محسن آزماینده
13th November 2010, 12:19 PM
Technical Noteلیچینگ اورانیوم
[First application of cyanidation process in Turkish gold mining
and its environmental impacts
A. Akcil
*
Department of Mining Engineering, Mineral Processing Division, Suleyman Demirel University, TR 32260 Isparta, Turkey
Received 16 April 2002;accepted 20 July 2002
Abstract
In the history of Turkey the first use of cyanide for gold recovery has been at the Ovacik GoldMine. During one-year test period,
this mine has successfully been mining and processing after a complicated and extensive environmental impact procedure. In Turkey
about 2500 ton of sodium cyanide are used with about 240 ton of sodium cyanide being used at this mine annually. During the test
period, it has been shown that an effluent quality (CNWAD) between 0.06 ppm (min) and 1 ppm (max) was achievable after cyanide
destruction with the Inco Process. It was also found that treated effluent values (CNWAD) of process water (decant) were between
0.04 ppm (min) and 0.59 ppm (max). This paper presents a review of the cyanidation and cyanide destruction processes at the
Ovacik Gold Mine.
2002 Elsevier Science Ltd. All rights reserved.
Keywords: Cyanidation;Gold ores;Hydrometallurgy;Environmental
1. Introduction
Gold mining and electroplating industries are re-
sponsible for using large amounts of cyanide in their
respective processes. In some cases excess process solu-
tion must be treated to stringent standards and released
into the environment.
The discovery of the cyanidation process developed
from earlier attempts by alchemists to transform base
metals into gold, as well as on the emerging chemistry of
the so-called ‘‘Blue Acid’’ and its compound during the
eighteenth century. The cyanidation process arose from
the discovery that dilute cyanide solutions will dissolve
precious metals from their ores (Habashi, 1987, 1995).
Cyanide combines with and is transformed into many
related compounds. Because of its unique properties,
cyanide is used in the manufacture of metal parts and
numerous common organic products. About 1.4 million
tons of hydrogen cyanide are produced annually world-
wide, of which only about 13% is converted into sodium
cyanide and used in the extraction of gold and silver.
The remaining 87% of the hydrogen cyanide is used in
the production of a wide range of products (Mudder,
2001;Mudder et al., 2001). The allowable potable water
standards for cyanide are 0.2 ppm (United States En-
vironmental Protection Agency), 0.07 ppm (World
Health Organisation), 0.05 ppm (European Union), 0.5
ppm (World Bank) and 1 ppm (Turkish Ministry of
Environment).
Just recently, an international Cyanide Management
Code has been developed by the United Nations Envi-
ronment Programme (UNEP). For this voluntary in-
dustry code, most of participants from gold mining
industry, government, non-governmental organizations,
labor, cyanide producers and financial institutions have
worked cooperatively toward a common goal. The Code
focuses exclusively on the safe management of cyanide
at gold mines. Participation in the Code is voluntary.
Code signatories agree to follow the Codes principles
and to implement its standards of practice. Verification
and certification is accomplished through independent,
third party audits every three years. An operation is
certified when the auditor concludes that the Code is
implemented. A unique symbol may be used by those
operations certified as in compliance with the Code.
Minerals Engineering 15 (2002) 695–699
This article is also available online at:
www.elsevier.com/locate/mineng
*
Tel.: +90-246-2111240;fax: +90-246-2370434.
E-mail address: ata@mmf.sdu.edu.tr (A. Akcil).
0892-6875/02/$ - see front matter 2002 Elsevier Science Ltd. All rights reserved.
PII: S08 9 2-6 8 75 (0 2 )0 01 6 5- 6Operations are de-certified if an audit determines
that the operation is no longer in compliance (UNEP,
2002).
Even if different environmental regulations and codes
are in force in countries where cyanide is primarily used
in mining, cyanide remains an indispensable chemical in
these processes until there is a commercial, economical,
and environmental alternative. This paper presents a
review of the cyanidation and cyanide destruction pro-
cesses at the Ovacik Gold Mine.
