Chemical Composition of Mine Waters of Gold Ore Deposits of the Kuznetsk Alatau

CHEMICAL COMPOSITION OF MINE WATERS OF GOLD-ORE DEPOSITS OF THE KUZNETSK ALATAU

A. D. MIKOV

(Presented by the seminar of the Department of Hydrogeology)

The article presents materials on the chemistry of mine waters of the Central, Komsomolsk, Berikul, and Natalyevsk gold-ore deposits in the Kuznetsk Alatau.

The first three of the indicated deposits are typical vein quartz–sulfide formations. Their ore bodies are characterized, as a rule, by small thickness (0.1–1.0 m) with considerable extent (the first hundreds of meters) along dip and strike.

The enclosing rocks at the Central deposit are granodiorites; at the Komsomolsk deposit, an intrusion of gabbro and gabbro-diorites. At the Berikul deposit, however, most of the veins occur within a sequence of basic porphyrites. The veins at the deposits are usually confined to two or three systems of fractures. Their dip angle varies from 5 to 75°. Veins with medium and steep dip angles predominate. The mineralogical composition of the ores is rather complex, although it is not distinguished by great diversity. The vein minerals are represented by quartz, calcite, and ankerite. The latter are of sharply subordinate importance. The principal ore minerals, the amount of which usually does not exceed 10–15%, are pyrite, arsenopyrite, pyrrhotite, chalcopyrite, sphalerite, galena, and native gold. Among them, pyrite and arsenopyrite sharply predominate. Deviations in mineral composition are observed in a number of veins. Thus, the Kavkazskaya (Yubileynaya mine), Uralskaya, and Tumashevskaya veins of the Central deposit are characterized by an extremely low arsenopyrite content, while the Central vein of the same deposit is distinguished by an extreme diversity of ore minerals. In addition to the minerals listed above, the presence of pale ore, bismuthinite, cubanite, native silver, loellingite, tetradymite, and others may be noted in it, although their content is very limited.

The most widespread in the veins are pyrite–arsenopyrite and polymetallic mineralization. Often they coincide spatially. The distribution of ore minerals in the plane of the veins is uneven. Along with barren intervals, enriched sections—ore shoots—are encountered. They have various sizes and shapes and are usually characterized by a rather steep inclination. According to V. I. Bazhenov [2], they are confined to zones of increased fracturing.

At the Natalyevsk deposit, the ore bodies are represented by lenses of skarns, the dimensions of which along strike and dip are limited to the first tens of meters, with a thickness of 4–10 m. These are located ...

ore bodies, as a rule, in the carbonate sequence. The most widespread are skarns of diopside–tremolite composition with superimposed gold–copper–bismuth mineralization. The ore minerals—chalcopyrite, arsenopyrite, pyrite, bornite, pyrrhotite, bismuthine (among them chalcopyrite sharply predominates)—are located in the skarns in disseminated form, sometimes forming nest-like accumulations up to 0.5–1.0 m in size.

The oxidation zone at all the indicated deposits is expressed rather clearly. The development of oxidized ores as a whole is limited to a depth of 30–40 m, descending in some veins to 70–85 m.

The presence of numerous dislocations cutting the ore bodies, as well as the confinement of enriched sections of veins to zones of increased fracturing, promoted the circulation of groundwater. Of greatest interest to us are mine waters. They are formed during the circulation of waters within the ore body and chiefly through mined-out blocks.

At the above-mentioned deposits, 8 samples of mine waters were taken for general chemical analysis. The results of these analyses, partly supplemented by data from other authors, are given in Tables Nos. 1 and 2. For comparison, analyses of waters of some surface watercourses are placed in these same tables.

Figure 1 gives a diagram of the chemical composition of mine waters of gold-ore deposits of the northern part of the Kuznetsk Alatau, the Southern Urals, and North America. The initial data for constructing the diagram are given in Tables Nos. 3, 4, 5. From the diagram presented it is evident that the character of mine waters in gold-ore deposits

Table 1

Results of chemical analysis of natural and mine waters of the Central deposit

Note: samples Nos. 1–4, 9 are given according to data from the laboratory of the Central Research Institute for Geological Prospecting; Nos. 5–8 were taken by the author.

Table 2

Data of chemical analysis of natural and mine waters of the Komsomolskoye, Berikulskoye, and Natalyevskoye deposits

Note. Analyses Nos. 10, 11 and 16, 17 are based on materials of the Martaiga expedition; Nos. 12–15 were sampled by the author; the analyses were performed in the hydrogeochemical laboratory of the Tomsk Polytechnic Institute.

