1989-11-22_REVISION - M1988112

• Permit No: M1988112
• IBM Index Class Name: Revision
• Doc Date: 11/22/1989
• Doc Name: TAILINGS COLUMN TESTING PROCEDURES BATTLE MTNS SAN LUIS PROJECT
• Type & Sequence: AM1
• Media Type: D
• Archive: No

O
U
0
O
0
E
1,2%S
~ NP
r
H _ / \
~ / \/
U
< / ,

TIME (wt,~ktt)
Figure 4. Plot of leachate acidity and
sulfate rnncentra lions versus time for
sample 9.
0
D
E
system. Nere again, the acid (A) is being
neutralized, but significantly minor amounts
of acid begin to appear in the 'a' leachate
after about the fifth week. Minor increases
in the sulfate (i.e., the sulfate content
of the leachate exceeds the sulfate content
of the leachate A) suggest that the NP has
been removed from some pyrite sites, but a
large amount is still present to neutralize
the acidity introduced.
Sample No. 9 had a low NP (4) but a
moderate sulfur content (1.2 percent). As
evident in Figure 4, the amount of acidity
produced after the third week exceeded the
amount introduced. Hole also hoe the sul-
fate content increased with time, reflect-
ing pyrite oxidation. This is true for
both the deionized eater and the synthe-
sized acid rain. This sample also showed
that deionized water was more reactive than
the acid rain. This sample is considered
to be an acid producer because of the
paucity of calcareous material (low NP) and
the moderate amount of sulfur.
Sample No. 10 had a high acid produc-
tion potential (3.1 percent sulfur) and some
NP (13). It is interesting to note in Fig-
ure S that the sulfate contents of all
leachates during the entire course of the
experiments were significantly high. Yet
during the first six weeks the sample neu-
tralized the acidity that vas introduced to
the system. After this time the amount of
acidity produced exceeded the amount intro-
duced. This vas interpreted as being the
total Consumption of Calcareous material
during the neutralization process. In this
case [hough, the amount of calcareous mate-
rial vas not sufficient to inhibit pyrite
SAMPLE NUMBER I0
i
u
i
O
0
E
r
O
U
uca+o -- •oaa
u~w'+c as ~,a.a' ern
6'~'..,.i u.•• anu
tLL ~ [ O. 4I W.6 r,Y .1 .. lM
~i.~iil~.(ir~.r
8 :~.... .>o.a
O ...no..r won..
•+aa
Kull • lr.
_ an ...~.
7.1 %yS
17 NP ,
i
1
c
a
~._ ,__..
~ / ; ,Cw
TIME (w~~ks)
Figure 5. Plot of leachate acidity and
sulfate concentrations versus time for
sample 10.
oxidation; it simply provided neutralization
of the acidity produced.
Conclusions
This study shoved that the total sulfur
content of a sample by itself is not a good
predictor of acid production potential. At
the same time, it vas found that. the calcar-
eous material present serves in some cases
to inhibit pyrite oxidation, wh i.le in
others, it serves to neutralize the acidity
produced. Samp:es having critical sulfur -
NP values produced acid after being leached
with acid; presumably the removal of the
calcareous material permitted the pyrite to
oxidize.
To assess the probability of a rock to
produce acid leachate requires the con-
sideration of both the total sulfur content
and the amount of calcareous material pre-
sent in the sample. To simply balance the
acid production potential against the neu-
tralization potential to obtain the net
acid-base account does not always yield
reliable results. Consider that the net
acid-base account of sample No. 1 has a net
acid value (-34.6) yet it produced a strong-
ly alkaline leachate.
On a short-term basis the results of
this study have Led Co the formulation of an
analytical technique that combines empirical
data and cold whole rock analyses to obtain
carbonate-sulfur ratios that can loe used to
rapidly and accurately assess a s~~ra[um's
potential to produce acidic leac ha [es
(patent pending).
442