This diploma thesis is concerned with design and proposal of parameters of drop hammer Davon for crushing of steel reinforced concrete panels with weight of the ram 5 t. The main topic is an emergency condition when there is no crushed material between ram and anvil. The design is established by simulation of an impact by finite element analysis with respect to required ground bearing capacity.

Mamelodi Quarries, which currently mine the Franspoort nepheline syenite, produces aggregate and crusher sand for the local building industry. The mine is located northeast of Pretoria, South Africa on the road to Cullinan. The aim of this study is to investigate the use of the Franspoort nepheline syenite as an alumina and alkali resource for the glass and ceramics industry at Mamelodi Quarries, and to evaluate the production of a concentrate of zircon and rare earth elements as economic by-products. International standards require a nepheline product with a ferric oxide content of less than 0.35 weight percent. The Franspoort nepheline syenite contains 3.37 weight percent of ferric oxide. The iron-containing minerals present are aegirine, aegirine-augite, magnetite, ilmenite and pyrite. The removal of iron-bearing minerals was attempted by high-intensity wet magnetic separation, low-intensity dry magnetic separation, spiral gravity separation, and heavy liquid separation to produce a saleable nepheline product. This product is the cleaned final concentrate, of the different separation tests, which contains the lowest iron concentration for application in the glass and ceramic industry. The mineral assemblage was determined with a petrographic study as well as X-ray diffraction and electron microprobe analyses. Material from the different separation tests was analysed with X-ray fluorescence to obtain the chemical composition and to evaluate the final iron content of the nepheline product. The dry magnetic separation method produced the best results. The nepheline product has a ferric oxide content of 0.68 weight percent compared to the starting concentration of 3.37 weight percent. The ferric oxide concentration is, however, above the accepted levels for the glass and ceramics industry. The ferric oxide content is attributed to small iron-rich mineral inclusions, which are locked in feldspar and nepheline. The final nepheline product is not suitable for the use in the glass and ceramic industry. Zircon was concentrated the best by the use of heavy liquid separation. Zircon is in most cases locked in the minerals albite, microcline, and nepheline. The rare earth elements are mostly associated with zircon and fluorite and therefore it will not be viable to produce it as a by-product. Copyright / Dissertation (MSc)--University of Pretoria, 2010. / Geology / unrestricted

Für die Weich- und Mittelhartzerkleinerung von Primär- und Sekundärrohstoffen werden zunehmend Profilwalzenbrecher eingesetzt. Trotz relativ geringer Zerkleinerungsgrade zeichnen sie sich durch einen geringen spezifischen Leistungsbedarf, hohe Durchsätze, eine einfache Konstruktion und Instandhaltung sowie eine störungsfreie Betriebsweise aus und sind auch bei adhäsivem Aufgabematerial anwendbar. Trotz der Bedeutung dieser Maschinen gibt es bisher nur unzureichende Auslegungsmethoden. Die theoretisch begründete Modellierung der Zerkleinerung in markant profilierten Walzenbrechern ist deshalb Gegenstand dieser Arbeit, um dadurch die Dimensionierungsgrundlagen zu verbessern und Einsatzmöglichkeiten in der Hartzerkleinerung abzuschätzen. Dazu werden im Rahmen einer Systembetrachtung zunächst die wesentlichen Prozessparameter der Zerkleinerung ermittelt und die Bauarten von Profilwalzenbrechern klassifiziert (Kapitel 2). Die Darstellung der bekannten Berechnungsmodelle für die Hauptzielgrößen „Grenzdurchsatz“, „Produktgranulometrie“ und „Leistungsbedarf“ ist Gegenstand von Kapitel 3. Darauf aufbauend wird in Kapitel 4 ein neues, physikalisch begründetes Auslegungsmodell vorgestellt und das Untersuchungsfeld hinsichtlich der zu analysierenden Aufgabestoffart und Maschinengeometrie eingegrenzt. Die für dieses Modell erforderlichen Zerkleinerungstest- und Simulationsergebnisse werden in Kapitel 5 und 6 dargestellt, bevor die Arbeit in Kapitel 7 mit einer Zusammenfassung und einem Ausblick abschließt.

