Nature and origin of multicomponent aerial emissions of the copper-nickel smelter complex

Valery Barcan
Lapland Biosphere Reserve, Zeleny, 8; 184505, Monchegorsk, Murmansk Prov.,
Russia Received 5 February 2002;
accepted 12 August 2002

The Severonickel Smelter Complex as well as other big nickel-copper smelter plants are the source of metallurgical dust emissions, enriched with toxic elements Ni, Cu, Pb, Zn and As. The phase composition of typical metallurgy dust is described as pentlandite (Ni,Fe)₉S₈, pyrrhotite Fe₇S₈(Nit), chalcopyrite CuFeS₂, chalcosite Cu₂S, covellite CuS, cuprite Cu₂0, tenorite CuO, and metal copper and nickel. The fine dust fractions are enriched by lead, zinc and arsenic oxides.
The obtained data can be turned to account when conducting the investigations of heavy metal behaviour in nature media, in particular soils.
© 2002 Elsevier Science Ltd. All rights reserved.

Keywords: Smelter technology; Nickel; Copper; Lead; Zinc and arsenic emissions

1. Preface

This work is accomplished on the practice of the Severonickel Smelter Complex (the town of Monchegorsk), processing sulfide raw materials. We have the basis to account that deductions may be disseminated to other similar enterprises. Dust and gaseous emissions of metallurgy plants processing sulfide materials into pure metals have similar composition, independently of location (Kola Peninsula and Taymir Peninsula in Russia, Canada, Australia, Finland, ex.), owing to similar raw materials (Polpherov, 1978) and the main metallurgy processes (Greyver, 1962; Lomako, 1968).

The production of nonferrous metals is very capital-capacious and, accordingly, inert process. The main processes used at Severonickel Complex until 1998 were described as far as 1962 (Greyver, 1962).
The smelter complex is a metallurgical enterprise with a complete production cycle, from the raw materials to the finished products—pure electrolytic metals (Ni, Co and Cu), platinum metal concentrates and sulfuric acid. In the development of enterprises of this sort, the main emphasis was placed on maximizing the total output and on achieving technological perfection. The problems associated with the environmental effect of the smelter were largely ignored, and overall, they received only low priority when selecting the technology to be used or the investment policy. The first step to essential change of the process was made at 1998—the electric melting of the ore was stopped, and the technological reconstruction of the smelter is now in progress, with the aim to reduce the volume of emissions to acceptable level. However, for the present, these changes are reversible— simply the process is divided in the space (Monchegorsk-Norilsk).

2. Introduction

The irrevocable loss of metals from the plant as slags, dust and waste was at last the time 4.5-5% of the raw material. The emissions of Ni, Cu and S0₂ are shown in Tables 1 and 2. The total emissions is found in sum so big at the last 50 years—nickel ~ 110000 tons, copper ~ 100000 tons and sulfur dioxide ~ 7 500 000 tons—that even after its complete stop, the monitoring and study of their negative influence will remain actual for many decades.

Metallurgical slag contains toxic metals in immobile insoluble forms, and the slag heaps can cover several hectares of land. Metal-containing effluents pollute the neighbouring reservoirs, but represent local pollution sources only. Contrary to this, gaseous emissions from smelters such as Severonickel and Pechenganickel complexes in the Kola Peninsula and the Norilsk Smelter Complex in Siberia are global sources of atmospheric pollution (Kryuchkov and Makarova, 1989).

Airborne industrial emissions are distributed among three media—air, water and soil. Gaseous pollutants, such as sulfur dioxide, nitrogen oxides and chlorine, are mainly present in the ambient air, although they are partly absorbed by soil and water. Particles of metallurgical dust, greater than 1 -2 um, are deposited on flat surfaces such as soil and water. Particles less than 1-2 jxm behave as gases, and remain in the air for indefinite periods and can be transported in the atmosphere for thousands kilometers (Kryuchkov and Makarova, 1989; Malachov and Zyrin, 1988).

The share of Severonickel Smelter Complex accounts for 94-96% of the total emissions of sulfur dioxide, and 100% of the emissions of nonferrous heavy metals at the central part of the Kola Peninsula (Poznyakov, 1993, 1999).

