RU2579578C2 - Method for low-cost treatment and disposal of mining wastes - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention can be used in the mining industry for the purification and recycling of metal-bearing weakly acidic pit water in a bog-mountainous terrain. For carrying out the process, after neutralization with an alkaline reagent haul water fed to the natural geochemical barrier in the form of peat deposits fen. Contained in water salts of metals accumulate natural sorbent and precipitated in natural geochemical barrier as an insoluble organo-mineral complex. Resulting permanent or temporary watercourse fed purified according to the terrain in the direction of the stream or river. Fen peat deposits as a natural sorbent used in view of the sorption capacity of peat fen calculated by cation exchange capacity of peat with respect to the cation exchange capacity of the metal ions contained in the quarry waters.

EFFECT: method provides an efficient and low-cost technologies pit water cleaning helps prevent the intense migration of the metal salts in natural systems.

2 cl, 2 tbl, 2 ex

Description

The invention relates to the mining industry and can improve the efficiency of utilization and purification of slightly acidic career waters with a high content of metals, reduce the risk of industrial pollution of surface waters in the process of developing mineral resources.

Currently, weakly acidic metal-bearing quarry waters, as a rule, are subjected to liming treatment before being discharged into the surface hydrogrid (rivers), or are discharged directly without any treatment. This led to the fact that all the rivers of the Sverdlovsk region are to one degree or another contaminated with metal salts, and in places of “old” discharges, bottom sediments that have accumulated metal salts are sources of secondary pollution of river waters.

To organize such a discharge, it is necessary to develop maximum permissible discharges (MPD) according to the standard methodology (calculated for dilution with river water).

The disadvantage of this approach is the underestimation of the sorption peat deposits of the swamp. In addition, the reserves of peat deposits of lowland marshes in the Ural region are significant. Therefore, in the interests of sustainable development of the region, the proposed below method of low-cost cleaning and disposal of mining waste allows to use local resources of renewable raw materials, such as peat, one of the few reproducible types of minerals.

A known method of neutralizing wastewater containing sulfathions with an alkaline reagent - lime (Yakovlev S.V., Karelin Y.A., Laskov Yu.M. Purification of industrial wastewater. M. Stroyizdat, 1985. S. 104).

Significant disadvantages of the method are the formation of a supersaturated solution of gypsum, as well as a large volume of sediment, which is a suspension of colloidal particles. The sludge is extremely difficult to compact and dehydrate for disposal.

A known method of neutralizing acidic quarry and basement waters of mining enterprises containing sulfates.

To implement the method, acidic quarry waters are neutralized with milk of lime and precipitated suspended particles are precipitated in the presence of a flocculant and pyrite dump tailings of the ore preparation plant, after which they are mixed and settled.

This method allows to reduce the volume of sludge, but requires further dehydration and disposal (patent No. 2355647, C02F 1/66, C02F 1/56, publ. 20.05. 2009).

A known method of dummy-free storage and disposal of gold mining waste in mountainous terrain.

The method includes mixing production waste with carbonates, then additional input of crusher brucite, lignin, while the storage location is covered with a layer of insulating waterproof film and compacted. For the safe functioning of the storage in mountainous terrain, drainage and drainage of storm and melt water in the form of a drainage trench with their subsequent treatment in settling ponds (patent No. 2277020, B09B 1/00, B09B 3/00, publ. 05.27.2006, is provided. )

However, for the implementation of this method, it is necessary to create artificial structures, use a complex of technical means, develop a project for a dosage unit for reagents, a method for their introduction, and it is also necessary to organize the maintenance of a neutralization station.

All this requires significant costs not only for the preparation of waste for storage, but also for their long-term maintenance. Moreover, violation of storage protection with violation of environmental safety is not excluded.

The closest in technical essence is the method of purification of acid mine water, including the supply of acid mine water and a carbon-containing sorbent in the sodium form, mixing them to neutralize the water. The sorbent includes brown coal, sodium hydroxide and process water (patent No. 2319669, C02F 1/28, publ. March 20, 2008 - prototype).

The cleaning process is based on the fact that the transition of metal cations to an insoluble form occurs simultaneously with the sorption stage, insoluble metal salts are formed directly in the process of neutralization and are separated from acid mine water by precipitation of a carbon-containing sorbent in the sodium form with vigorous stirring. Spent sorbent containing metals is sent to the stage of thermal oxidation.