2. Ovacik Gold Mine
The Ovacik Gold Mine is located near the western
coast of Turkey (Fig. 1). Although this ore body was
discovered in 1989, the operation finally started to re-
cover gold and silver in June 2001. The open pit shall
produce 200,000 ton/year and the underground mine
100,000 ton/year. The mine exploration programme was
initiated in 1989. Since 1989, a total of 15,000 m of holes
have been drilled in the concession area (Table 1).
In the Ovacik cyanidation plant, ore is first crushed
and then wet ground in mills to liberate gold particles.
Once ground to )38 lm, a high degree of liberation
hence recovery of gold from the ore is achieved.
2.1. Cyanidation process
Approximately 2.5 million tons of cyanide is manu-
factured annually worldwide. Turkey also used ap-
proximately 2500 ton sodium cyanide and this plant is
used 240 ton sodium cyanide annually. In the history of
Turkey, the first use of gold recovery by cyanide was at
the Ovacik Gold Mine. During a test period, ore was
successfully mined and processed after a lengthy envi-
ronmental impact procedure. After the one year test
period, the Ovacik Gold Mine has been waiting a court
decision for continuous operating.
2.2. Cyanide destruction process
As an alternative cyanide destruction process, the
Inco process (sulphur dioxide and air) was patented in
1984 (Borberly et al., 1984). For 18 years, the process
has been successfully applied at scores of gold mines
worldwide. This process is based upon conversion of
CNWAD to cyanate using a mixture of sulphur dioxide
and air with copper sulphate (CuSO4) catalyst. Due to
the need to treated the tailings slurry, the Inco process
was selected the cyanide destruction process in 1994.
The process uses sulphur dioxide, available in a va-
riety of reagent forms, plus air that is dispersed into
solution using a well-agitated vessel. Normally, the SO2/
air process is configured as a single-stage continuous
treatment facility. The technology is safe and reliable
and is selective for total cyanide detoxification. Typi-
cally, the process is capable of removing total cyanide to
less than 2 mg/l, from feeds containing total cyanide in
the range of 50–2000 mg/l (Robbins et al., 2001).
The destruction circuit was designed to destroy 8.4
kg/hr of cyanide in a tailings stream composed of 45–
48% solids (by wt.%). The slurry and cyanide flows have
been calculated using a basis of 900 tones of ore pro-
cessed per day (approximately 180 ppm CNTotal ) (Fig. 2).
Fig. 1. General view of Ovacik Gold Mine, Turkey.
Table 1
Gold potential of Ovacik Gold Mine
Ore reserves Ore (million
ton)
Grade
(g/ton)
Gold content
(ton)
Total (proven–possible–
probable)
4.19 7.6 31.87
Mineable 2.4 10 24
Fig. 2. Process scheme of chemical destruction at Ovacik Gold Mine.
696 A. Akcil / Minerals Engineering 15 (2002) 695–699In many countries there are effluent limits for the
water discharged after chemical treatment prior to being
discharged into the environment. At the Ovacik Gold
Mine there is an effluent limit for discharge of the tail-
ings into the impoundment but none discharge into the
environment. According to test results, the effluent
quality was higher at the Ovacik Gold Mine after treat-
ment than is commonly achieved in USA and Canada,
which are experienced in gold mining and cyanide pro-
cesses (Table 2).
3. Statistical results of process monitoring database
During the test period, ore has been successfully
mined and processed. Process evaluations were per-
formed for a test period of one year (June 2001–May
2002) at Ovacik Gold Mine. Detoxification is defined as
chemically decomposed wastewater discharging into the
tailings pond. Decant is defined as water recycled to the
plant from the tailings pond to use as makeup process
water. Filtered water is collected in drainage pipes at the
bottom from which water is pumped to process water
tank for reuse in the plant.
Daily and monthly results of Detox and Decant are
calculated by using statistical analysis and results of
plant performance as shown on Figs. 3 and 4.
For the Ovacik Gold Mine, the Inco cyanide de-
struction process has a capacity to decompose over 99%
of the cyanide present. The resultant CNTotal concen-
tration in the tailings is lowered to below 1 ppm, which
is the limit of national environment legislations for
CNWAD in the tailings (Akcil, 2001, 2002a,b;Akcil et al.,
2002).
During this period, it has been shown that environ-
mental limits were found between 0.06 ppm (min) and
1 ppm (max) as detoxification discharges (Detox) after
destruction by Inco process. For the process water
(Decant), limits were found between 0.04 ppm (min) and
0.59 ppm (max).