Table 1 Emissions S02 in atmosphere and utilization of sulfur at Severonickel Smelter Complex
Year	Emissions SO2 (thousand tons per year)	Utilization of sulfur of raw materials (%)	Year	Emissions SO2 (thousand tons per year)	Utilization of sulfur of raw materials (%)
1969	94	33	1985	236	35
1970	101	32	1986	251	39
1971	111	31	1987	224	45
1972	118	30	1988	212	48
1973	215	21	1989	212	48
1974	259	18	1990	233	44
1975	274	19	1991	196	43
1976	268	20	1992	182	39
1977	246	22	1993	137	41
1978	244	30	1994	98	43
1979	189	39	1995	129	32
1980	206	38	1996	110	37
1981	187	39	1997	140	38
1982	239	34	1998	88	49
1983	278	23	1999	45	-
1984	257	32	2000	45	-
			2001	44	76

The level of environmental contamination by emissions of Severonickel Smelter Complex is described as follows. The area about 4000 km² around the plant is found to be contaminated by nickel and copper by the factor 6-1500 times more than European background, dependent on the distance and direction from the pollution source (Barcan and Silina, 1996). The soils sampled from the center of this airborne pollution, including the inhabited territory of the town of Monchegorsk, were found to be contaminated by nickel and copper to levels 450 and 250 times higher in comparison to the background, respectively—9000 and 4000 mg/kg of soil (Barcan and Kovnatsky, 1998). By this reason, the plants (for example, berries, mushrooms, needles and leaves) growing over an area of at least 3000 km² around the smelter complex are unsuitable for human consumption due to the elevated nickel concentration (Barcan et al., 1998).

Extremely low velocity of soil self-purification from the absorbed toxic metals (Iimura et al., 1977; Barcan, 2002) retains the urgency of their study on influence on the nature environment.

Unpublished bibliography connected with airborne emissions of Severonickel Smelter Complex includes about 1200 names, including summaries (Doncheva, 1978; Alexeyev, 1990; Norin and Yarmishko, 1990; Kozlov et al, 1993; Tikkanen and Niemelii, 1995; Reimann et al, 1996; Evdo-kimova, 1995; Lukina and Nikonov, 1996; Kozlov and Barcan, 2000; AMAP, 1998). However, all publications are characterized by the fact that the pollution source is considered as some sort of "black box". The technological characteristic of the pollution source and the form and chemical composition of the emitted compounds are not taken into account. Despite this, the properties and composition of the compounds are undoubtedly of great importance from the point of view of their interactions with nature media.

The aims of the study are to open for the ecologists the "black box" of the smelter by means of a brief description of the specific emissions linked to the main technological steps in ore processing and to emphasise the strong necessity to take into account both the physical properties and the chemical composition of the emitted dust particles in environmental research.

Table 2 Emissions in ambient air of nickel, copper and cobalt by Severonickel Smelter Complex (ton/year)
Years	Nickel	Copper	Cobalt
1984	3110	2490	116
1985	3013	2420	82
1986	-	-	-
1987	-	-	-
1988	-	-	-
1989	-	-	-
1990	2712	1813	97
1991	2660	1740	97
1992	2118	1456	91
1993	1960	1049	89
1994	1619	934	82
1995	1366	726	56
1996	1309	700	41
1997	1350	760	37
1998	1304	874	35
1999	1128	856	32
2000	1126	873	34
2001	1212	827	44

3. The emission source

The main Ni- and Cu-containing minerals of Cu-Ni sulfide ores (Polpherov, 1978) are pentlandite (Ni,Fe)₉S₈ representing an isomorphous mixture of nickel and iron sulfides; pyrrhotite Fe₇S₈(Nit), containing solid solutions of nickel; and chalcopyrite CuFeS₂. Other sulfide minerals, e.g. pyrite FeS₂ cubanite CuFe₂S₃, occur rather rarely. Nickel is accompanied by cobalt, platinum metals, selenium, tellurium, gold and silver. The nickel content of the sulfide ores is 0.3-5.5%, copper 0.6-10% and cobalt 0.2%. The main mineral mass in the ore is magnetite (FeFe₂0₄), pyrrhotite and silicates of iron, aluminium, magnesium and calcium. The first operation is the melting of copper-nickel ores and circulating materials to form copper-nickel matte. As a result, the alloy simple sulfides—Ni₃S₂, Cu₂S and FeS, and the oxide alloy—slag—are obtained. From 13% to 25% of sulfur in the ore is emitted as sulfur dioxide in the ambient air. The dust clouds swirling up the smelter during many years consisted viz. of this gas.

