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` Page 5 ~ • <br />Dr. James A. Pendleton <br />July 31, 1992 <br />DH-13 <br />BMR assumes MLRD is referring to the BMR response identified as <br />"DH Comment #13", set forth on page 9 of BMR's letter dated <br />July 13, 1992. Given this assumption, BMR concurs with MLRD's <br />interpretation. <br />DH-22 <br />BMR concurs with MLRD's interpretation. <br />DH-23 <br />The system is designed with 60$ more cyanide destruction <br />capacity than required for typical operating conditions. With <br />minor change in operating techniques (primarily dilution with <br />make up water to reduce slurry density), additional capacity <br />above the 60$ can be achieved for short periods. Therefore, <br />BMR believes there is adequate conservatism incorporated into <br />the design limit of the Inco unit. Of course, if the input <br />limit is exceeded and cannot be controlled to ensure the <br />desired treatment efficiency, then the cyanide feed would be <br />stopped pending attainment of the design feed limit. <br />Safeguards include sensing probes which cause a system alarm if <br />normal operating limits are exceeded. (See Technical Revision <br />No. 010 Page 6.) <br />RESPONSE TO MLRD'8 ANALYSIB OF DAVID HYATT'8 COMM~ENTB <br />DATED JULY 15, 1992 <br />G-2 <br />See BMR's response to paragraph 1 above. <br />5-1-1 <br />The only reason that copper sulfate would be require other than <br />for rectification of the occasional process upset would be for <br />the possibility the ore copper content would be significantly <br />less than at present or significantly less than has been shown <br />in recently completed mine modeling studies. The studies were <br />based on assay data from drilled holes through the ore zones. <br />If the amount of copper should fall below the amount required <br />for catalization of the Inco system, it will be necessary to <br />add copper as copper sulfate to the reactor. Copper levels in <br />the ore and tailings slurries have historically and consistent- <br />ly been well above the levels required for the desired reac- <br />tions. Inco test work indicates that the reactive Fe content <br />of the ore is far below levels which could adversely affect the <br />Inco treatment process. <br />