In the light of the statistical data, daily and monthly
cyanide concentrations in the treated effluent at the
Ovacik Gold Mine do not exceed those required by the
Turkish Ministry of Environment (Table 3).
Table 2
Comparision with effluent limits of Ovacik Gold Mine with international standards (Higgs, 1995;US EPA, 1987, 1988;World Bank, 1994)
Element Tailing Turkish
Ministry of
Environment
International Standards
Destruction Discharge Canada World Bank USA
Before After Dama
Environment Dama
Environment Dama
Environment Dama
Environment
CNTotal 144 <1 <1 No discharge 1 No
limit
2No
limit
1No
limit
0.2 CNWAD
Cd <0.01 <0.01 <0.01 1 0.01–0.1 0.1 0.05
Zn 1 <0.1 <0.1 5 0.2–1 1 0.75
Cu 6 0.42 0.42 5 0.05–0.3 0.1 0.15
Pb <0.05 <0.05 <0.05 2 0.05–0.2 0.6 0.3
As 2 0.005 0.005 5 0.01–1 1 –
Sb 10 0.03 0.03 5 – – –
Fe 3 0.129 0.129 10 0.3–1 2 –
Cr <0.01 <0.1 <0.1 2 0.05–0.3 1 –
Hg <0.01 0.007 0.007 0.1 0.001 0.002 0.001
a
No official limits in cyanide discharges into tailings pond.
Fig. 3. Statistical results (max–min) of Detox discharge from June
2001 to May 2002.
Fig. 4. Statistical results (max–min) of Decant discharge from June
2001 to May 2002.
A. Akcil / Minerals Engineering 15 (2002) 695–699 6974. Conclusions
Although cyanide can be toxic to humans and pro-
duce adverse effects on the environment, our knowledge
of cyanide and its related compounds is sufficient to use
it safely. Unfortunately accidents resulting from human
error have and will continue to infrequently occur.
However, the over all safety and environmental record
associated with cyanide is excellent, when compared
with other industrial chemicals. Clearly, the benefits of
cyanide outweigh its risks and over lives would be ad-
versely impacted without it and its products (Mudder,
1999).
The UNEP and the International Council on Metals
and the Environment have carried out and investigated
the accidents occurring in mines and repeated study of
environmental criteria, especially in recent years and in
detail in the last two years. With participation of all
related representative of institutions, the same code
applied to this sector. Volunteer institutions will plan
the application of the Code. The studies done in the
Ovacik Gold Mine successfully tested without exceeding
limiting values of cyanide and heavy metals concentra-
tions during one year (June 2001–May 2002).
Through scientific and engineering investigations
toxic chemicals such as cyanide can be reduced to ac-
ceptable limits or converted to non-toxic forms. For this
reason, the excavation and processing of metals and
minerals from natural sources should be carried out with
regard to environmental concerns. Through studies of
the type conducted at the Ovacik Gold Mine precau-
tions can be taken to provide an appropriate level of
environmental protection and to minimise impacts.
As a result of these studies, the following conclusions
were reached:
• During a test period, environmental criteria were not
exceeded according to the limits of the Turkish Min-
istry of Environment.
• Heavy metal concentrations in Ovacik Gold Mine
wastes are far lower than the limiting values stipu-
lated by European Union regulations for waste slur-
ries permitted to be discharged on to the land.
• A waste discharge to the tailing pond at less than
1 ppm cyanide (CNWAD).
• Recirculation of wastewater from the tailings pond to
the plant could be accomplished.
• Neither direct nor indirect discharge to the receiving
environment occurred.
Acknowledgements
The author wishes to thank the Newmont Australia
Ltd. (former Normandy Mining Co.), Turkey for per-
mission to publish the paper. The author also thanks
Dr. Terry Mudder (USA) for invaluable comments and
for his helpful collaboration. Finally, the author would
like to thank the referees for reviewing this paper.
References
Akcil, A., 2001. Cyanide versus environment: Turkeys final decision.
Mining Environmental Management, UK 9 (6), 22–23.
Akcil, A., 2002a. Turkey, mining annual review. The Mining Journal
Ltd. UK, 1–4.