The ores contain lead (0.002% average) as PbS, zinc (0.004-0.06% average) as ZnS and ZnO, and arsenic (0.005-0.03% average). The circulating products contain about 1% As as iron arsenate.
Ore smelting in the electric arc furnaces is accompanied by formation of the dust as a result of the evaporation of overheated smelt and sputtering. The gas flow carries much of the fine-grained material when feeding charge on the smelt surface in the furnace.
The gas from ore smelting is, after dust removal, subsequently emitted into the ambient air, partly through chimneys or sky-lights in the roof.
The copper-nickel matte is blown through with air and quartzite added to the iron slagging (the Bessemer process).

The bessemerizing gas contains up to 5-6% S0₂ and, after dust removal, passes to sulfuric acid production. A considerable proportion of the gas is emitted in the smelter building and subsequently passes out into the ambient air.

More gas and dust are emitted when the converter is turned off to pour out the alloy. The source of dust during besseme-rization is the formation of a multitude of small gas sprays in the turbulent alloy, and it is carried out by the gas flow.

The mixture of nickel, copper and cobalt sulfides formed as a result of the bessemerizing process—Bessemer matte— is separated by flotation into nickel and copper concentrates, and these half-finished products are subsequently treated using a number of different techniques.
The treatment of the nickel concentrate (Ni₃S₂) is not accompanied by the essential emission of gas and dust in the ambient air because S0₂ is completely used for the sulfuric acid production, after the effective preliminated dust removal.
The anode nickel undergoes electrolytic refining to give the finished commercial product—pure electrolytic nickel (99.97-99.99% Ni).
The half of sulfur, contained in copper concentrate, is emitted as S0₂ in the ambient air, as well as copper-bearing dust.
The obtained rough copper is refined by blistering and then electrolytic refining to give the finished commercial product—pure electrolytic copper (99.95-99.99% Cu). The content of three metals in the liquid effluent formed during the hydrometallurgical production of nickel and copper is given in Table 3.
All the dust emission sources in the process chain are equipped with dust removal systems, but the large losses of metal in the form of dust are due to violations of technological principles, aged and defective equipment, etc. However, the losses could be relatively easily reduced. The total costs of the current gas purification systems, including depreciations, are only a few percent of production costs. Maximum tolerable emissions of S0₂ by Severonickel Smelter not more than 13 000-25 000 tons per year and emissions of nonferrous metals are totally not permissible (Kryuchkov and Makarova, 1989; Barcan, 1992).

The technological reconstruction of the Smelter is necessary for this aim, but this question is out of the framework of this paper.
The Severonickel Smelter is also a source of gaseous emissions of C0₂, CO, NOx, phenol, formaldehyde and polycyclic aromatic hydrocarbons, mainly benz(a)pyrene, sulfuric acid and sulfuric anhydride, hydrogen sulfide, chlorine, nickel tetracarbonyl, vanadium compounds, selenium dioxide and tellurium dioxide and manganese oxides (Table 4). Carbon and nitrogen oxides are formed as a result of the combustion of masut in the steam boiler and in the blister refining furnaces during the burning of self-coked electrodes in the electrical arc furnaces and the reduction of nickel monoxide by coke. The source of phenol and formaldehyde is the production of slag wadding in which phenol-formaldehyde resin is used as binder. 3,4-benz(a)pyrene is mainly formed during the burning of self-coked electrodes and masut combustion. The source of vanadium emissions is the combustion of masut, and of manganese during the melting of alloyed steel in the repair shop. Selenium, tellurium and cobalt are emitted together with nickel and copper. Nickel tetracarbonyl is emitted during the production of pure nickel powder, hydroaerosols of nickel and copper and chlorine—with ventilation gases of hydrometal shops. The source of sulfuric acid and sulfuric anhydride is sulfuric acid production. Table 4 is compiled by data of State Statistic reports, based on reports of the Environment Protection Department of the Severonickel Smelter Complex.