Zur Auslegung von profilierten Doppelwalzenbrechern werden bisher recht einfache Modelle verwendet, wobei wichtige Einflussfaktoren unberücksichtigt bleiben. Daher werden im Rahmen dieser Dissertation auf Basis experimenteller Untersuchungen verbesserte Auslegungsmodelle für die wichtigsten Zielgrößen von Doppelwalzenbrechern entwickelt, welche präzisere Prognosen ermöglichen. Das Versuchsprogramm sieht dabei die Variation von Aufgabematerial sowie –partikelgröße, Walzenumfangsgeschwindigkeit und Spaltweite in einem großen Wertebereich vor. Das zur Prognose der Produktpartikelgrößenverteilung entwickelte Modell basiert dabei auf der Swebrec-Funktion. Mit diesem lässt sich abhängig von der Spaltweite und der Aufgabepartikelgrößenverteilung die Produktpartikelgrößenverteilung bestimmen. Des Weiteren kann mit Hilfe des in dieser Arbeit aufgestellten Bilanzmodells der Grenzmassedurchsatz unter Kenntnis der Masse¬anteile für beliebige Mischungen von Einzelfraktionen prognostiziert werden. Dabei werden auch übergroße, nicht sofort einziehbare Partikel berücksichtigt, welche den Durchsatz signifikant senken können.

Rock blasting is one of the most dominating operations in open pit mining efficiency. As many downstream processes depend on the blast-induced fragmentation, an optimized blasting strategy can influence the total revenue of a mine to a large extent.Boliden Aitik mine in northern Sweden is one of the largest copper mines in Europe. The annual production of the mine is expected to reach 36 million tonnes of ore in 2014; so continuous efforts are being made to boost the production. Highly automated equipment and new processing plant, in addition to new crushers, have sufficient capacity to reach the production goals; the current obstacle in the process of production increase is a bottleneck in crushers caused by oversize boulders. Boulders require extra efforts for secondary blasting or hammer breakage and if entered the crushers, they cause downtimes. Therefore a more evenly distributed fragmentation with less oversize material can be advantageous. Furthermore, a better fragmentation can cause a reduction in energy costs by demanding less amounts of crushing energy.In order to achieve a more favorable fragmentation, two alternative blast designs in addition to a reference design were tested and the results were evaluated and compared to the current design in Aitik. A comparatively large bench was divided to three sections with three different drill plans, which led to different specific charges in each section. The sections were drilled in patterns of 6x9 m, 7x9 m and 7x10 m of burden and spacing; planned specific charges of the sections were 1.17 kg/m3, 1.02 kg/m3, and 0.91 kg/m3 respectively. Similar to the current drill plan in Aitik, the section with 7x9 m (1.02 kg/m3 specific charge) was used as the reference for results comparison. The drilling and charging processes were monitored carefully and the post-blast parameters were measured accordingly. Laser scanning was used to measure the swelling of the sections and two different methods of image analysis were utilized to evaluate the fragmentation of the rock for each section. Drilling log data (MWD) were analyzed to evaluate the hardness of the rock; energy consumption log of the crusher was also analyzed and all the data was collected in a single database. VBA (Visual Basic for Applications) programming language was embedded within data spreadsheets to correlate the mentioned data to the coordinates of the rock by means of Minestar logs, which include both timestamps and coordinates of all machinery e.g. shovels and trucks.The results of the test show significant improvements in fragmentation and oversize material percentage in the section with 6x9 m drill plan (1.17 kg/m3). The advantage of 6x9 m plan was confirmed by 52% higher swelling, 66% lower oversize material and 26% lower crushing energy compared to the reference section. The section with 7x10 m drill plan (0.91 kg/m3) also showed theoretically acceptable results; however, the deviations from reference were not as large as formerly mentioned section. The swelling had a decrease of 8% compared to the reference section and the percentage of oversize material and crushing energy were increased by 16% and 2% respectively.Presented results are based only on technical aspects and do not include the costs of drilling and charging. Thus, in order to evaluate the drill plans in practice an economical evaluation of the sections should be conducted. Also a confirmation test with more accurate geology explorations is recommended.Finally, upon the request of Boliden Mines, a short report on the usage of Air-decking technique in Aitik is enclosed as an appendix. The report includes a brief introduction to air-decking and discusses practical solutions to apply this technique in Aitik. / Validerat; 20121001 (anonymous)

