The current mining industry is under big pressure, especially because of the many serious environmental problems generated by the storage and management of the waste, resulted from technological processes of extraction and preparation.
The adequate management of this mining waste represents one of the greatest challenges of the mining industry, both through the high costs needed for maneuvering and storage, and through the great impact and environmental risks that are generated.
The management of mining waste in Cupru Min represents a set of activities which have the same goal, which is reducing environmental pollution, generated by the mining waste deposits.
Taking into consideration the fact that the exploitation and preparation of ore in Rosia Poieni are realized on a large scale (over 2.000.000t mining mass/year), the maneuvering, storage and management of the quantities of the generated waste, is one of our biggest challenges our society deals with, in order to diminish the negative effects on the environment.
According to the 5th Article from Directive 2006/21/CE of the European Parliament and according to the Council’s meeting on 15th March 2006, regarding waste management in extractive industries, our society has written a “Waste Management in Extractive Industry Plan”, having the following objectives:
- Reducing waste generation
- Encouraging the fructification of extractive waste, where this activity is viable.
- Surveillance, control and management of waste installations
- The safe discharge of waste, long-term and short-term, so that when the activity stops, all the pollution risks are avoided, and the emplacement is brought to a satisfactory state, so that it is used in the economic circuit.
According to the specifications of the 3rd annex of HG 856/2008 and to Decision 2009/337/CE from April, 23rd, 2009 regarding the definition of classification criteria of waste management according to the 3rd annex of Directive 2006/21/CE of the European Parliament and according to the Council’s waste management in the extracting industry, the waste deposits in Rosia Poieni are not type A installations.
We mention the fact that all these waste deposits are NONSEVESO installations.
Sesei Valley pond is the main functioning pond of S.C. Cupru Min S.A. Abrud, being, at the same time, the biggest pond of Romania. The pond is situated on Lupsa’s territory, Geamana village. Due to its construction, it is a valley pond, formed by barring Sesei Valley with a rockfill dam, with a filter mask on the upstream river, which is situated 7.2 km distance from Valley Sesei’s confluence with Aries river. The construction and exploitation of this pond follows all the technical rules regarding the hydro technical works of this type.
The floatation tailing comes up as a soft ground solid, with sandy particles, having a density of 2.3-2.5 kg/dm3 , which are water-insoluble, physically and chemically stable, in normal storage conditions. The floatation tailing transportation from the preparation plant to the pond is hydro-gravitational made, at a dilution of 2.25/1 L/S, the pond having the role of a decantation pool.
The field on which this pond is located is the property of S.C. CUPRU MIN S.A. From the beginning of the construction works, the owners of the fields were expropriated and rewarded according to the legislation from that time. The expropriated area considered the construction of the lake up to 710m, this representing a surface of 221ha. Upstream Sesei Pond Valley, there are the tailing dumps from Rosia Poieni Quarry.
The company keeps under control the action of acid water of
the rocks, which solubilize the heavy metals from the tailing dumps, and reduces their impact on the surface water’ quality through treatment, using chalk milk liquor 3-10%.
The “porphyry copper” deposits, as that from Rosia Poieni is, have an essential characteristic – the pyrites and the copper minerals are softly spread in the whole deposits’ body.
As time passes, making contact with the air and in the presence of humidity, the ore and the quarry dumps have an acidophilic character. The water that cross the tailing dumps become acid and strongly mineralized, so that the “mine water” are formed, as a result of the natural process of biochemical oxidative leaching.
Therefore, in Sesei Valley pond, located downstream the tailing dumps, get the debris coming from the preparation plant (having a basic pH, from 10 to 12), local neutral water and acid water coming from the tailing dumps with acid pH (~1.5-2.8), and with high heavy metals concentration.
In order to realize their neutralization, BAT technique is used, according to BREF reference documents regarding the best available techniques for tailing and residual sediments of mining activities Management, to treat the acid effluents (section 18.104.22.168), and the active treatment adding hydrated lime or slack lime.
To pursue the quality indicators and to respect the maximum accepted values, Cupru Min oversees (during the working days) both the quality of the evacuated water from Sesei Valley pond in Aries river and the quality of the water from Aries river, upstream and downstream the confluence with Sesei Valley.
ENVIRONMENTAL RISKS MANAGEMENT
The main environmental issue of our society is the acid water leakages, which come from the tailing dumps and which solubilize heavy metals, but also their impact on the quality of surface water.
In Sesei Valley Pond, situated downstream the tailing dumps, gets all the debris that comes from the preparation plant, which has a high basic pH (10-12), the neutral water from that area and the acid water from the tailing dumps with acid pH (1.5-2.8) and high concentrates of heavy metals.
In 2017, Cupru Min S.A. Abrud solved its environmental issues:
1. The additional closure of the former gallery which evacuated reverse probes for better safety in the functioning of Sisei Valley decantation pond. – accomplished achievement
2. Until the installation of purge/neutralization of acid water is realized (the solution accepted by APM Alba, instead of metal recovery installation), the neutralization of acid water that came from the tailing dumps is made by adding calcimine 3-10%, a liquor prepared at Dealul Piciorului preparation plant and gravitationally transported in pipes to acid water areas. Due to lime neutralization, the bio-chemical processes are stopped, and the evacuated water from Sisei Valley fits the limits imposed by the authorities.
3. Gathering the water of the tailing dumps, in order to assure the stability of the dumps. In November 2017, an auction for the accomplishment of works took place, but due to the lack of the construction authorization, the contract to fulfil the works hasn’t been signed.