Akcil, A., 2002b. Cyanide control in tailings pond: Ovacik Gold Mine,
Turkey, in: Seventh International Symposium on Environmental
Issues and Waste Management in Energy and Mineral Production
(SWEMP), Italy.
Akcil, A., Oygur, V., Ciftci, H., 2002. A case study: decomposition of
cyanide and heavy metal stabilization in Ovacik Gold Plant, in:
International Conference on Mineral Processing Technology,
Bangalore, India.
Borberly, G.J., Devuyst, E.A., Ettel, V.A., Mosoiu, M.A., Schitka,
K.J., 1984. Cyanide removal from aqueous streams, Canadian
patent, no. 1,165,474, 10 April 1984;Covered by US patent
4,537,686, 27 August 1985.
Habashi, F., 1987. One hundred years of Cyanidation. CIM Bulletin
80 (905), 108–114.
Habashi, F., 1995.Gold through the ages.CIMBulletin 68 (990), 60–69.
Higgs, T.W. et al., 1995. Technical Guide for Environmental
Management of Cyanide in Mining. Mining Association of British
Columbia, Canada.
Mudder, T., 1999. Making sense of cyanide. The Gold Institute,
Washington, DC, USA, pp. 1–9.
Mudder, T. (Ed.), 2001. The cyanide guide. Mining environmental
management (special issue), The Mining Journal, London, En-
gland, p. 45.
Mudder,T., Botz,M., Smith,A. (Eds.), 2001.The cyanide compendium,
Mining Journal Books, London, England, 1000þ pages on CD.
Robbins, G., Devuyst, E., Malevich, A., Agius, R., Iamarino, P.,
Lindrall, M., 2001. Cyanide management at boliden using the Inco
SO2/air process, in: International Conference on Mining and the
Environment (Securing the Future), vol. 2, Skelleftea, Sweden, pp.
718–728.
United States Environmental Protection Agency, 1987. Extremely
hazardous substances list and threshold planning quantities:
Table 3
Statistical means of cyanide concentrations
Year Month Cyanide concentration
means
Value Pledged
to Ministry of
Environment
Detoxa
(ppm)
Decant
a
(ppm)
Detoxa
(ppm)
2001 June 0.22 0.06 1
July 0.41 0.20
August 0.32 0.13
September 0.43 0.42
October 0.38 0.32
November 0.26 0.14
December 0.38 0.13
2002 January 0.40 0.19
February 0.26 0.18
March 0.28 0.12
April 0.33 0.20
May 0.30 0.23
a
CNWAD.
698 A. Akcil / Minerals Engineering 15 (2002) 695–699emergency planning and release notification requirements. Federal
Register 52, 13378–13410.
United States Environmental Protection Agency, 1988. Ore mining
and dressing point source category effluent limitations guidelines,
40 CFR 440.
United Nations Environment Programme (UNEP), 2002. The Inter-
national cyanide management code (Draft Final Version), Paris,
France.
World Bank, 1994. Environmental health and safety guidelines,
Mining and Milling-Open Pit.
A. Akcil / Minerals Engineering 15 (2002) 695–699 699
[First application of cyanidation process in Turkish gold mining
and its environmental impacts
A. Akcil
*
Department of Mining Engineering, Mineral Processing Division, Suleyman Demirel University, TR 32260 Isparta, Turkey
Received 16 April 2002;accepted 20 July 2002
Abstract
In the history of Turkey the first use of cyanide for gold recovery has been at the Ovacik GoldMine. During one-year test period,
this mine has successfully been mining and processing after a complicated and extensive environmental impact procedure. In Turkey
about 2500 ton of sodium cyanide are used with about 240 ton of sodium cyanide being used at this mine annually. During the test
period, it has been shown that an effluent quality (CNWAD) between 0.06 ppm (min) and 1 ppm (max) was achievable after cyanide
destruction with the Inco Process. It was also found that treated effluent values (CNWAD) of process water (decant) were between
0.04 ppm (min) and 0.59 ppm (max). This paper presents a review of the cyanidation and cyanide destruction processes at the
Ovacik Gold Mine.