The cleaning method we have taken as a prototype is laborious and requires constant removal of the sorbed metal for thermal oxidation and, therefore, high costs for the purification of acid mine water and the preparation of the sorbent. In addition, the method does not eliminate the discharge of technological wastewater into water bodies.

The purpose of the invention is to increase the efficiency of the method while significantly reducing costs using a low-cost natural sorbent and to reduce the negative impact of weakly acidic metal-bearing quarry waters on the natural environment to ensure environmental safety of mining operations.

The technical result consists in transferring weakly acidic metal-bearing quarry waters of mining enterprises to weakly alkaline for interaction with peat of the lowland swamp. This allows you to reduce the cost of cleaning and the technological impact of mining on the environment.

The technical result of the invention is achieved in that a method of low-cost cleaning and disposal of mining wastes, mainly weakly acidic metal-bearing quarry waters in the conditions of bog-mountainous terrain, including neutralization, treatment and accumulation of waste by sorbents and their deposition, according to the invention, after neutralization with an alkaline reagent, weakly acidic career water is directed to the natural geochemical barrier of the bog-mountainous relief in the form of a peat deposit of a low-lying bog and use orff as a natural geochemical sorbent, while the metal salts of weakly acidic metal-bearing quarry waters are accumulated by the indicated natural sorbent and precipitated in the form of a complex insoluble organo-mineral material, and the formed permanent or temporary purified stream is directed according to the relief towards the stream or river, and the volume is preliminarily calculated discharge of slightly acidic quarry water, taking into account the sorption capacity of peat in lowland bog through the cation exchange capacity of peat relative to the capacity the cationic exchange of metal ions contained in quarry waters.

In addition, lime is used as an alkaline reagent.

A significant difference is that it is proposed to dispose and purify weakly acidic metal-bearing quarry waters in the peat deposits of the lowland swamp, which plays the role of a natural geochemical sorbent and has a high natural sorption capacity, at no additional cost.

This allows the use of significant and widespread deposits of lowland peat in the Urals region, that is, to use local resources of renewable raw materials, one of the few of which is peat.

The method of utilization and purification of weakly acidic metal-bearing pit waters into the peat deposits of the lowland swamp seems to be especially important from the geochemical point of view, since it helps to prevent the intensive migration of toxicants (metal salts) into natural systems in areas with an already high level of anthropogenic load, characteristic of the Ural region.

In addition, the use of a peat deposit in a low-lying swamp, which, being a natural sorbent with a very high sorption ability, actively accumulates metal salts, transforming them into a complex insoluble organo-mineral state, which reduces the geochemical mobility of hazardous substances and reduces the risk of environmental pollution .

The forming permanent or temporary already cleaned watercourse is directed, according to the relief, from the swamp towards a stream or river, it does not pollute surface water.

The method reduces the risk of environmental pollution and does not require additional costs for the treatment and disposal of metal-bearing quarry waters when dumped into a peat deposit of a low-lying swamp.

A significant difference is also that the method provides a preliminary volume of discharge of weakly acidic metal-bearing quarry waters, taking into account the sorption capacity of lowland bog peat through a cation exchange capacity, which indicates careful use of the natural environment and, therefore, reduction of the technogenic load on the natural environment in the long-term mode at no additional cost and at the same time cheapening the process of cleaning and disposal of quarry water.

In addition, the neutralization of a weakly acidic quarry solution with an alkaline reagent, such as lime, increases the pH of the discharged waters, increasing the sorption capacity of peat and increasing the swamp resource for long-term use of the existing quarry.

The analysis of the prior art by the applicant, including a search by patent and scientific and technical sources of information and identification of sources containing information about analogues of the claimed invention, allowed to establish that the applicant did not find a source characterized by features identical to all the essential features of the claimed invention. The definition from the list of identified analogues of the prototype, as the closest in the totality of the features of the analogue, made it possible to establish in the claimed method the set of essential distinguishing features set forth in the claims in relation to the technical result perceived by the applicant.

Therefore, the claimed invention meets the condition of "novelty."

