Browsing by Subject "Magnetic separation"

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Comparison of One and Two Stage High Pressure Rolls Grinding followed by Ball Milling with Conventional Rod and Ball Milling
(University of Minnesota Duluth, 1999-07-20) Benner, Blair R
With the development of the autogenous wear surface, the high pressure roller press (HPR) is receiving interest from the mineral industry. Previous work by the Coleraine Laboratory had indicated energy saving using a single stage of HPR compared to rod milling and an energy saving using 2 stage HPR compared to single stage HPR. The purpose of this study was to compare three flowsheets using the same feed and producing a final size of about 85 percent passing 270 mesh. The flowsheets were as follows: (1) Rod mill followed by wet magnetic separation with ball mill grinding of the magnetic concentrate; (2) HPR closed with a 3 mesh screen followed by wet magnetic separation of the screen undersize and ball milling of the magnetic concentrate; (3) HPR closed with a 3 mesh screen with the screen undersize being upgraded by dry magnetic separation followed by open circuit HPR on the magnetic concentrate with wet magnetic separation of the HPR product and ball milling of the wet magnetic concentrate. The test work indicated that the single stage HPR required 27.25 kWh/It of new feed compared to 34.0 kWh/It for the rod mill to produce an 85 percent passing 270 mesh ball mill discharge. The two stage HPR flowsheet was even more energy efficient, requiring only 23.29 kWh/It of new feed. With the single stage HPR, the energy savings appears to be only in the coarse grinding. The ball mill grindability, as measured by the operating work index, was essentially the same for the rod mill and HPR magnetic concentrates. The two stage HPR resulted in energy savings in both the coarse grinding and in the ball milling. The operating work index for the ball mill portion only was 23.5 kWh/It of ball mill feed for the two stage flowsheet compared to about 29 kWh/It for the other two flow sheets. Davis tube tests on the ball mill discharges suggest that there is a liberation benefit associated with the two stage HPR flowsheet, but not with the single stage HPR flowsheet.
Concentrator Modeling Database Development and Simulation of Ispat Inland Plant
(University of Minnesota Duluth, 2003-09-05) Ersayin, Salih
The Ispat Inland plant processes two blends of ore during different time periods throughout the year. Although these two blends have mineralogical differences, they go through the same process. The major difference in the process becomes fineness of grind required to achieve desired level of liberation, which is in tum controlled by the rod mill feed rate. This created a unique opportunity for modeling the effect of mineralogy on separation equipment and measuring reliability of the simulator in predicting perfonnance of non-concentration equipment, such as hydrocyclones and fine screens, under different operating and feed conditions. While performance of concentration devices including magnetic separator, hydroseparator and flotation banks was expected to show dependence on variation in mineralogy, particularly on liberation size, performance of classification and screening devices would be largely independent of the liberation characteristics. Therefore, the models were expected to reasonably simulate the performance of these devices for a given blend when plant data from the other blend was available. On the other hand, performance of grinding mills is mostly governed by the grindability characteristics of a given ore type. Differences in mineralogy may or may not have significant effect on their performance, depending on whether or not change in mineralogy create significant variations in grindability. If such variation occurs, then the question is: how can it be simulated? This study could also provide a guideline for refining grinding models to account for such variations.
Development of a Mathematical Model for Fine Screening
(University of Minnesota Duluth, 2004-04-16) Pletka, Jeremy
Usim Pac mineral processing plant simulation software is used by the University of Minnesota's Coleraine Minerals Research Laboratory Concentrator Modeling Center to simulate taconite plant operations. Its ability to simulate fine screening is limited, since the present suitable models assume a constant partition curve for a given set of screens and do not account for changes in operating conditions. As it is well known that the fine screen unit operation is sensitive to operating conditions such as feed density, loading, and size, it becomes clear that for accurate simulations, the model will require modifications. Consequently, a series of tests was performed on a pilot scale unit where several of the operating conditions were varied. Partition curve parameters were then related to operating conditions for relevant mineral components.
