This Report of Investigations (RI) is one of several describing work that has been completed by the U.S. Bureau of Mines at the Midnite uranium mine, Wellpinit, WA. Dean (in preparation) describes the entire project history. Four diskettes containing three archives compressed using WINZIP (or PKZIP) accompany the current RI. The ultimate purpose of this research effort was to develop a groundwater flow model (GWFM) for the Midnite Mine that can be utilized by the contractor preparing the Environmental Impact Statement (EIS) and by other interested parties. The objectives of this study were to (1) develop a shell model of the geology at the site, (2) develop the basis for a GWFM that will meet criteria described elsewhere in this RI and that can be updated with new information generated during the EIS process, and (3) present the results of two steady-state simulations of groundwater flow within the bedrock units. The current GWFM generates nonunique solutions because flow data for the bedrock units currently do not exist. However, the model provides useful results with respect to direction of flow. More data are required to model the bedrock aquifer system accurately. Volmnetric flow rates of the bedrock units should be measured …

The Midni'e Mine is an inactive, hard-rock uranium mine in Stevens County, WA. Oxidation of sulfide-containing minerals in the ore body produces large quantities of acidic water. The U.S. Bureau of Mines was directed by Congress in Fiscal Year 1994 to perform technological research on the treatment of radioactive water and disposal of treatment residues at the Midnite Mine and en overall site reclamation. This Report of Investigations summarizes the studies that were completed on: 1) treatment alternatives for uranium contaminated acid mine drainage, and 2) overall site reclamation, including: ground water flowpaths in the bedrock, radiation, and waste rock reactivity. As an aid to site reclamation, a Geographic Information System database was also produced that contains available current and historic data and information on the Midnite Mine. This report explains the scope of the Bureau's study and summarizes the results of its investigations.

From abstract: This U.S. Bureau of Mines (USBM) research simplified an earlier hydrogen chloride (HCl) leachsparge process developed by the USBM to recover reduction-grade alumina from domestic kaolin clay. Improvements were made by decreasing the initial leaching acid concentration from 25 to 20 pct, decreasing the leaching time from 1 to 2 h to 15 to 30 min, eliminating the solvent extraction step for Fe removal, and eliminating the step to recover the Al content of the bleedstream circuit. A 10-cycle bench-scale experiment of the simplified process showed that the ferric chloride (FeC 3) concentration built up to 9.3 g/L in the recycle stream. This did not interfere with any of the unit operations or final alumina product purity because Fe forms stable soluble chloride complexes when sparged with HC and is easily washed from the large aluminum chloride hexahydrate (ACH) crystals. The reduced leaching time and acid concentration did not decrease Al extraction.

Abstract: A geographic information system (GIS) database has been developed by the U.S. Bureau of Mines (USBM) for the Midnite Mine and surroundings in northeastern Washington State (Stevens County) on the Spokane Indian Reservation. The mine is an open pit uranium mine which has been inactive since 1981. The GIS database was compiled to serve as a repository and source of historical and research information on the mine site. The database supported USBM hydrological and reclamation research on the mine site. The database also will be used by the Bureau of Land Management and the Bureau of Indian Affairs (as well as others) for environmental assessment and reclamation planning for future remediation and reclamation of the site. This report describes the data in the GIS database and their characteristics. The report also discusses known backgrounds on the data sets and any special considerations encountered by the USBM in developing the database. Most of the database also is planned to be available to the public as a two-CD-ROM set, although separately from this report.