André Carlos Silva

Circulating load calculation in grinding circuits

A problem for solving mass balances in mineral processing plants is the calculation of circulating load in closed circuits. A family of possible methods for the resolution of these calculations is the iterative method, consisting of a finite loop where in each iteration the initial solution is refined in order to approach the exact solution. The present work presents a low-complexity iterative algorithm for circulating load calculation in mineral processing closed circuits, thus enabling the construction of reliable mass, metallurgical and water balances. The proposed equations on the algorithm were obtained through the analysis of many industrial systems, taking into account the process operational parameters. A validation was performed with real industrial data, in order to ensure a greater reliability of the obtained results. Two different types of closed circuits are presented, each one with different levels of complexity, to clarify the proposed algorithm. With the results, it is possible to affirm that the proposed iterative algorithm can be successfully applied to any kind of closed circuit in mineral processing. The results were satisfactory with respect to processing speed, convergence of the solution and the number of iterations required for the circulating load calculation.

Mineral paste production from phosphate rock tailings

The dewatering stage is among the most important industrial unit operations, and is widely adopted in many different industries. Nowadays, mineral processing tailings disposal is a big problem due to the environmental degradation it causes. The phosphate rock processing in Anglo American Phosphate Brazil, situated in Catalao/ Go/Brazil, generates around 180 t/h of tailings for a plant feed of 480 t/h (approximately 37.5% of the processing plant feed), with 5 to 10% of solids and approximately 14% of P2O5. Nowadays, the tailings are sent directly to the tailings dam. The present work proposes paste production using the tailings from the phosphate rock processing plant. Through decantation of a tailings sample, a clarified liquid was obtained and drained. The decanted pulp then went through a second stage consisting of vacuum filtration. Flocculant addition in this stage generated a faster sedimentation rate and a higher dewatering performance in next stage of dewatering, because the flocculated material was retained by the filter medium instead of passing through it. The results were satisfactory for paste tailings production with a solid percentage of around 65%.

Temperature Influence in Cornstarch Gelatinization for Froth Flotation

Starches are widely used as depressant in froth flotation operations in Brazil due to their efficiency, increasing the selectivity in the inverse flotation of quartz depressing iron ore. Starches market have been growing and improving in recent years, leading to better products attending the requirements of mineral industry. The major source of starch used for iron ore is the cornstarch, which need to be gelatinized, by heat or sodium hydroxide (NaOH) addition, prior its use. This stage has a direct impact on industrials costs, once the lowest consumption of NaOH in gelatinization provides better control of the pH in the froth flotation and reduce the amount of electrolytes present in the pulp. In order to evaluate the influence if the temperature in the NaOH consumption gelatinization tests were carried out with temperatures ranging from 25 to 65 ° C, measuring the volume of NaOH. All tests were performed in triplicate. A linear model correlating the temperature and the NaOH need for the cornstarch gelatinization had been stablished. This model can allow mineral industries to optimize the NaOH amount used to prepare the depressant to be used in froth flotation. For example, the reduction in NaOH could easily reaches 480 L per ton of cornstarch when performing gelatinization with cornstarch solution at 35 ° C when compared to 25 ° C.

Microflotação de Apatita com Óleos da Polpa e da Castanha de Macaúba

The apatite is the main source of phosphate used as input in the manufacture of industrial fertilizers, so studies that seek alternatives to the best use of this ore is very important in an essentially agricultural country like Brazil. During its processing, the fatty acids act as collector agent in the flotation step thus becomes essential to search for reagent system that would improve efficiency in this process. In this sense, the macaúba (Acrocomia aculeata) is a fruit that arouses interest for present high concentrations of fatty acids. The differences in fatty acid composition suggest different behavior when used as collectors in the flotation of minerals. the present study sought to demonstrate, through microflotation testing Hallimond tube, the potential use of macaúba oils in the flotation of apatite. The tests were performed with 1.0 g of high purity apatite, with a particle size of 104μm at pH 8, 9 e 10 varying concentrations of the collector at 2.5, 5.0, 7.5 and 10.0 mg/L. The results showed a better floatability at all concentrations tested for pulp oil compared with macaúba’s nut oil.

