NC0000400_Request for Special Order by Consent 1987_19870414

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WATER 4U, L1TY
SECTION
April 14, 1987
Mr. Mike Parker
State of North Carolina
Department of Natural Resources
and Community Development
59 Woodfin Place
P.O. Box 370
Asheville, NC 28802
SUBJECT: Request for Special Order by Consent
NPDES Permit No. NC0000400
Dear Mike:
As a response to our meeting on March 20, 1987, and your letter on
April 2, 1987, I have been in touch with our corporate engineering
staff and would like to submit the following program.
First, as you know, Indusmin' s present system can be described
as below.
(1) All the water that leaves the wet processing building has
been treated with lime.
(2) The process water in the treatment ponds was recirculated
to the rodmill area but not the flotation.
(3) The fluoride bearing water from the drain bins is being
recirculated to the front end of the feldspar float cells.
Recently, the plant has improved the recycle system from the drain
bins. This was done by placing PVC pipe in the area that previously
was an open, run-down trough system. By doing this, we increased the
amount of fluoride bearing water that we recirculated. Because of
this action two noticeable events occurred. We no longer use fresh
water in the feldspar float stage and the total lbs/day of fluoride
in the effluent has decreased to 140 - 170 lbs/day range.
The areas for improvement are in the pH control and the amount
of water that is recirculated. Therefore; the plan is as follows.
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Mr. Mike Parker Page 2
April 14, 1987
(1) Calcium fluoride precipitation method that is presently
utilized can be improved with a pH control system utilizing
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a bulk bin with a live bottom bin discharge, accurate volume
metric feeder and a pH control system. The ppm of Fl can
be controlled at 25 or less.
(2) The present plant water discharge is approximately 0.75 MGD.
If we utilize the water tank on the top of the hill , which
has 40,000 gallon capacity, to act as a head tank and supply
recycled water at a constant pressure to the wet processing
building, we can use recycle water in the two areas that we
are not currently utilizing; the mica float and the garnet
float.
(3) The third and last phase would be to separate the quartz
tailing from the fluoride bearing water and process the
fluoride water by ion exchange or activated alumina. This,
however; will not be attempted until the results of steps
(#1) and (#2) are completed. If the results of step one
and two are successful , step three will be employed in the
future when the pounds per day of Fl of the plant effluent
is further reduced.
The feasibility calculations on steps (1) and (2) are as follows:
ASSUMPTIONS
.l. (a) with pH control - Fl ppm = 25
(b) the present water discharge rate to North Toe River - 0.75 MGD
with increased recycle to float it will become a 0.46 MGD
(c) Therefore
25 ppm X 0.46 MGD X 8.34 = 96 lbs/day of Fl .
The cost of the project is estimated beim. :
pH Control
30 Ton Bin 10' dia. X 28' ht.
installed $30,000
Live bottom bin 7 ,000
Volume feed screw 5,000
12' X 12' polymer shed 2,000
pH control 4,000
Electrical & Misc. 2,000
50,000
Water System
8" 80 schedule PVC pipe
$5.00/ft & 1000' 5,000
Couplings & valves 3,000
Installation 5,000
$13,000
Contincency ( 10°/;.) 6,300
TOTAL PROJECT $69,300
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Mr. Mike Parker Page 3 -April 14, 1987
With this correspondence, I hope it will suffice for the plans
and specifications of our water handling system. Indusmin will have
issued purchase orders for all equipment by May 29, 1987. All equipment
should be on site by August 1, 1987. Construction will begin on or
before August 14, 1987. Construction will be completed by September 30,
1987. Indusmin's facility will comply with the final effluent limitations
• on or before October 16, 1987.
I hope the above information will help you in processing the SOC.
Sincerely,
INDUSMIN INCORPORATED
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Robert M. Carland
Technical Manager
RMC/sch
cc: Ben Robinson
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