2002 Elsevier Science Ltd. All rights reserved.
Keywords: Cyanidation;Gold ores;Hydrometallurgy;Environmental
1. Introduction
Gold mining and electroplating industries are re-
sponsible for using large amounts of cyanide in their
respective processes. In some cases excess process solu-
tion must be treated to stringent standards and released
into the environment.
The discovery of the cyanidation process developed
from earlier attempts by alchemists to transform base
metals into gold, as well as on the emerging chemistry of
the so-called ‘‘Blue Acid’’ and its compound during the
eighteenth century. The cyanidation process arose from
the discovery that dilute cyanide solutions will dissolve
precious metals from their ores (Habashi, 1987, 1995).
Cyanide combines with and is transformed into many
related compounds. Because of its unique properties,
cyanide is used in the manufacture of metal parts and
numerous common organic products. About 1.4 million
tons of hydrogen cyanide are produced annually world-
wide, of which only about 13% is converted into sodium
cyanide and used in the extraction of gold and silver.
The remaining 87% of the hydrogen cyanide is used in
the production of a wide range of products (Mudder,
2001;Mudder et al., 2001). The allowable potable water
standards for cyanide are 0.2 ppm (United States En-
vironmental Protection Agency), 0.07 ppm (World
Health Organisation), 0.05 ppm (European Union), 0.5
ppm (World Bank) and 1 ppm (Turkish Ministry of
Environment).
Just recently, an international Cyanide Management
Code has been developed by the United Nations Envi-
ronment Programme (UNEP). For this voluntary in-
dustry code, most of participants from gold mining
industry, government, non-governmental organizations,
labor, cyanide producers and financial institutions have
worked cooperatively toward a common goal. The Code
focuses exclusively on the safe management of cyanide
at gold mines. Participation in the Code is voluntary.
Code signatories agree to follow the Codes principles
and to implement its standards of practice. Verification
and certification is accomplished through independent,
third party audits every three years. An operation is
certified when the auditor concludes that the Code is
implemented. A unique symbol may be used by those
operations certified as in compliance with the Code.
Minerals Engineering 15 (2002) 695–699
This article is also available online at:
www.elsevier.com/locate/mineng
*
Tel.: +90-246-2111240;fax: +90-246-2370434.
E-mail address: ata@mmf.sdu.edu.tr (A. Akcil).
0892-6875/02/$ - see front matter 2002 Elsevier Science Ltd. All rights reserved.
PII: S08 9 2-6 8 75 (0 2 )0 01 6 5- 6Operations are de-certified if an audit determines
that the operation is no longer in compliance (UNEP,
2002).
Even if different environmental regulations and codes
are in force in countries where cyanide is primarily used
in mining, cyanide remains an indispensable chemical in
these processes until there is a commercial, economical,
and environmental alternative. This paper presents a
review of the cyanidation and cyanide destruction pro-
cesses at the Ovacik Gold Mine.
2. Ovacik Gold Mine
The Ovacik Gold Mine is located near the western
coast of Turkey (Fig. 1). Although this ore body was
discovered in 1989, the operation finally started to re-
cover gold and silver in June 2001. The open pit shall
produce 200,000 ton/year and the underground mine
100,000 ton/year. The mine exploration programme was
initiated in 1989. Since 1989, a total of 15,000 m of holes
have been drilled in the concession area (Table 1).
In the Ovacik cyanidation plant, ore is first crushed
and then wet ground in mills to liberate gold particles.
Once ground to )38 lm, a high degree of liberation
hence recovery of gold from the ore is achieved.
2.1. Cyanidation process
Approximately 2.5 million tons of cyanide is manu-
factured annually worldwide. Turkey also used ap-
proximately 2500 ton sodium cyanide and this plant is
used 240 ton sodium cyanide annually. In the history of
Turkey, the first use of gold recovery by cyanide was at
the Ovacik Gold Mine. During a test period, ore was
successfully mined and processed after a lengthy envi-
ronmental impact procedure. After the one year test
period, the Ovacik Gold Mine has been waiting a court
decision for continuous operating.
2.2. Cyanide destruction process
As an alternative cyanide destruction process, the
Inco process (sulphur dioxide and air) was patented in
1984 (Borberly et al., 1984). For 18 years, the process
has been successfully applied at scores of gold mines
worldwide. This process is based upon conversion of
CNWAD to cyanate using a mixture of sulphur dioxide
and air with copper sulphate (CuSO4) catalyst. Due to
the need to treated the tailings slurry, the Inco process
was selected the cyanide destruction process in 1994.
