AUSCULTATION AND ZONE MONITORING OF CURRENT COLLECTOR OF THE KRIVELJ RIVER BELOW FLOTATION TAILING DUMP "VELIKI KRIVELJ", SERBIAMr Daniel Kranovi1, Miomir Miki1, dr Milenko Ljubojev11 Institute for Mining and Metallurgy Bor, Serbia

ABSTRACTFlotation tailings resulting in the production process of copper mining on the Veliki Krivelj is disposed in the tailing dump, which was established in the valley of the Krivelj river. To regulate the Krivelj river flow in the tailings area, was built the collector length of 2075 m. Due to the variations of designs, the collector has suffered serious damage, which requires constant monitoring of his condition.This paper describes the current state of collector under the flotation tailing dump Veliki Krivelj, based on monitoring program auscultation between June and December 2011. In the same period was performed, and monitoring water quality and air pollution at the site of flotation tailings Veliki Krivelj whose results are also presented.Keywords: auscultation, monitoring, collector of the Krivelj river, flotation tailing dump Veliki Krivelj.

INTRODUCTION

Near the open pit Veliki Krivelj, near Bor, is the Flotation tailing dump Veliki Krivelj, which has been in operation since the beginning of exploitation at the open pit. Flotation tailing dump Veliki Krivelj is a tailing dump of a valley type and occupies space in the former bed of the Krivelj River. Downstream of the tailing dump is the village Otrelj and upstream the belt conveyor system to waste transport from the open pit Veliki Kriveljs to the Old open pit in Bor and open pit Veliki Krivelj.Since the beginning of its work in 1982 until 1989, the Flotation plant Veliki Krivelj has dumped tailings in the old tailing dump - Field 1. Field 1 is formed by closing the valley of the Krivelj River by two dividing sand dams, an upstream dam 1 and downstream dam 2. For water evacuation of the Krivelj River, a tunnel was built through the rock massif with the route from the left bank of the original watercourse. The tunnel has diameter of 3 m, and its length is 1414 m.In 1990, the Flotation tailing dump Veliki Krivelj was extended downstream taking an additional space in the bed of the Krivelj River. Thus was formed a new tailing dump, which was called the Field 2. Construction of only one dam Dam 3 was enough for contouring the new tailing dump. For drainage the Krivelj River water, a collector, diameter of 3 m and 2075 m in length, which is a continuation of the existing tunnel, was constructed at the bottom of the Krivelj River.Considering that the current state of the collector is threatened, as it is shown in this work, and that overflow effects of the dam and collector destabilization are the ecological disasters of great proportions, a constant monitoring is necessary for the Flotation tailing dump dams and collector.The importance of such monitoring is enormous, both for the local population of the Bor municipality and population of neighboring countries in the Danube Basin, in which the Krivelj River flows.

1.0 STATE OF THE EXISTING COLLECTORProgram of monitoring the existing collector includes the monitoring of collector state by visual observation and measurements along the entire route of the collector. Visual observation monitors any changes on collector. Measuring monitors the temperature, flow rate of air, oxygen amount and concrete brand.1.1 Auscultation of the collector chainageThe complete collector is divided into chainages, which were repaired depending on the rehabilitation phase: with the phase of restoration: a stable outlet of the collector from chainage 0+0.00 to the chainage 0+200, rehabilitated part of the collector from chainage 0+200 to the chainage 0+903, from chainage 0+903 to the chainage 1+457 is the collector zone in which the first phase of rehabilitation was carried out by chainages 1+012 to 1+097 and 1+160 to 1+172, and chainage from 1+320 to 1+457, and the other parts to 2+026 is a zone which requires rehabilitation.The starting chainage of the Veliki Krivelj collector is below the dam Veliki Krivelj 3A, where the zero chainage is defined, Figure 1.