Etapas de cominuição representam uma grande parcela do capital e custo operacional em uma usina de processamento mineral. Em 1983, Cohen estimou que os processos de cominuição podem ser responsáveis por 30% a 50% do consumo energético da usina representando tipicamente 50% dos custos operacionais de uma mineração. Sendo assim, sua otimização está diretamente relacionada com a redução destes custos de operação. Entre os equipamentos de britagem, o moinho de martelos é aquele dedicado às operações que visam a alta taxa de redução com geração controlada de finos. Este britador é recomendado para minérios friáveis e pouco abrasivos, apresentando alta capacidade produtiva. O presente trabalho tem por objetivo propor e validar um modelo matemático para modelagem e simulação de moinho de martelos, visando a simulação do circuito da britagem industrial de beneficiamento de minério de ouro do Córrego do Sítio I, localizada em Santa Bárbara - MG. As simulações visaram identificar gargalos operacionais e estabelecer cenários que permitam otimizar o circuito estudado. A amostragem foi executada conforme o plano traçado. As amostras obtidas foram utilizadas tanto para a caracterização do minério quanto para a calibração do modelo do Caso Base da operação da usina. As simulações indicaram acréscimos significativos de vazão de alimentação na usina, a partir do aumento da velocidade de rotação do moinho de martelos, com uma tendência de geração maior de finos no processo. Para simulação do aumento de velocidade de rotação dos martelos foi criado um modelo com base na energia de quebra das partículas, associada aos incrementos correspondentes na energia cinética dos martelos. A fim de validar o modelo proposto, foram planejados ensaios específicos em moinho de martelos de laboratório, e executados com o mesmo minério alimentado na usina industrial selecionada. Os ensaios consistiram em variações de velocidade de rotação dos martelos, de forma a corresponder às simulações anteriormente realizadas do equipamento industrial. O modelo criado foi validado com base em campanha experimental específica. / Comminution represents a large portion of the capital and operating cost of a mineral processing plant. In 1983, Cohen estimated that comminution processes could account for 30% to 50% of the power consumption of the mill, and typically represents 50% of the operating costs of a mine. Therefore, its optimization is directly related to reduction of these operating costs. Among the crushing equipment, the hammer mill is one which is dedicated to operations that aim for high reduction ratio with controlled generation of fines. This crusher is recommended for friable and low abrasive ores presenting a high productive capacity. This study aims to develop a stepwise approach that allows the use of the classical crusher model (Whiten-Andersen) in modeling and simulation of circuits containing a hammer mill, simulating the resulting product according to variation of rotation speed within the equipment. The existing model for crushers developed by Whiten-Andersen considers the Perfect Mixing Model, which represents crushing through equations related to selection and breakage functions, that provide an equilibrium condition. The present work aims at the validation of a mathematical model of hammer mill, aiming at a simulation of the circuit of the industrial crushing of gold ore of Córrego do Sítio I, located in Santa Bárbara - MG. The simulations aimed at identifying operational bottlenecks and establishing scenarios that allow optimizing the studied circuit. Sampling was performed according to the drawn plan. The samples obtained were used both for the characterization of the ore and for the calibration of the Base Case model of the plant operation. The simulations indicated significant increases in feed flow at the plant, due to the increase in the speed of rotation of the hammer mill, with a trend of higher generation of fines in the process. To simulate the increase of rotational velocity of the hammers, a model was created based on the energy of breaking of the particles, associated to the corresponding increments in the kinetic energy of the hammers. In order to validate the proposed model, specific tests were planned in laboratory hammer mill, and executed with the same ore fed in the selected industrial plant. The tests consisted of variations in the speed of rotation of the hammers, in order to correspond to the previous simulations of the industrial equipment. The model created was validated based on specific experimental campaign.

Problems of this thesis presents a comparison of selected chippers available in the Republic, describing the structural design of wood chippers, subsequent evaluation of selected machinery energy consumption and quality of the final product depending on the volume of processed wood biomass, then evaluate the economics of machine.

The thesis is focused on designing of backpressure steam turbine to drive the crusher in the sugar factory having the power input of the 2 200 kW. Thermodynamic calculation of two conceptual variations is gradually implemented in the thesis with the aim to determine the steam mass flow through the turbine. In the first version the control stage is selected as an A-wheel and in the second version as a Curtis wheel. The stage part of both versions consists of series action stages. Furthermore, it contains basic design of the gland steam system and the nozzle control system. Both radial and thrust bearings are designed based on the acting forces. The thesis also includes strength calculation of the selected components. The final part deals with comparison and evaluation of the optimal solution. Due to the small difference in rotor weight (m =19,72 kg), and especially for the less steam consumption (M = 4,87 kg/s), the first version can be considered as an optimal solution. This thesis is amended by a mechanical drawing of the turbine cross section on a common frame with a gearbox.

This thesis is focused on designing and manufacturing a shredder for plastic waste 2H for small companies, households and blocks of flats. Thesis contains brief description of plastics, their properties and usage in praxis. It deals with excessive production of plastic, noncircular economy of waste and unsatisfactory processing of plastic waste. There are examples of collecting, sorting and recycling technologies and their application in praxis. It consists of current overview of shredders available on Czech and Slovak market and their comparison. Practical part of this thesis focuses on design itself, its components, parameters and economic issues of manufacturing. Annex contains 3D model of shredder assembly, bought components overview, assembly drawings and photo documentation of created shredder.

This thesis is focused on determination of the power effects, strength calculation and following optimalization of the box for grain roller mill S 1200 – the prototype of the mill to be produced by the copany ROmiLL, s. r. o. Besides issues mentioned above there ar also stated roller mills worldwide trends as well as results and evaluation of the calculations together witu optimalization of roller mill box.