The process uses sulphur dioxide, available in a va-
riety of reagent forms, plus air that is dispersed into
solution using a well-agitated vessel. Normally, the SO2/
air process is configured as a single-stage continuous
treatment facility. The technology is safe and reliable
and is selective for total cyanide detoxification. Typi-
cally, the process is capable of removing total cyanide to
less than 2 mg/l, from feeds containing total cyanide in
the range of 50–2000 mg/l (Robbins et al., 2001).
The destruction circuit was designed to destroy 8.4
kg/hr of cyanide in a tailings stream composed of 45–
48% solids (by wt.%). The slurry and cyanide flows have
been calculated using a basis of 900 tones of ore pro-
cessed per day (approximately 180 ppm CNTotal ) (Fig. 2).
Fig. 1. General view of Ovacik Gold Mine, Turkey.
Table 1
Gold potential of Ovacik Gold Mine
Ore reserves Ore (million
ton)
Grade
(g/ton)
Gold content
(ton)
Total (proven–possible–
probable)
4.19 7.6 31.87
Mineable 2.4 10 24
Fig. 2. Process scheme of chemical destruction at Ovacik Gold Mine.
696 A. Akcil / Minerals Engineering 15 (2002) 695–699In many countries there are effluent limits for the
water discharged after chemical treatment prior to being
discharged into the environment. At the Ovacik Gold
Mine there is an effluent limit for discharge of the tail-
ings into the impoundment but none discharge into the
environment. According to test results, the effluent
quality was higher at the Ovacik Gold Mine after treat-
ment than is commonly achieved in USA and Canada,
which are experienced in gold mining and cyanide pro-
cesses (Table 2).
3. Statistical results of process monitoring database
During the test period, ore has been successfully
mined and processed. Process evaluations were per-
formed for a test period of one year (June 2001–May
2002) at Ovacik Gold Mine. Detoxification is defined as
chemically decomposed wastewater discharging into the
tailings pond. Decant is defined as water recycled to the
plant from the tailings pond to use as makeup process
water. Filtered water is collected in drainage pipes at the
bottom from which water is pumped to process water
tank for reuse in the plant.
Daily and monthly results of Detox and Decant are
calculated by using statistical analysis and results of
plant performance as shown on Figs. 3 and 4.
For the Ovacik Gold Mine, the Inco cyanide de-
struction process has a capacity to decompose over 99%
of the cyanide present. The resultant CNTotal concen-
tration in the tailings is lowered to below 1 ppm, which
is the limit of national environment legislations for
CNWAD in the tailings (Akcil, 2001, 2002a,b;Akcil et al.,
2002).
During this period, it has been shown that environ-
mental limits were found between 0.06 ppm (min) and
1 ppm (max) as detoxification discharges (Detox) after
destruction by Inco process. For the process water
(Decant), limits were found between 0.04 ppm (min) and
0.59 ppm (max).
In the light of the statistical data, daily and monthly
cyanide concentrations in the treated effluent at the
Ovacik Gold Mine do not exceed those required by the
Turkish Ministry of Environment (Table 3).
Table 2
Comparision with effluent limits of Ovacik Gold Mine with international standards (Higgs, 1995;US EPA, 1987, 1988;World Bank, 1994)
Element Tailing Turkish
Ministry of
Environment
International Standards
Destruction Discharge Canada World Bank USA
Before After Dama
Environment Dama
Environment Dama
Environment Dama
Environment
CNTotal 144 <1 <1 No discharge 1 No
limit
2No
limit
1No
limit
0.2 CNWAD
Cd <0.01 <0.01 <0.01 1 0.01–0.1 0.1 0.05
Zn 1 <0.1 <0.1 5 0.2–1 1 0.75
Cu 6 0.42 0.42 5 0.05–0.3 0.1 0.15
Pb <0.05 <0.05 <0.05 2 0.05–0.2 0.6 0.3
As 2 0.005 0.005 5 0.01–1 1 –
Sb 10 0.03 0.03 5 – – –
Fe 3 0.129 0.129 10 0.3–1 2 –
Cr <0.01 <0.1 <0.1 2 0.05–0.3 1 –
Hg <0.01 0.007 0.007 0.1 0.001 0.002 0.001
a
No official limits in cyanide discharges into tailings pond.
