Browsing by Subject "Mineral liberation"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
Item Development of an Approach to the Simulation of Size Reduction/Mineral Liberation for Magnetic Taconite Ore in Tumbling Mills and Its Implementation in a BASIC Computer Program(University of Minnesota Duluth, 2000-10-13) Wiegel, Ronald LIn late '98, the Iron Ore Cooperative Research Committee decided to fund a math modeling/simulation center for magnetic taconite concentrator applications at the Coleraine Minerals Research Laboratory of the University of Minnesota. In a previous association with the iron ore industry, the writer was actively involved in early attempts at modeling and simulating the magnetic taconite beneficiation process. After returning to the University of Minnesota and the iron ore industry in 1997, I attempted to play "catch up" on developments over the past twenty years related to magnetic taconite process modeling and simulation. Based on that review, it was evident that two items that are of particular importance for magnetic taconite process simulation were still missing from the tools available in the software packages for mineral process modeling/simulation. These are: (1) a suitable technique for handling the description of mineral liberation as a function of changes in particle size resulting from size reduction steps in the process and (2) the prediction of the performance of rotating drum magnetic separators as a function of their design and their operating conditions. It was therefore decided that steps should be taken to begin to address these deficiencies very early in the life of the Taconite Concentrator Modeling Center. The more complex of these two problem areas is the development of a technique for describing how mineral liberation, and the resultant possible early rejection of minerals to waste, can be related to particle size changes resulting from crushin~ and grinding size reduction. There have been numerous approaches to this subject, 10 • 1 but none have taken it to a useful conclusion. Lacking a model of the simultaneous mineral liberation/size reduction operation, some investigators have resorted to the assumption of complete mineral liberation, that is, all mineral species are totally free of other mineral species. This is certainly not appropriate for magnetic taconite, where rejection is dependent on grinding. The approach reported here begins with an early conceptual model of a binary mineral system's liberation by size reduction, as described by A. M. Gaudin in his 1939 text "Principles of Mineral Dressing." Relationships have previously been obtained to describe the amount of liberation of either component and the quantity/composition of unliberated or "locked" middlings as a function of the "effective" mineral grain size, particle size and the original ore's volumetric composition. The new developments described in this report make use of mathematically derived "directional coefficients" to follow the gradual transfer of material from locked assemblages of dissimilar mineral grains of one composition to other locked particle compositions and eventually to liberated particles of value or waste, as particle size is reduced. Finally, a BASIC program has been developed and is presented, which permits one to calculate the simultaneous liberation/size reduction phenomena for multi-stage, perfectly mixed, tumbling mills in series. The liberation parameters of a particular crude magnetic taconite ore sample are obtained by collecting Davis tube data for individual particle size fractions and subjecting these to a "best fit" program described in an earlier report. Once the liberation parameters are defined, appropriate breakage rates of the liberated and locked middling particles can be used in combination with the geometric effects of the resultant size reduction on mineral liberation to simulate in a relatively simple and understandable way the complex operation of size reduction/liberation. This BASIC program must now be translated into an appropriate FORTRAN program for use with the BRGM USIMPAC mineral processing simulation software. It can then be used in concert with other models to simulate the entire magnetic taconite beneficiation process.Item Fitting Of Liberation Model Parameters To Davis Tube Test Data(University of Minnesota Duluth, 1999-08-19) Wiegel, Ronald LAfter studying the direction work in mineral liberation has taken for the past twenty years, and in particular the more recent five to ten years, it has become apparent to me that at least for the magnetic taconite process, the use of the Davis tube ideal magnetic separator on individual size fractions of process feed can provide useful data on liberation. A study made by the writer1 of process feed samples to twelve magnetite concentrators indicated a reasonable conformity between Davis tube concentrate magnetite grade and size fraction mean particle size relationships and what was predicted using the idealized "random liberation model" formulation2 with appropriate specific gravities for magnetite and waste minerals. This then suggests that the magnetic taconite liberation behavior can be characterized by three parameters (given the two specific gravities): (1) magnetite ore feed grade; (2) an average mineral grain size; and (3) an average size fraction particle size. Of the twelve sample sets noted above, only two indicated significant deviations from the shape of the concentrate grade-particle size relationships displayed by the "random model." A BASIC computer program (LIBFIT.BAS) has therefore been written to obtain the best fit of the two parameters: magnetite feed grade of the ore and average mineral grain size for the "random model," to Davis tube data on size fractions of ground taconite. The program is relatively simple in concept, in that it first seeks a value of average mineral grain size, which minimizes the sum of squares of differences in the measured and calculated Davis tube concentrate grades for an estimated magnetite feed grade of the ore. It then holds the optimum average mineral grain size constant and searches for the optimum magnetite feed grade for that mineral grain size. It continues to switch back and forth, looking at first mineral grain size and then magnetite ore feed grade for some 18 iterations, which then provides a best fit estimate of the two parameters.Item Iron Ore Processing Improvements through Process Modeling and Computer Simulation(University of Minnesota Duluth, 2001-06-15) Ersayin, SalihIn 1997, under the auspices of the Iron Ore Cooperative Research Program, iron ore mining companies operating on the