[Federal Register Volume 59, Number 164 (Thursday, August 25, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-20858]


[[Page Unknown]]

[Federal Register: August 25, 1994]


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DEPARTMENT OF THE INTERIOR
Bureau of Mines

 

Santa Cruz In Situ Copper Mining Research Project; Draft 
Environmental Assessment; Public Meeting

AGENCY: Bureau of Mines, Interior.

ACTION: Notice of availability of draft environmental assessment (EA) 
prepared for the Santa Cruz In Situ Copper Mining Research Project and 
notice of public meeting.

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SUMMARY: In accordance with section 102 (2) (C) of the National 
Environmental Policy Act (NEPA), a draft EA has been prepared for the 
Santa Cruz In Situ Copper Mining Research Project and is currently 
available for public review and comment. The proposed action is the in 
situ mining of copper from a copper oxide zone using a pattern of 
injection and recovery test wells, and fabrication and operation of a 
pilot-scale solvent extraction-electrowinning (SX-EW) facility to 
remove dissolved copper from solution. The project site is located 
approximately 7 miles west of the city of Casa Grande, Arizona. A 
public meeting to receive comments on the draft EA is scheduled. 
Individual copies of the draft EA may be requested directly from the 
Bureau or viewed at the Casa Grande city library.

DATES: The public meeting will be held on September 14, 1994, beginning 
at 7 p.m. MST. The meeting room will be open at 6:30 p.m. for review of 
displays and informal discussions with project personnel. Comments on 
the draft EA must be received no later than September 26, 1994.

ADDRESSES: The public meeting will be held at the Holiday Inn, 777 
North Pinal Avenue, Casa Grande, AZ.
    Comments on the draft EA should be sent to: Daniel J. Millenacker, 
U.S. Bureau of Mines, Twin Cities Research Center, 5629 Minnehaha 
Avenue South, Minneapolis, Minnesota 55417-3099.

FOR FURTHER INFORMATION CONTACT: For information or to obtain a copy of 
the draft EA, contact Daniel J. Millenacker at the address identified 
above or by phone at (612) 725-4588.

SUPPLEMENTARY INFORMATION: In situ copper mining involves the injection 
of a dilute sulfuric acid solution through a well or wells completed 
into an otherwise undisturbed ore zone; selective dissolution of copper 
as the solution moves through and contacts copper oxide mineralization 
located along natural fractures; collection of copper-bearing solution 
by recovery wells; removal of the dissolved copper from collected 
solution using a conventional SX-EW plant located on the surface; 
rejuvenation of solution to its original strength; and solution 
reinjection back into the ore zone to repeat the cycle. The project 
well field will consist of one injection test well in the center of a 
square measuring 127 ft to a side, and a recovery test well located at 
each of the four corners of the square. This arrangement is referred to 
as a ``five-spot'' well pattern. Injection of solution will occur at a 
rate of about 10 to 50 gal/min. The total area to be occupied by the 
various components of the project (including injection and recovery 
test wells, ground water monitor wells, and SX-EW facility) is 8 1/2-
acres.
    The research project is a cooperative effort of the Bureau of Mines 
and the Santa Cruz Joint Venture (a joint venture formed between ASARCO 
Santa Cruz, Inc., and Freeport Copper Company). The goal of the 
research project is to determine the technical, economic, and 
environmental feasibility of in situ mining of copper oxide minerals. 
The research plan calls for in situ mining to continue until sufficient 
data are collected to evaluate the mining technique. This time period 
is presently estimated to require 18 months to complete, but it may 
extend for up to 4 years. In addition to an environmental review 
performed under NEPA, this project is subject to Federal, State, and 
local environmental permitting requirements.

    Dated: August 18, 1994.
Lewis V. Wade,
Research Director, Twin Cities Research Center.
[FR Doc. 94-20858 Filed 8-24-94; 8:45 am]
BILLING CODE 4310-53-P