Figure 1 Start of the collector route below the Flotation dam 3A and Flotation tailing dump of the Field 2Damages were observed along the entire route of collector. These damages are manifested in the form of: breaking up of concrete to the reinforcement and large cracks, Figure 2a, concrete cracks in larger number of places, where the aggressive flotation water comes out under pressure, Figure 2b, chemism that occurs as the effect of aggressive flotation water and concrete, Figure 2c and large number of cracks through which, in addition to the water outflow under pressure, the chemism of this water occurs that sprays onto concrete.According to the visual observation of collector concrete, there are large number of aggressive water penetrations from the Flotation tailings, as well as chemism of aggressive water and concrete. Based on the measured concrete brand by sclerometre, it can be concluded that the concrete construction of collector is stable and secure in terms of functionality.

a)b)c)

Figure 2 - The appearance of concrete damages to the reinforcement in the side part of calotte (a), a set of cracks on the left side of campade through which water comes out under pressure (b) and chemism of concrete and aggressive water

The measureed values on the collector are given in Table 1. Table 1 The measureed values on the collector in the observed period Month

Flow rate of air, m/sOxygen amountO2 %TemperatureCConcrete brand MBMpa

June

July1.1021.015.8530/35

August1.7021.016.2030

September1.8220.815.8030

October1.8420.39.7030

November1.6720.17.5030

December1.1021.06.5030

Based on the analysis of parameters in Table 1, it can be concluded that the atmosphere condition in the observed part of collector is satisfactory, without occurrences of toxic gases that would have a negative impact on human health.

2. PROGRAM OF MONITORING THE WATER AND AIR QUALITY Program of monitoring the water and air quality was done six months from June to December 2011.

2.1. Program of monitoring the water quality Water quality monitoring program includes weekly and monthly monitoring of groundwater and surface water. Surface water quality monitoring was conducted at 8 measuring points as follows: water of the Saraka stream (MM[footnoteRef:1]*-1), the Krivelj River before inflow into Saraka stream (MM-2), the Krivelj River before inflow into Saraka stream (MM-3), the Bor River below Dam 1 (prior entering into collector) (MM-4), the Krivelj River below Dam 3 of the Flotation tailing dump Veliki Krivelj (MM-5), the Bor River before connecting with the Krivelj River (MM-6), the Krivelj River before inflow into the Bor River (MM-7), water after connecting of the Bor River with the Krivelj River and pit water (MM-8). [1: * Measuring point]

In order to monitor the groundwater quality in the vicinity of watercourses of the Krivelj River, three piezometers were placed in three different locations, several kilometers apart. Monitoring of these waters was done on a monthly basis.Monitoring the following parameters was done at shown measuring points: weekly monitoring of pH, temperature (air and water), conductivity, soluble oxygen, monthly monitoring: pH, temperature (air and water), conductivity, soluble oxygen, flow, suspended particles, sulfate ion and ions of toxic elements - copper, lead, zinc, cadmium, nickel, chromium, selenium and arsenic.Water pH value was measured by ICP method, while the Standard SRPS EN ISO 11885 was used for measuring the concentration of metals in water.

2.1.1. Results of monitoring the water qualityResults of monitoring the water quality are shown in Table 2. Table 2 Results of monitoring the water qualityMeasuring pointPeriod

SummerWinter

pH valueCopper concentration (mg/dm3)pH valueCopper concentration (mg/dm3)

MM-16.530.10 5.414.70143.00 173.00

MM-27.500.10 20.835.002.00 55.00

MM-37.00 7.80.107.00 7.8032.30

MM-45.0012.50 21.606.247.10 23.80

MM-53.266.30 38.507.0010.90 19.20

MM-64.93 5.3013.20 18.504.93 5.3019.80 34.50

MM-75.52 5.998.505.52 5.9920.30 25.10

MM-82.10 3.36185.002.10 3.3668.90 119.00

Ground water quality was determined on the basis of measuring on piezometers P3, P4 and P5Water in piezometers P3 and P5 wasconstantly of slightly acidic character, pH ranged from 6.7 to 7. Copper concentrations in water were in the range of 4.5 to 20.9 mg/dm3, noting that the concentration increased during winter period.Water in piezometer P4 was constantly of acidic character, pH ranged from 4.1 to 4.9. Copper concentrations in water were consistently increased from low content in summer periods from 0.05 mg/dm3 to the increased concentrations in winter period to 96.2 mg/dm3.2.2. Program of monitoring the air qualityAir quality monitoring program includes daily measurements of air temperature, humidity, precipitation, atmospheric pressure, wind speed. Monitoring of air quality (sediment matter) is done at 6 measuring points: above the Saraka landfills, above Field 2 of the Flotation tailing dump Veliki Krivelj, above Dam 3 (village Otrelj), below Dam 3 (Manastirite), local community Sloga and village Slatina.

