Ecology

Medvedeva N.P., PhD in Economics, Filippov P.A., PhD in Technical Sciences

Novosibirsk state technical university, Russia

Institute of Mining, Siberian Branch, Russian Academy of Sciences, Russia

Geoecological and economic evaluation of technogenic mineral formation of mines in Siberia

ANNOTATION: The problems of mine dumps maintenance and problems of development of technogenic mineral formations that contain ferrous, non-ferrous, rare, precious metals and that are interesting as a source of processed raw materials for Ore Mining and Processing Industrial Complexes are covered.

Mining, processing and development of mineral resources is inevitably followed by the formation of a significant volume of the mined and processed waste material. Thus mines and iron ore processing plants in Siberia possess voluminous dumps of waste materials (technogenic formations) that occupy huge areas. These dumps accumulate useful and toxic elements [1]. The content of iron in some dumps often exceeds the content of iron in the mined ores to be processed. This is in particular true for the old dumps which had been formed in the first half of the previous century when a complex study of mineral resources was not taken into due consideration and the treatment of iron ore deposits used to derive only one element - Fe. More than 50% of iron was left in the wastes from processing plants, some other useful minerals were lost in waste products as well. So far the iron ore dumps of the Siberian region on the territory of more than 500 th. m² have accumulated about 200 mln. t. of tails (table 1). A part of them is hazardous and needs to be isolated, another part contains useful elements and should be retreated.

Table 1.

Tails of ore processing in mine dumps

Company name	Quantity, mln.t.	Area, ha		Useful elements
Mines
Sheregeshsky	23,2	50,9		Fe, Mn, Zn, Au
Kazsky	7,2	6,3		Cu, Zn, Au
Tashtagolsky	0,3	0,2		Fe
Abakansky	20,1	28,0		Co, Cu, Ni
Teysky	21,2	19,l		Co, Zn
Irbinsky	6,7	4,7		Co, Cu, Zn
Processing plants
Mundibashskaya	30,1	60,1	Au, Ag, Zn
Abagurskaya	89,1	385,2	Zn, Cr, Co
Total	198,1	554,3	-

The natural wind erosion of mine dumps provokes venting into the air of a large amount of dust which pollutes agricultural and forestry areas. The presence of sulphide minerals in mine tails contributes to the intense development of oxidation processes which result in the release of gold, nickel and other metals from a crystalline lattice. The same oxidation processes result in the formation of environmentally hazardous compounds of sulphur, arsenic and other elements which negatively affect the biological environment [2]. The content of chemical elements in the dumps and soils of the Teysky mine is given in table 2.

Table 2.

Content of chemical elements (mg/kg) in mine wastes and their allowable concentrations

Element	Name of dump			Maximum allowable concentration for soils	Approxible allowable concentration for soils	Clark in the Earth’s crust
	Severny	Juzhny	Shlamovy
I substance hazard category
As	7,9	17,3	37,4		5,0	1,7
Cd	0,3	0,21	0,495		1,0	0,13
Hg	0,03	0,03	0,03	2,1		0,083
Zn	382,9	41,8	62,0		110,0	83,0
II substance hazard category
B	54,3	86,4	192,0			12,0
Co	3,2	7,0	46,8		12,0	18,0
Ni	16,7	14,4	27,0		40,0	58,0
Cr	75,9	35,7	76			83,0
Cu	874,4	392,3	63,9		66,0	47,0
Mo	2,0	2,3	30,0			1,1
III substance hazard category
Ba	24,6	49,8	138,0			650,0
V	53,3	50,0	82,5	150,0		90,0
Mn	448,0	674,0	938,0	1500,0		1000,0
Sr	98,1	121,7	48,9			3430,0
Radioactive elements
U	5,8	7,4	19,0			2,5
Th	3,2	1,3	2,7			13,0

Arcenic and zink both having the first substance hazard category as well as copper and cobalt (the second hazard category) significantly exceed the approxible allowable concentration of heavy metals in mine dumps.

The dumps are referred to toxicity category IV, they belong to the high and medium pollution rate by the summary parameter of pollution.

Many useful elements (Fe, Co, Au, Ag and others) occur in the technogenic dumps that have been formed by the present time. These elements are of industrial interest for the retreatment of the mine production wastes.

The studies [3] state that the iron content in the dumps goes up to 22% and the use of this raw material is efficient enough and can be compared to the iron ore processing at the productive mines by its economic parameters.

Cobalt from mine dumps is of industrial significance and should be a subject to systematic scientific studies to develop contemporary techniques of waste treatment in order to obtain the sulphide concentrate for a metallurgical extraction. The experimental floatation concentration of debris at the Irbinsky mine enabled to obtain the pyrite concentrate where copper, cobalt and zinc content was up to 6.7 %; 0.42 % and 0.55 % yielding 87,0; 52,0 and 63,6 % correspondingly.

More than 30 mln. t. of tails presented by a fine material (-2,0 + 0,045 mm) are concentrated at the dumps of the Mundibashskaya mine. The precious metals gold and silver in tailings are of the greatest interest. Their content in core samples varies: Au = 0,1-1,2 (average weighted 0,616) g/t, Ag = 0,5-7,0 g/t. Gold can be economically extracted with the use of contemporary processing techniques and first of all the technique of gravity separation with the use of concentrating table and centrifugal separators. With the use of centrifugal separation the maximal gold extraction made up 93% with the gold concentration rate from 8 to 23 units (depending on the head grade of gold in a sample).

Thus the conclusion about the great significance of technogenic formations of the Siberian mine complex and the possibilities of production of valuable, rare and precious metals as well as construction materials for the Russian industry can be made.

The industrial significance of dumps retreatment should also consider the ecological component – the preventable damage to the environment caused by discharges and exhausts of harmful components and compounds into the water basins and atmosphere. An important economic and social aspect for towns and settlements is the recovery of recultivated landscapes particularly in black soil and recreation areas.

References:

1. Filippov, P. A. 2008. Potentials of technogenic formations in mines of West Siberia. Journal of Mining Science, No. 4, 2008, pp.71-77.

2. Medvedeva N.P., Filippov P.A. On timeliness of technogenic raw materials processing. Materiály VIII mezinárodní vědecko - praktická conference «Vědecký pokrok na přelomu tysyachalety - 2012». - Díl 25. Ekologie. Zeměpis a geologie: Praha. Publishing House «Education and Science». – pp. 45-47.

3. P.A. Filippov, S.A. Neverov, A.A. Neverov. Technogenic Iron Ore Formations in Siberia as a Secondary Resource for Production of Ferrous, Rare, Non-Ferrous and Noble Metals // International Symposium. «Orebody Modelling and Strategic Mine Planning: Old and new dimensions in a changing world» - Australia, Perth, The Australian Institute of Mining and Metallurgy.-2009. - pp. 131-135.