To verify the compliance of the claimed invention with the condition "inventive step", the applicant conducted an additional search for known solutions in order to identify features that match the distinctive features of the claimed method from the prototype. The search results showed that the claimed invention does not follow explicitly from the prior art for the specialist, since the influence of the transformations provided for by the essential features of the claimed invention is not revealed from the prior art determined by the applicant to achieve a technical result.

Therefore, the claimed invention meets the condition of "inventive step".

The method is as follows.

A preliminary analysis of topogeological conditions and the selection of a storage area for the North-West section of the Volkovsky mine was carried out, the boundaries of the Chernovskoye lowland swamp were determined, which would be used as a natural geochemical barrier with its peat deposit as a natural sorbent for the treatment and disposal of weakly acidic metal-bearing quarry waters for the whole the term (approximately 20 years) of the Volkovsky mine:

- Chernovskoye swamp area - 0.513 km ² ,

- peat thickness (average) - 2.5 m,

- peat volume - 1.6 km ³ ,

- the weight of peat at a density of 1 t / m ³ (wet) - 1282500 t,

- The project term of the quarry is 20 years.

Laboratory work to determine the sorption parameters of peat within the lowlands of the Chernovskoye swamp of the North-Western section of the Volkovsky mine was carried out in the laboratory of physical and chemical analysis methods of the Ural State Mining University (certificate No.ROOC RU 0001. 517802, license No. Е04757, valid until March 14, 2013) with Considering the time-consuming use of the swamp for the treatment of discharged quarry waters.

The methodology for assessing the sorption parameters of peat by a laboratory method is described in the monograph: Bochever F.M., Lapshin N.N., Oradovskaya A.E. Groundwater protection against pollution. M. Nedra. 1979.

Installed:

Quarry water is a slightly acidic solution (pH 5.85) with a content (in mEq / dm ³ ) of copper 0.00094, zinc - 0.00066.

The exchange capacity for the selected humic substances in an acidic medium was 175 mEq / 100 g, the mass of humic substances was 3.89 × 10 ² g.

Calculation of the sorption capacity of peat in the lowland Chernovskoye bog through the cation exchange capacity:

N _total = N _gum. × m _gum ,

where N _total - the total capacity of the cation exchange of peat;

N _gum. - the capacity of the cation exchange of peat in the calculation of the content of humic substances in peat (mEq / 100 g);

m _gum - mass of humic substances in peat (g).

$$N_{\mathrm{about}bu.}=\frac{175\times 3.89\times {10}^{12}}{\mathrm{one\; hundred}}=6.81\times {10}^{12}mg-\mathrm{uh}\mathrm{to}\mathrm{at}.$$

The capacity of the cation exchange of peat relative to copper ions:

N _{for Cu} = N _total × m _equiv . _Cu = 6.81 × 10 ¹² × 32 = 2.18 × 10 ¹⁴ mg = 2.18 × 10 ⁵ T,

N _{by Zn} = N _total × m _equiv . _Zn = 6.81 × 10 ¹² × 36 = 2.45 × 10 ¹⁴ mg = 2.45 × 10 ⁵ T,

where m _{equiv. Cu} is the equivalent mass of copper ions;

m _{equiv. Zn} is the equivalent mass of zinc ions.

The results are presented in table 1.

Table 1 Ingredient The initial concentration in quarry water, mg / DM ³ Maximum sorption capacity (laboratory), mg / kg The residual sorption capacity of peat (shaft), mg / kg Actual concentration in peat (shaft), mg / kg Maximum sorption capacity of peat, kg Maximum residual capacity of peat, mg / kg Reset from
career
waters for 20 years, kg Average percentage
filling ingredient swamp containers Copper 0.06 250 169 80.88 (81) 390625 264,062.5 964.3 0.5% Zinc 1.19 300 266 323.98 (34) 468750 415,656.25 315.4 0.2%

Based on the above figures, the use of the Chernovskoye swamp as a natural purification system for the quarry waters of the North-West section of the Volkovsky mine is justified.

After calculating and determining the maximum sorption capacity of peat, they begin to drain quarry waters.

Initially, slightly acidic quarry waters are neutralized with an alkaline reagent - from lime - prepared with lime milk and the pH of the solution is adjusted to 7-8. After this, the water is sent through a pipeline to the natural geochemical barrier in the form of a peat deposit in the lowland Chernovsky swamp.