Iron Range decided to work as a consortium in establishing expertise in the development of math models of individual taconite concentration operations and their use to simulate portions of the integrated concentration process. This led to the establishment in 1998 of the Concentrator Modeling Center within the Coleraine Minerals Research Laboratory (CMRL) of the University of Minnesota - Duluth. Following discussions on the type of software to be used by the Center, Usim Pac, mineral processing software developed by BRGM of France was selected due to the availability of a larger number of models, and model incorporation capability to add those to be developed in the future. The Center became fully operational when Dr. Salih Ersayin started to work as the program director on Nov. 1, 1999. While the application of modeling and simulation has provided significant benefits in the processing of base metal ores, its application to the processing of magnetic taconite has been hindered. This was caused by the need to incorporate the modeling of mineral liberation into the comminution models for size reduction steps, which occur between several stages of magnetic separation. An initial effort at integrating the modeling of size reduction, mineral liberation was carried out by Wiegel1 for the Erie Mining Company process in 1976. Plant scale implementation of the combined use process modeling and plant testing was reported for the National Steel Company secondary grinding section modifications 2 . Recently, Schneider 3 developed a mineral liberation model based on liberation characterization by scanning electron microscopy measurements. He validated his model using plant data obtained from the Fairlane Plant of Eveleth Taconite. For simulation purposes, he integrated his liberation approach into a ball mill grinding model. He also presented magnetic separator and hydrocyclone model structures compatible with the type of data produced by the liberation model. Despite of these developments, there still was a need to develop a simplified approach to the integrated size reduction/liberation model for taconite processing, models for magnetic separators, hydroseparators and fine screens, which would take into account the significant operating and design parameters. Therefore, the initial efforts of the Center were concentrated on development of simplified integrated mineral liberation/size reduction and magnetic separator models using funds allocated by the Permanent University Trust Fund (PUF), while providing a simulation service to taconite plant operators with the available software. Data from four plants in the Range taken as a part of an earlier Iron Ore Coop project was analyzed using the existing capabilities of the software. The data was first mass balanced and performance of individual pieces of equipment was examined. Results were presented to the plant engineers; their implications and potential improvements were discussed. To illustrate the capabilities of the software and potential benefits from the use of simulation, some modifications in plant flow sheets and operating/design conditions were simulated using the same data as a basis. These simulation results were also presented to the relevant engineers.Item Iron Ore Processing Improvements through Process Modeling and Computer Simulation - 2003(University of Minnesota Duluth, 2003-09-05) Ersayin, SalihWhen the Concentrator Modeling Center was established in 1998, its first task was to define the prevailing conditions in terms of taconite plant simulation. Capabilities of existing software and unit operations needing improved models were defined. Preliminary simulations were carried out to determine how accurately the existing models could simulate taconite plant operations. Plant data was analyzed to determine how taconite plant operation could be simulated and to define the common problems and bottlenecks. It also provided some insight in terms of model development. This work indicated that there was a need for improved model development for the unit operations commonly used in taconite processing. Therefore, the Center's task was defined as "to develop advanced models, while providing simulation based assistance to the taconite plant operators using available simulation capabilities. n On the model development side, the specific objective was to develop improved models for magnetic separators, hydroseparators, fine screens and mineral liberation. Despite unsuccessful attempts to obtain federal funding for this type of work due to unwillingness of federal sources to fund projects that would benefit only a smaller section of the mining industry, the Center managed to improve the very simple models available for these unit operations using its plant database and limited funding for specific projects, Now it has the capability of simulating taconite processing more realistically. This was achieved . by analyzing available plant data and developing theoretical understanding of how these unit operations function, and along with pilot scale testing in the case of fine screen modeling. The Center's task was not only to develop these models, but also to incorporate them into the existing software, Usim Pac. Models for magnetic separators and hydroseparators were converted to the programming language of the software. The liberation model is expected to be incorporated soon. The Center's simulation efforts were concentrated on case studies involving the Evtac and lspat Inland plants. While replacing hydrocyclones in a ball mill grinding circuit with fine screens was the focus of study in the former plant, improving overall plant performance was the aim in the latter, which is still an on-going project funded by the DOE. Another simulation study was carried out to determine benefits of ore segregation in one of the taconite plants.Item Magnetic Taconite Concentration Modeling(University of Minnesota Duluth, 1999-07-29) Wiegel, Ronald LA greatly simplified predictive liberation model has been used to generate information about the expected quantity and composition of locked middling particles, dependent on mineral grain size, particle size, ore head grade, and mineral specific gravities. This information has then been calculated for mineral systems with head grades in the range of magnetic taconite crude ore. One special "infinite dilution" case has also been evaluated which might find use with low head grade deposits such as copper and nickel sulfides. The current plan is to use these tables and relationships in developing a new and different approach to the modeling of magnetic taconite size reduction-mineral liberation.