Browsing by Subject "Metal ores"

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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) 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.
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    Required Metallic Exploration, Mining, Processing Permits in Minnesota - The Who, What, Where, and When to Non-Ferrous Metallic Mine Permitting
    (University of Minnesota Duluth, 2002) Severson, Mark J
    In Minnesota, there exists a framework for establishing a new, metallic, non-ferrous mine that involves a process of environmental review and application for various mine-related permits. However, to date, no non-ferrous metallic mines have been developed, and the mine permitting process in Minnesota remains untested. This report is intended to outline each of the permitting steps and to assemble, under one cover, contact numbers and addresses for each of the regulatory agencies that are involved in the process. It is important to stress that this document is intended to serve as only a rudimentary guide in pointing out what types of permits could be anticipated and the minimal length of time (under optimal conditions) that could be required before the mine-related permits are granted. This document is only a “road map” that shows the possible paths for permitting a new metallic mine - it should not be used as a substitute for contacting the various regulatory agencies. The permitting process for a non-ferrous metallic mine in Minnesota involves dealing with several agencies that include: 1) Minnesota Department of Natural Resources (Division of Lands and Minerals, Division of Water, and Office of Budget and Management Services: Review Section); 2) Minnesota Pollution Control Agency (both Air and Water divisions); 3) United States Army Corps of Engineers; 4) local government units; and 5) possibly the United States Forest Service (depending on the location of the mine site). Other agencies that are involved in the process, either directly or indirectly, are also discussed in this report. Although environmental regulations are strong, each of these agencies are willing to work together to help guide mining companies through the environmental review and permitting process to allow for responsible development in an environmentally safe manner. An environmental review, consisting of a Scoping Environmental Assessment Worksheet (EAW) and Scoping Decision, followed by an Environmental Impact Statement (EIS), is mandatory and is one of the first actions that must be completed before any mine-related permits can be granted. There are several background studies, such as waste characterization and other monitoring studies, that will need to be either completed or initiated prior to beginning the environmental review. Concurrent with the environmental review, action will need to be taken on applications for at least eight major permits. Most of these permits will need to be obtained before starting construction of a new mine and auxiliary facilities and include: 1) Permit to Mine (accompanied by a Wetland Replacement Plan); 2) Part 70 Air Quality Operating Permit and NSR Construction Permit; 3) NPDES/SDS Wastewater Permit(s); 4) Section 404 Permit for disturbances to wetlands; 5) Water Appropriation Permit(s); 6) Public Waters Work Permit; 7) Dam Safety Permit; and 8) NPDES/SDS Storm Water Permit for Construction Activity. Action on the first four permits should begin early in the process as some of these permits could take up to 0.5-2.0 years before decisions can be made - decisions on the permits are held in abeyance until a decision is made on the adequacy of the EIS. The purpose of the EIS is to inform the regulatory agencies of possible alternatives that they need to consider when making decisions on whether to grant or deny the mine-related permits. In addition to these permits, another major permit that could be required is a Lease to Mine, obtained from the Bureau of Land Management/United States Forest Service- if the mine site is located on Federal mineral rights. In summary, there are numerous actions that must be initiated and completed before a nonferrous metallic mine can be permitted in Minnesota. These actions include: pre-application background studies, environmental review (scoping EAW and EIS), permit applications, public comment periods, agency comment periods, and finally, decisions on the permits. Under favorable conditions all of these actions could be achieved in 2.5 to 3.0 years. It is up to the proposer to be organized, persistent, professional, and sensitive to public concerns. Each of the regulatory agencies stress that the project proposer contacts them early, hire a competent consultant, and keep them and the public informed of their actions.