Fig. 3. Statistical results (max–min) of Detox discharge from June
2001 to May 2002.
Fig. 4. Statistical results (max–min) of Decant discharge from June
2001 to May 2002.
A. Akcil / Minerals Engineering 15 (2002) 695–699 6974. Conclusions
Although cyanide can be toxic to humans and pro-
duce adverse effects on the environment, our knowledge
of cyanide and its related compounds is sufficient to use
it safely. Unfortunately accidents resulting from human
error have and will continue to infrequently occur.
However, the over all safety and environmental record
associated with cyanide is excellent, when compared
with other industrial chemicals. Clearly, the benefits of
cyanide outweigh its risks and over lives would be ad-
versely impacted without it and its products (Mudder,
1999).
The UNEP and the International Council on Metals
and the Environment have carried out and investigated
the accidents occurring in mines and repeated study of
environmental criteria, especially in recent years and in
detail in the last two years. With participation of all
related representative of institutions, the same code
applied to this sector. Volunteer institutions will plan
the application of the Code. The studies done in the
Ovacik Gold Mine successfully tested without exceeding
limiting values of cyanide and heavy metals concentra-
tions during one year (June 2001–May 2002).
Through scientific and engineering investigations
toxic chemicals such as cyanide can be reduced to ac-
ceptable limits or converted to non-toxic forms. For this
reason, the excavation and processing of metals and
minerals from natural sources should be carried out with
regard to environmental concerns. Through studies of
the type conducted at the Ovacik Gold Mine precau-
tions can be taken to provide an appropriate level of
environmental protection and to minimise impacts.
As a result of these studies, the following conclusions
were reached:
• During a test period, environmental criteria were not
exceeded according to the limits of the Turkish Min-
istry of Environment.
• Heavy metal concentrations in Ovacik Gold Mine
wastes are far lower than the limiting values stipu-
lated by European Union regulations for waste slur-
ries permitted to be discharged on to the land.
• A waste discharge to the tailing pond at less than
1 ppm cyanide (CNWAD).
• Recirculation of wastewater from the tailings pond to
the plant could be accomplished.
• Neither direct nor indirect discharge to the receiving
environment occurred.
Acknowledgements
The author wishes to thank the Newmont Australia
Ltd. (former Normandy Mining Co.), Turkey for per-
mission to publish the paper. The author also thanks
Dr. Terry Mudder (USA) for invaluable comments and
for his helpful collaboration. Finally, the author would
like to thank the referees for reviewing this paper.
References
Akcil, A., 2001. Cyanide versus environment: Turkeys final decision.
Mining Environmental Management, UK 9 (6), 22–23.
Akcil, A., 2002a. Turkey, mining annual review. The Mining Journal
Ltd. UK, 1–4.
Akcil, A., 2002b. Cyanide control in tailings pond: Ovacik Gold Mine,
Turkey, in: Seventh International Symposium on Environmental
Issues and Waste Management in Energy and Mineral Production
(SWEMP), Italy.
Akcil, A., Oygur, V., Ciftci, H., 2002. A case study: decomposition of
cyanide and heavy metal stabilization in Ovacik Gold Plant, in:
International Conference on Mineral Processing Technology,
Bangalore, India.
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Table 3
Statistical means of cyanide concentrations
Year Month Cyanide concentration
means
Value Pledged
to Ministry of
Environment
Detoxa
(ppm)
Decant
a
(ppm)
Detoxa
(ppm)
2001 June 0.22 0.06 1
July 0.41 0.20
August 0.32 0.13
September 0.43 0.42
October 0.38 0.32
November 0.26 0.14
December 0.38 0.13
2002 January 0.40 0.19
February 0.26 0.18
March 0.28 0.12
April 0.33 0.20
May 0.30 0.23
a
CNWAD.
698 A. Akcil / Minerals Engineering 15 (2002) 695–699emergency planning and release notification requirements. Federal
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A. Akcil / Minerals Engineering 15 (2002) 695–699 699