Aproveitamento do Rejeito da Mineração de Calcário Utilizando a Briquetagem como Processo de Aglomeração

Technological application in agriculture within the production system is globalized reality. Liming is a cheap practice, but is neglected as to its use. Briquetting is the agglomeration of fine particles by pressure, with or without a binder, allowing obtaining compacts, the shape, size, and adequate mechanical parameters. The recent environmental concern, resulting in stricter laws, and the need to economically harness waste and fine particles generated in ore processing caused briquetting back be an important alternative for forming economic value. The objective was to agglomerate fine limestone generated in the same processing by briquetting, varying amounts of water (used as a binding agent) 0; 5; 7.5; 10; 12.5 and 15%. The briquettes were subjected to drop tests at 30, 60, 90, 120 and 150 cm. Best results found for resistance were obtained with 7.5% moisture, with averages of 21 falls to 30 cm and 10 falls to 60 cm. These results were favorable when compared to the literature, which mentions that for briquettes no cure, it is considered 3 falls to 0.3 m as a reasonable value. Result is seven times higher than the minimum required.

Flotação de Apatita Utilizando Óleo de Pinhão-manso

Agradecimentos: Às agências de fomento CNPq, CAPES e FAPEG pelo auxílio financeiro, primordial para a realização do presente estudo, bem como à Embrapa Agroenergia e à Claraint por ceder amostras utilizadas no estudo e à Universidade Federal de Goiás. Resumo: As reservas brasileiras de rochas fosfáticas estão concentradas em maioria nos estados de Minas Gerais e Goiás, onde também está concentrada

Hydrocyclones simulation using a new modification in Plitt's equation

Abstract Hydrocyclones are devices worldwide used in mineral processing and used for desliming, classification, selective classification, thickening and pre-concentration. Versatile in application, the hydrocyclone is the standard classifier used in closed circuit milling in mineral processing plants. A hydrocyclone is composed by a cylindrical and a conical section joint together, without any moving parts and it is capable of perform granular material separation in pulp. The pulp is feed under pressure tangentially to the cylindrical section. The granular separation mechanism is complex and its mathematical modelling is empirical. The most used model for hydrocyclone dimensioning was proposed by Plitt (1976). Combining the first industrial database on cyclones generated at JKMRC with his own laboratory data, Plitt developed an alternative general- purpose cyclone model. Over the years many revisions and corrections to Plitts model were proposed. The present paper shows a modification in the Plitts model constant, obtained by exponential regression of simulated data for three different hydrocyclones geometries (Rietema, Bradley and Krebs). The proposed model validation used literature data obtained from phosphate ore using fifteen different hydrocyclones geometries. The proposed model shows a correlation equals to 88.2% between experimental and calculated corrected cut size, while the correlation obtained using Plitts model was 11.5%

Circulating load calculation in mineral processing closed circuit operations

Abstract A problem for solving mass balances in mineral processing plants is the calculation of circulating load in closed circuits. A family of possible methods to the resolution of this calculation is the iterative methods, consisting of a finite loop where each iteration the initial solution is refined in order to move closer to the exact solution. The present work shows a low-complexity iterative algorithm for circulating load calculation in mineral processing closed circuits, thus enabling the construction of mass, metallurgist and water reliable balances. The proposed equations on the algorithm were obtained through the analysis of many industrial systems, taking into account the process operational parameters. A validation was performed with real industrial data, in order to ensure a greater reliability of the obtained results. Four different types of closed circuits are presented, each one with different levels of complexity, to clarify the proposed algorithm. With the obtained results it is possible to affirm that the proposed iterative algorithm can be successfully applied to any kind of closed circuit in mineral processing. The results obtained were satisfactory with respect to processing speed, convergence of the solution and the number of iterations required for the circulating load calculation.

Simulation of the mineral breakage using a fractal approach

Hukkis law is an empirical law, which does not take into account several events of energy loss during the mineral fragmentation processes. Since experimental results are very difficult to obtain for a large range of fragment sizes, the verification of the law is very difficult. The relation between the fracture and fragmentation processes with fractal geometry has been proposed some decades ago. Empirical laws along this context show basic features of fractal geometry, mainly self-affinity and the power law behavior. Thus, in this paper, a model to simulate the fragmentation process and to check the relationship between energy consumption and fragment sizes was developed. The model is represented on a regular lattice where links represent pathways for fracture processes. The energy of fragmentation events was modeled by a probability distribution function. In the proposed model there is no mass loss and the fracture propagation occurs as self-avoiding random walks on the regular lattice.