Table 3 Entrance of metals with sewage in natural reservoirs by Severonickel Smelter Complex (ton/year)
Years	Nickel	Copper	Cobalt
1985	284	12	3.5
1986	213	5	5
1987	184	3	3
1988	138	2	2
1989	131	4	22.5
1990	123	5	2
1991	147	7	3
1992	84	5	2
1993	94	3	2.5
1994	54	2.5	1.5
1995	46	3	3
1996	54	4	2
1997	44	2.5	1.5
1998	32	3.5	0.5
1999	32	2.5	0.5
2000	20	2.5	0.6
2001	18	1.7	0.3

4. Investigation of metallurgical dusts of Severonickel Smelter Complex

4.1. Materials and methods: dust sampling and analysis

The dust samples were taken either from the gas flow near to the smoke ducts using special traps made from heat-resistant fabric, or from the last section of the electrostatic filters. The samples were always taken when the plant was working. The element content in the dust was determined by standard metallography methods (Volynsky, 1947; Vachro-meev, 1960; Isaenko et al, 1978). A total of 20 major elements were determined in the dust samples: Fe, Si, Al, Ca, Mg, S, Ni, Cu, Co, As, Cd, Cr, Mn, Pb, Zn, Se, Mo, Ti, V and W. The chemical analyses were conducted after extraction of the dust samples with a mixture of concentrated HC1 and HN0₃ (3:1, aqua regia). The total metal concentrations in the solution were determined as follows: Ni, Cu, Co, Fe, Zn and Pb by flame atomic absorption spectrometry on a Perkin Elmer 303 0B spectrometer; Al, Cr, Mn, Se, V, W, Ti, Sr, Mo, Ca and Mg on an AtomScan 25 emission ICP spectrometer (Thermo Jarrell Ash) and Cd and As on a Perkin Elmer 3030B spectrometer using a furnace cuvette. The total sulfur concentration in the dust was determined on a LECO CS-444 instrument by ignition in a current of oxygen and sulfur dioxide determination by infrared detection (LECO, 1991). The total silicon concentration in the dust was determined by a standard method involving alkaline melting (Ponomaryov, 1955).

Table 4 Pollutant emissions in ambient air by Severonickel Smelter Complex (ton/year)
	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2001
Hydrocarbons	600	600	600	600	400	400	400	400	400	400	400	313
Benz(a)pyrene	-	-	0.06	0.06	0.06	0.053	0.014	0.014	0.015	0.013	0.013	0.010
H2SO4	318	302	262	245	251	197	206	267	184	212	195	115
H2S	28	28	28	28	18	18	18	18	18	18	18	16
Cl2	425	396	365	365	341	341	242	222	208	203	196	86
Phenol	8.6	8.6	8.6	8.6	1.7	1.7	0.9	0.8	0.7	0.7	0.7	0.5
Formaldehyde	553	553	553	553	108	64	33	28	24	4	4	3
Ni hydroaerosol	199	199	178	178	157	85	85	77	74	62	60	58
Cu hydroaerosol	0.7	0.7	0.7	0.7	0.7	0.7	0.7	0.7	0.7	0.7	0.7	2
Ni(CO)4	1.6	1.6	1.5	1.5	1.5	1.5	1.5	1.5	1.5	-	-	-
V205	48	48	48	57	60	40	39	37	46	47	45	62
Mn203	0.13	0.13	0.13	0.13	0.14	0.14	0.14	0.14	0.14	0.14	0.14	0.14
Se02	0.9	0.9	0.9	0.9	1.4	0.025	0.025	0.08	0.8	0.8	0.8	0.9
Te02	0.09	0.09	0.09	0.09	0.09	0.005	0.005	0.005	0.005	0.02	0.02	0.02

4.2. Results

The phase and chemical composition of the dusts, emitted by metallurgical processes and precipitated on the landscapes, are formed by the composition of initial and obtained products. At the same time, some elements like lead, zinc and arsenic are concentrated viz. in dusts, owing to high temperature volatility of their compounds.

