to be valid but again, the coefficients in the model vary for the different materials. A new method for predicting the work index of an ore for inter-particle crushing was investigated, which involves using a piston press in which a bed of material is pressed to a predetermined pressure. The proposed method was evaluated using pilot test data obtained with a Horomill, as well as with a pilot Loesche mill. The results indicate that the correlation between the batch press and the pilot mills are poor. The Rosin-Rammler description for particle size distribution was applied and compared with other descriptions. The particle size descriptions of products from the batch press and pilot mills were compared and although there are differences, the batch press can be used to prepare material for initial research in a project. From this study it is clear that, especially when tests are done on an unknown ore body, a work index such as Bond’s, cannot be used for plant design and economic studies unless some pilot plant tests are done to confirm the relationship between energy consumed and product size. / Dissertation (MEng)--University of Pretoria, 2012. / gm2014 / Materials Science and Metallurgical Engineering / unrestricted

Šiame darbe pateikta gluosninių žilvičių auginimo, ruošimo bei naudojimo analitinė apžvalga, gluosnių auginimo technikos ir technologijų energetinis vertinimas, nesubrendusių gluosnių pjaustinio ilgio teoriniai tyrimai naudojant žolinių augalų smulkintuvą. Taip pat eksperimentiškai nustatytos gluosnių fizikinės – mechaninės savybės, poveikis aplinkai deginant skirtingo pjaustinio gluosnius. Tyrimai atlikti naudojant 10 kW biokuro katilą, skirtą kūrenti energetinių augalų skiedroms, briketams, paletėms. Nustatytos kenksmingų medžiagų (CO2 , CO, NO, NOx) emisijos į aplinką deginant skirtingo tipo smulkintuvais susmulkintus gluosnius. / In this work the willow cultivation, preparation and use of analytical review of willows growing energy technology and technology assessment in juvenile willow cuttings-length adaptation of the theoretical studies of herbaceous plants shredder. It is well established experimentally rushes physical - mechanical properties of the environmental impact of combustion of different willow cuttings. Investigations were carried out using a 10 kW biofuel boiler to burn energy crops for wood chips, briquettes, pallets. Down (CO2 , CO, NO, NOx) emissions into the environment by burning different types of chopped willow cutter.

Submitted by Kilvya Braga (kilvyabraga@hotmail.com) on 2018-04-23T10:51:37Z No. of bitstreams: 1 EMYDIO CLEMENTE DE SOUSA NETO - DISSERTAÇÃO (PPGEM) 2015.pdf: 5264287 bytes, checksum: 48883828373d3daac0f65ee6e1ef7809 (MD5) / Made available in DSpace on 2018-04-23T10:51:37Z (GMT). No. of bitstreams: 1 EMYDIO CLEMENTE DE SOUSA NETO - DISSERTAÇÃO (PPGEM) 2015.pdf: 5264287 bytes, checksum: 48883828373d3daac0f65ee6e1ef7809 (MD5) Previous issue date: 2015-07-31 / O desgaste prematuro de conjuntos e componentes industriais, bem como de uma infinidade de outros segmentos, representa um grande fator para a redução da eficiência operacional de um equipamento, provocando assim, um aumento das perdas, e consequentemente, em altas despesas com manutenção e reposição de componentes mecânicos. Este trabalho aborda uma análise comparativa entre a resistência ao desgaste de martelos trituradores de baterias recuperados por três ligas a base de cobalto (Stellite 1, 6 e 21), bem como dois processos de deposição: os processos ao Arco Elétrico com Eletrodo Revestido (SMAW) e ao Arco Plasma Transferido com adição de Pó (PTA-P). Os martelos trituradores são originalmente confeccionados em aço inoxidável AISI 316 L sem nenhum recobrimento. Além da avaliação da resistência ao desgaste no próprio meio de trabalho foram realizados ensaios de microdureza, análises microestruturais via microscopia ótica, e eletrônica de varredura e, análise de diluição com o objetivo de caracterizar e consolidar a pesquisa para que se tenha o estudo comparativo da melhor liga e melhor processo de deposição. Os resultados demostraram que a melhor condição testada foi aquela que empregou a liga Stellite 6 depositadas pelo processo PTA-P. Essa condição apresentou a menor perda de massa nos ensaios de resistência ao desgaste, enquanto que a condição menos favorável foi verificada para os depósitos executados com a liga Stellite 1 utilizando o mesmo processo de deposição. A diluição média das ligas depositadas pelo processo SMAW foi 3,7 vezes maior do que a média apresentada utilizando o processo PTA-P. Os maiores valores de microdureza foram aqueles apresentados pelo revestimento executados com a liga Stellite 1 com maior teor de C, e esta liga, proporcionou um maior número de destacamento dos revestimentos. A microestrutura dos depósitos executados pelo processo PTA-P apresentou-se mais refinada quando comparada com aquelas depositadas pelo processo SMAW. / The premature wear sets and industrial components, as well as many of other segments, is a big factor for reducing operational efficiency of equipment, thus causing an increase in losses, and consequently in high cost of maintenance and replacement of mechanical components. This work presents a comparative analysis of the wear resistance of AISI 316 L steel automotive batteries crushers hammers repaired by welding process using three cobalt-based alloys: Stellite 1, 6 and 21, as well as, two welding deposition process: Shielded Metal Arc Welding (SMAW) and Plasma Transferred Arc with addition powder (PTA-P). Crushers hammers are originally made of stainless steel AISI 316 L with no coating. Besides the “in situ” wear resistance evaluation microhardness tests, microstructure and dilution analysis by optical microscopy and scanning electron were done to characterize and consolidate research in order to have a comparative study of best league and better deposition process. The results showed that the best alloy was Stellite 6 using the PTA-P process, which had the lowest mass loss in wear resistance tests, while the less favorable condition was for deposits made with the alloy Stellite 1 using the same deposition welding process. The average dilution of the alloys deposited by the SMAW process was 3.7 times higher than the average using the PTA-P process. The highest microhardness values were presented by Stellite 1 alloy deposit, with higher C content, which also provided a greater number of coating detachment. The deposits made by the process PTAP showed a more refined microstructure when compared to those deposited by the SMAW process

The aim of this thesis is the design of laboratory crusher of mineral raw materials. This work is focused on the research of possible types of machinery for crushing process, list of shredders available at domestic and foreign markets, selection of the principle of diminution of mineral resources, the choice of approach, suggestion of calculation of the chosen design, creating a 3D model and drawings, making the strength analysis for selected parts, risk analysis.