Fig. 1. Diagram of the chemical composition of mine waters of gold-ore deposits of the northern part of the Kuznetsk Alatau (crosses), the Southern Urals (circles), and North America (triangles).

Table 3

Content of SO₄, Cl, and HCO₂ in mine waters of the northern part of the Kuznetsk Alatau

Table 4

Content of SO₄, Cl, and CO₃ in mine waters of the Southern Urals according to M. N. Albov [1]

of these regions differs: for deposits of North America, predominantly sulfate waters are characteristic; for deposits of the Southern Urals, chloride waters; and for deposits of the Kuznetsk Alatau, hydrocarbonate waters.

To determine the content of microcomponents in mine waters, 39 water samples were taken. Most of the concentrates (25) were obtained by coprecipitation according to the TPI method [4]. The remaining 14 samples were obtained by evaporation. Obtaining concentrates by two different methods showed the identity of the analytical results, but it should be noted that with

Table 5

Content of SO₄, Cl, and CO₃ in mine waters of North America according to V. Emmons [5]

Legend:
■ >10%; ■ 1–10%; □ 0.1–1%; □ 0.01–0.1%; □ 0.001–0.01%; □ >0.001%, traces.

Fig. 2. Results of spectral analysis of the dry residue of mine waters.

co-precipitation yielded a more complete set of microcomponents. The results of spectral analysis of the concentrates are presented in Figs. 2 and 3. From the data given it is evident that the mine waters are highly mineralized. Gold was not detected in the samples. Silver is present in a number of samples, and its content ranges from traces to 0.00n%. Copper, lead, and zinc were noted in almost all samples in amounts from 0.000n to 0.n%. It is necessary to note the presence, in almost all samples, of nickel, manganese, arsenic, strontium, and certain other elements. In general, the composition of elements in mine waters corresponds to their content in the ores and enclosing rocks. As spectral analyses show, the composition of the waters responds very sensitively to changes in the composition of the primary ores in one vein or another, which was already noted by the author [3] in describing the recent mineral neoformations of the Central deposit, which are precipitates of mine waters. Thus, for example, along the Kavkazskaya vein (Yubileinaya mine), Uralskaya, and Tumashevskaya of the Central mine, a reduced arsenic content was noted in comparison with the veins of Central

Fig. 3. Results of spectral analysis of concentrates of mine waters, obtained by the TPI method; conventional symbols are the same as in Fig. 2.

and others (Krasnaya mine) of the deposit of the same name, which is correlated with data on the distribution of arsenopyrite in the ores of these veins.

All the mine waters studied are characterized by high pH values, equal to 6.0–8.2, i.e., from weakly acidic to weakly alkaline. This may be explained by the fact that the mine waters were sampled in mine workings, and, in the presence of low-yield ore veins, waters of the oxidation zone are strongly diluted and neutralized by waters of the enclosing rocks. Within the ore body they should have a lower pH value.

Since no signs of gold were detected in any concentrate of the mine waters, in the summer of 1962 a large water sample of 10 liters was taken at the Tsentralny mine. The sample was taken at the upper drainage level (level 87 m) of the Krasnaya shaft. To precipitate the noble metal, the method of sorption by wood charcoal was used [1]. In the resulting precipitate, assay analysis determined the presence of traces of gold.

From the materials presented, several conclusions may be drawn: 1. The mine waters studied, in terms of their chemical composition, are bicarbonate–sulfate–chloride waters. 2. Spectral analysis of the concentrates of mine waters established the presence, in most samples, of copper, lead, zinc, and arsenic, and in a number of samples also silver, cobalt, nickel, and other elements. 3. The microcomponent composition of waters from one vein or another reflects the composition of their primary ores.

LITERATURE

1. M. N. Al’bov. Secondary Zoning of Gold-Ore Deposits of the Urals. Gosgeoltekhizdat, 1960.

2. V. I. Bazhenov. Geology and structure of the Tsentralny ore field. Materials of a scientific seminar on the study of gold-ore deposits of Siberia. TSU Publishing House, Tomsk, 1966.

3. A. D. Mikov. On contemporary mineral neoformations in quartz-sulfide veins of the Tsentralny deposit. Izvestiya TPI, vol. 166, 1967.

4. P. A. Udodov, I. P. Onufrinok, Yu. S. Parilov. Experience of hydrogeochemical investigations in Siberia. Gosgeoltekhizdat, Moscow, 1962.

5. V. Emmons. Secondary Enrichment of Ore Deposits. ONTI, 1935.