The dust from the ore smelting mainly consists of the slag-forming compounds of iron, aluminium, magnesium, calcium and silicon, as well as sulfide minerals of nickel, copper and iron, which are both present in the ore (pen-tlandite, pyrrotite and chalcopyrite) and are formed during smelting—Ni₃S₂, FeS₂ and CuS (Table 5). The dust considerably is enriched with As — to 0.1-0.6%, Pb — to 0.2-0.3% and Zn — to 0.4-1.4%, compared to the content in the ore. The sum of these elements in dust is equal or even more than that of nickel and copper (Table 6).

Table 5 Phase composition of metallurgical dusts of Severonickel Smelter Complex
Process	Main phases
Melting of copper-nickel ores and concentrates to obtain copper-nickel matte	pentlandite (Fe,Ni)9S8 pyrrotite Fe7S8 chalcopyrite CuFeS2 khyslevudite Ni3S2 pyrite FeS2 covellite CuS silicates of Fe, As, Mg, Ca As205 PbO ZnO
Bessemerizing of copper-nickel matte	khyslevudite Ni3S2 Covellite CuS Ni met As205 PbO ZnO iron silicates
Processing of copper concentrate of matte flotation (united dust of reverberatory melting, bessemerizing of white matte and blister refining of rough copper)	chalcosite Cu2S cuprite Cu20 tenorite CuO Cu met
Kilning of nickel concentrate of matte flotation	khyslevudite Ni3S2 protoxide NiO Ni met

The main structural components in the dust derived from the bessemerizing of copper-nickel matte include iron silicates, khyslevudite Ni₃S₂, covellite CuS and metal nickel (Table 5). The dust is enriched with As to 0.7-2%, Pb to 0.6-1.4% and Zn to 0.8-1.8%, which is equal or more than the content of nickel and copper (Table 6). The elevated molybdenum content is caused by loading nonferrous scrap metal into the converters. The dust produced during copper production mainly consists of chalcosite Cu₂S, metal copper, cuprite Cu₂0 and tenorite CuO (Table 5). Copper is the main component (75%), and the following elements are iron, nickel and sulfur (Table 6).

The main structural components in the dust produced during the kilning of the Ni concentrate includes khyslevudite Ni₃S₂, protoxide NiO and metal nickel (Table 5). Nickel (33-45%), copper and iron are predominant (Table 6). The dust contains also considerable amounts of arsenic, lead, zinc and selenium. Sulfide copper-nickel ores, especially those from Norilsk, contain considerable amounts of platinum metals, gold and silver (Polpherov, 1978). The soils around Monchegorsk contain elevated concentrations of silver (Barcan and Kovnatsky, 1998).

The sum of elements in Table 6 is less than 100%. The rest includes oxygen, carbon, sorbed gases and other undetermined elements.
Thus, the main metal-containing compounds deposited on the landscape in the form of dust emissions from the smelter are pentlandite (Ni,Fe)₉S₈, pyrrotite Fe₇Sg(Nit), chalcopyrite CuFeS₂, chalcosite Cu₂S, covellite CuS, cuprite Cu₂0, tenorite CuO, and metal copper and nickel. The fine fractions of the dust are enriched with lead, arsenic and zinc. The proportion of dust derived from different sources (metallurgical processes) varies according to the raw materials and the condition of the gas cleaning systems.

5. Conclusion

It is shown on the example of the copper-nickel Severonickel Smelter Complex that metallurgical dusts of non-ferrous plants are enriched with the toxic nonferrous metals: nickel, cobalt, copper, lead, zinc and arsenic.
The phase composition of typical metallurgy dust is described as pentlandite (Ni,Fe)₉Sg, pyrrotite Fe₇S₈(NiT), chalcopyrite CuFeS₂, chalcosite Cu₂S, covellite CuS, cuprite Cu₂0, tenorite CuO, and metal copper and nickel.