Fitting Of Liberation Model Parameters To Davis Tube Test Data
(University of Minnesota Duluth, 1999-08-19) Wiegel, Ronald L
After 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.
Iron Ore Processing Improvements through Process Modeling and Computer Simulation
(University of Minnesota Duluth, 2001-06-15) Ersayin, Salih
In 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.
Iron Ore Processing Improvements through Process Modeling and Computer Simulation - 2003
(University of Minnesota Duluth, 2003-09-05) Ersayin, Salih
When 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.
Magnetic Taconite Concentration Modeling
(University of Minnesota Duluth, 1999-07-29) Wiegel, Ronald L
A 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.
Potential Value Added Products from the Minnesota Ilmenite Deposits
(University of Minnesota Duluth, 2002-10) Benner, Blair R; Niles, Harlan B
As part of the University of Minnesota’s ongoing support for the development of ilmenite deposits located within the Duluth complex, the University’s Permanent Trust Fund sponsored a project by the Coleraine Minerals Research Laboratory to determine if valued added products could be produced from the ilmenite deposits and to determine if ilmenite recovery could be increased. A previous study sponsored by the Minerals Coordinating Committee indicated that using high pressure rolls in place of a rod mill to grind the ilmenite increases TiO2 recovery by about 10 percent. The major loss of TiO2 (about 25 %) was associated with the removal of magnetite by magnetic separation after spiral concentration. The objective of this program was to determine if the magnetic portion of the spiral concentrate could be upgraded to make a concentrate suitable for either blast furnace pellet feed or DRI feed. During upgrading of the magnetic portion, non-magnetic materials should contain the bulk of the ilmenite, and they would also be upgraded to determine the potential for additional ilmenite recovery. Initial liberation grinds and Davis tube tests on the spiral magnetic concentrate indicated that grinding and magnetic separation alone could not upgrade the material sufficiently. Standard silica flotation on the ground and magnetically separated material did not provide significant upgrading. The best concentrate produced contained 58.84 percent iron, 6.66 percent TiO2, and 5.74 percent silica. Perhaps this material could be used in the iron nugget process. Amine flotation, fatty acid flotation and WHIMS were used to recover TiO2 from the non-magnetic portion of the reground spiral magnetic concentrate. Only fatty acid flotation of the ilmenite showed any potential for recovering additional ilmenite at grade. Additional test work on the use of silicate depressants is needed. Elutriation tests on size fractions indicated that grinding to finer than 200 mesh is needed for liberation of the ilmenite from the silicate gangue. While the previous test work showed increased TiO2 recovery in the spiral nonmagnetic fraction, no work was conducted on upgrading that material to determine if the increased recovery could be carried through to a final concentrate. Therefore, bench scale electrostatic separator tests were run on the spiral non-magnetic fraction produced in the previous project. The electrostatic tests indicated that both grade and recovery could be obtained.
Taconite Concentrator Modeling ‐ 2005
(University of Minnesota Duluth, 2005) Ersayin, Salih
Taconite Process Water and Tailing Water Quality Cationic-Exchange Effect on Balling and Flotation: Final Report
(University of Minnesota Duluth, 1999-10) Engesser, John
A research project supported by the Minnesota Department of Natural Resources and the Iron Ore Cooperative Research Committee was undertaken to 1) evaluate the problems related to cation exchange mechanisms that occur during wet grinding, flotation and balling and 2) investigate ionic formation and precipitation that occurs in the processwater during taconite processing. The cation exchange capacities of rod mill feed samples from two taconite plants were determined. Ball mill grinding, magnetic separation, bench scale flotation and balling tests were performed to establish the effect that cation exchange has on flotation and balling. Tests indicate that balling and flotation are affected by the cation exchange capacity of processed taconite ore. The rate of formation of sulfate, fluoride and bicarbonate anions during the grinding of taconite rod-mill-feed was determined. Sulfide oxidation to sulfuric acid followed by neutralization with carbonate minerals was studied. Fluoride liberation from the taconite ore was also investigated.

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