Example 1

The prototype method was tested in mine conditions when cleaning acid mine water having a pH of 2.7-3, Kizelovsky basin. For cleaning, we used a carbon-containing sorbent obtained from brown coals of the Berezovsky deposit of the South Ural coal basin in the mine waters of the Central mine of Chelyabinskugol Production Association.

As the sorbent used is an alkaline extract (humate solution) of brown coal (A ° - 7%), separated from the solid residue.

Insoluble metal salts of the carbon-containing sorbent were formed directly in the process of neutralization and separation of metals from acid mine water by precipitation of the sorbent with vigorous stirring.

The sorbent was isolated by filtration and centrifugation, and then it was sent to the stage of thermal oxidation, part of the mother liquor was used as circulating process water, and part was sent to a pond.

The results of the treatment of mine water from metal cations are presented in table 2.

Example 2

The slightly acidic quarry waters of the Northwestern part of the Volkovsky mine, contaminated with metal salts, were sent directly to the peat deposit of the Chernovskoye lowland swamp, which is a decrease in relief with a pronounced slope of the surface, in the direction of which a water stream formed.

Due to the natural high sorption capacity of peat (previously calculated and presented above), which plays the role of a natural geochemical barrier, metal salts precipitated from an aqueous solution in the form of a complex insoluble organic-mineral material.

The results of the treatment of quarry water from metal cations by the natural sorbent of the Chernovskoye bog are presented in table 2.

table 2 Ingredient Initial concentration, mg / l Example 1 Example 2 Concentration after purification, mg / l The degree of extraction,% Concentration after purification, mg / l The degree of extraction,% Cu 0.06 0,03 fifty traces ≈100 Zn 1.19 0.13 89 traces ≈100

The table shows that a high degree of extraction provides deep purification of quarry water to residual concentrations comparable to the maximum permissible concentrations (MPC).

The potential sorption capacity of the Chernovskoye bog with respect to copper and zinc is high, while experiments have shown that the sorption capacity of the peat of the lowland Chernovskoye bog can be increased several times by increasing the pH of the discharged waters to 7-8 and converting them from weakly acidic to slightly alkaline. This will increase the resource of the swamp and extend its use for many years to come, until the end of the career life cycle.

Thus, the goal is achieved by the fact that without any costly arrangement, the discharge of weakly acidic metal-bearing quarry waters into the peat deposits of the lowland marshes is organized, thereby reducing the cost of their disposal and treatment, and generally, the technogenic impact of mining on the environment is reduced without additional costs. natural environment.

In addition, the peat deposits of lowland marshes in the Urals are widespread and very significant. Therefore, in the interests of sustainable environmental and economic development of the region, the invention recommends the use of local peat deposits in lowland marshes, one of the few renewable types of minerals.

Claims (2)

1. A method of low-cost cleaning and disposal of mining waste, mainly weakly acidic metal-bearing quarry waters in a bog-mountainous terrain, including neutralization, treatment and accumulation of waste by sorbents and their deposition, characterized in that after neutralization with an alkaline reagent, weakly acidic quarry waters are sent to the natural geochemical the barrier of the bog-mountainous terrain in the form of a peat deposit of a low-lying bog and use peat as a natural geochemical sorbent, while meta salts Lows of weakly acidic metal-bearing quarry waters are accumulated with the indicated natural sorbent and precipitated in the form of a complex insoluble organic-mineral material, and the formed permanent or temporary purified stream is directed according to the relief towards the stream or river, and the sorption capacity of the natural sorbent through its cation exchange capacity relative to ions is previously calculated metals contained in quarry waters:
N _{by Me} = N _total × m _{equiv Me} mg
where N _{by Me} is the capacity of the natural sorbent relative to metal ions, mg;
m _{equiv Me} is the equivalent mass of metal ions;
N _total - the total capacity of the cation exchange according to the natural sorbent, mEq, determined by the formula
N _total = N _{gum. things.} × m _{gum. things.} mEq
N _{gum. things.} - the cation exchange capacity of the natural sorbent calculated on the content of humic substances in it (mEq / 100 g);
m _{gum. things.} - mass of humic substances in a natural sorbent, g. 2. The method according to p. 1, characterized in that lime is used as an alkaline reagent.