The fine dust fractions are enriched by lead, zinc and arsenic oxides.
The obtained data can be turned to account when conducting the investigations of heavy metal behaviour in nature media, in particular soils.

Table 6 Concentrations of predominant elements in dusts of the main pyrometallurgical processes of Severonickel Smelter Complex
Element	Detection limit (%)	Process 1	Process 2	Process 3	Process 4
Al	0.0025	1.3-3.8 (1-4)	1.0 (1)	< 0.0025 (1)	-
As	0.0125	0.1-0.6 (1-6)	0.7-2.0 (1-3)	0.01 (1-5)	0.07-0.26 (1-5)
Ca	0.0025	1.0-2.3 (1-4)	0.35 (1)	< 0.0025 (1)	-
Cd	0.0025	0.02-0.03 (1-3)	0.04 (1)	-	-
Co	0.0125	0.05-0.20 (1-6)	0.2-0.6 (1-3)	0.03-0.50 (1-10)	0.9-1.5 (1-5)
Cr	0.0125	0.01-0.06 (1-2)	0.04 (1)
Cu	0.0125	1.3-4.3 (1-6)	3.1-5.3 (1-3)	24.1-76.3 (1-10)	2.0-6.4 (1-5)
Fe	0.0125	1.1-33.8 (1-6)	12.4-15.1 (1-3)	1.5-16.2 (1-10)	2.8-4.5 (1-5)
Mg	0.0025	2.3-5.1 (1-4)	0.3 (1)	< 0.0025 (1)	-
Mn	0.0125	0.06-0.07 (1-3)	0.05 (1)	-	-
Mo	0.0125	0.02-0.04 (1-2)	0.2 (1)	-	-
Ni	0.0025	1.3-8.4 (1-6)	3.1-6.4 (1-3)	0.9-11.0 (1-10)	32.9-45.4 (1-5)
Pb	0.0125	0.02-0.30 (1-5)	0.6-1.4 (1-3)	0.01-0.02 (1-4)	0.04-0.36 (1-5)
Stotal	0.0005	3.2-8.3 (1-5)	8.0-12.0 (1-2)	3.1-15.7 (1-10)	2.9-10.9 (1-5)
Se	0.0125	< 0.01 (1-4)	0.04 (1)	-	0.07-1.0 (1-5)
Si	0.01	1.5-15.0 (1-4)	2.4 (1)	0.2 (1)	-
Ti	0.0125	0.01-0.10 (1-3)	0.1 (1)	-	-
V	0.0125	< 0.01 (1-3)	< 0.01 (1)	-	-
W	0.0125	0.03-0.09 (1-2)	-	-	-
Zn	0.0020	0.4-1.4 (1-5)	0.8-1.8 (1)	0.01-0.02 (1-4)	0.002-0.17 (1-5)

"-" No data.
Processes 1 - Melting of copper-nickel ores and concentrates to obtain copper-nickel matte.
Processes 2 - Bessemerizing of copper-nickel matte.
Processes 3 - Treatment of copper concentrate (united dust of reverberatory melting, bessemerizing of white matte and blister refining of rough copper).
Processes 4 - Kilning of nickel concentrate of matte flotation.
In brackets - number of samples.

Acknowledgements

The author thanks Dr. Mikhail Kozlov, Senior Resercher from the University of Turku, for discussions, and Dr. John Derome, Senior Scientist from the Finnish Forest Research Institute, for help with the English language.

References

Alexeyev VA, editor. Forest ecosystems and atmospheric pollution. Leningrad: Nauka; 1990 [200 pp., in Russian].
AMAP. Arctic pollution issues: a state of the Arctic environment report. Oslo, Norway: AMAP; 1998 [188 pp.]. Barcan V. The experience of lead dioxide absorbers use for sulfur dioxide evaluation in ambient air. Ecology 1992;4:37-44 (in Russian).

Barcan V. Leaching of nickel and copper from a soil contaminated by metallurgical dust. Environmental International 2002;28:63-8.

Barcan V, Kovnatsky E. Soil surface geochemical anomaly around the copper-nickel metallurgical smelter. Water, Air and Soil Pollution 1998;103:197-218.

Barcan V, Silina A. The appraisal of snow sampling for environment pollution valuation. Water, Air, and Soil Pollution 1996;89:49-65.

Barcan V, Kovnatsky E, Smetannikova M. Absorption of heavy metals in wild berries and edible mushrooms in an area affected by smelter emissions. Water, Air, and Soil Pollution 1998;103:173-95.

Doncheva A. Landscape in the zone of industrial impact. Moscow: "Les-naya Promyshlennost" publisher house, 1978 (in Russian).

Evdokimova GA. Ecological and microbiological foundations of soil protection in the far north. Kola Sci Centre publishing house, Apatity; 1995 [168 pp., in Russian].

Greyver N, editor. The basic science of metallurgy, vol. 2. Heavy Metals, Moscow; [792 pp., in Russian]. Timura K, Ito H, Chino M, Morishita T. Behaviour of contamination heavy metals in soil-plant system. Proc Int Sem SEFMIA, Tokyo 1977;357.

Isaenko MP, Borishanskaya SS, Afanasieva EL. Definition of main ore minerals in reflecting light. M; 1978 [253 pp., in Russian]. Kozlov M, Barcan V. Environmental contamination in the central part of the Kola Peninsula: history, documentation and perception. AMBIO 2000; 29(8):512-7. Kozlov MV, Haukioja E, Yarmishko VT, editors. Aerial pollution in Kola Peninsula. Proceedings of the International Workshop, 14-16 April 1992, St. Petersburg, Russia. Apatity, Kola Sci Centre; 1993 [418 pp.].

Kryuchkov VV, Makarova TD. Airborne affect on ecosystems of the Kola North. Apatity; 1989 [96 pp., in Russian]. LECO, CS-444. Instruction manual. New York: LECO publishing house; 1991.

Lomako PF. Nonferrous metallurgy of Canada. Moscow: "Heavy Metals"; [380 pp.].

Lukina NV, Nikonov VV. Biogeochemical cycles in the northern forests subjected to air pollution. Kola Sci Centre, Apatity; 1996 [Pt. 1, 213 pp. and pt.2, 192 pp., in Russian].

Malaehov ST, Zyrin HG. Calculations of limit tolerable emissions by the heavy metal soil content. Heavy metals on environment and nature protection. Pros of ÀÍ-Union Conference, Moscow University, Moscow, Dec. 1987. 1988;93-9 [in Russian].

Norin BN, Yarmishko VT, editors. The influence of industrial atmospheric pollution on pine forests of the Kola Peninsula. Leningrad: Komarov Botanical Institute; 1990 [195 pp., in Russian].

Polpherov DV. Geology, geochemistry and origin of deposits of copper-nickel sulfide ores. "Nedra" (Depths). L; 1978 [294 pp., in Russian].

Ponomaryov AI. Methods of chemical analysis of minerals and rocks Silicates and carbonates, vol. 1. Moscow: Academy of Sciences of USSR publishing house, 1955 [Moscow, in Russian].

Poznyakov VY The Severonikel Smelter Complex: history of development. In: Kozlov MV, Haukioja E, Yarmishko VT, editors. Aerial pollution in Kola Peninsula: Proceedings of the International Workshop, 14-16 April 1992, St. Petersburg, Russia. Apatity, Kola Sci. Centre; 1993. p. 16-9.

Poznyakov VY. The Severonikel. M., Publishing House "Ore and Metals", 1999 [432 pp., in Russian].

Reimann C, Chekushin VA, Ayras M (Eds.), Kola Project—International Report, Catchment study 1994. Trondheim, Geological Survey of Norway. Report 96.088. Trondheim, Norway; 1996. 450 pp.

Tikkanen E, Niemela I, editors. Kola Peninsula pollutants and forest ecosystems in Lapland. Final report of the Lapland Forest Damage project. Rovaniemi, Finland: Rovaniemi Finnish Forest Research Institute; 1995 [82 pp.].

Vachromeev SA. Handbook on mineralography. 1960 [198 pp., in Russian].

Volynsky IS. Determination of ore minerals by microscope (Method guide), vol. 1. M.-L.; 1947 [267 pp., in Russian].