2.2.1. Results of meteorological observationsIn summer period, mean monthly values of temperature were varied in the range of 11.6C to 26.5C. The values of relative humidity were in the range of 35% to 80%. Atmospheric pressure ranged from 964.2 mbar to 982.2 mbar. Total amount of precipitation was on average about 19 mm/m2. Prevailing wind direction was from WNW. Mean wind speeds ranged from 0 m/s to 2.9 m/s.In winter period, mean monthly temperature values were ranged from -4.3C to 19.5C. Values of relative humidity were in the range of 34% to 100%. Atmospheric pressure ranged from 949.7 mbar to 990.8 mbar. Total amount of precipitation was on average about 20 mm/m2. Prevailing wind direction was from WNW. Mean wind speed ranged from 0 m/s to 2.6 m/s.

3. AUSCULTATION VISUAL OBSERVATION OF THE FLOTATION TAILING DUMPS In the area of the Flotation tailing dump Veliki Krivelj, the observation - auscultation was carried out in the period June-December 2011. The goal of these observations is monitoring the movements and deformations of all objects on this site. Auscultation was performed at the following locations: Field 1 and Field 2, as well as Dams 1A, 2A and 3A of the Flotation tailings dump.

3.1. Auscultation of the Flotation tailing dympVeliki KriveljDam 1ATailing dump Veliki Krivelj consists of two fields: Field 1 is limited by upstream Dam 1A and downstream Dam 2A, and Field 2, which is limited by upstream Dam 2a and downstream Dam 3A (Figure 3).

a) b)

Slika 3 - Flotacijsko jalovite Veliki Krivelj (a - Jun 2011, b) decembar 2011.)Monitoring the condition of Dam 1 and Field 1 in the period from June to December 2011 has resulted into several conclusions.At the beginning of recording the situation, it was concluded that there was an increase of seepage water and newly-formed springs through the body of Dam 1. This negatively affects both the stability of dam itself and additional pollution of the Krivelj River flow. Therefore, the constant monitoring of seepage water levels was adopted in the piezometers as well as pH value, chemical composition and content of sand particles in the leachate sources.Analyzing the last state (December 2011) - a developed geometry of dam, it was observed that the crown of dam took the position that there should be at the end of the project, when it would reach the design level K +385 m of altitude.The formed storage lake in Field 1 has several times larger surface area and volume than the technology of dumping and processing requires in the Krivelj Flotation, i.e. it deviates significantly from design contour of the precipitation lake. Elevation of the storage lake in Field 1 is 359.80 m altitude, which directly leads to the increased depth of the storage lake near Floating Pump Station (FPS), so that it is about 3.8 meters.Reducing the level of storage lake will directly reduce the inflow of seepage water as well as its level in the installed piezometers. This directly increases the coefficient of Dam 1A stability, which is at present close to the limit value.Some parts of dam are not reclamated. Due to the effects of wind and water in these places, there is erosion, resulting in ravines that affect the dam stability. Dam 2ASand dam 2A limits the Field 1 with a downstream side in the direction of inactive Field 2. The position and geometry of Dam 2A is shown in Figure 4.

Figure 4 - Dam 2A of the Flotation tailing dump Veliki Krivelj view from the road, December 2011

In the observed period June-December 2011, several conclusions were derived by auscultation: Super elevation of Dam 2A was constantly progressed by identical geometry in the observed period, The resulting discrepancies between the designed and constructed geometry of Dam 2A geometry, but they are far smaller than on Dam 1A, In the observed period, seepage water extended the front. The appearance of this water further destabilizes Dam 2A which is up to this point in far better condition than Dam 1A.

Dam 3ADam 3 is the ending downstream dam, which limits Field 2 from downstream side in direction of the village Otrelj. As it can be seen from Figure 5, this dam is eroded in its large part, especially its crown, so that its height in many places is below 345 m altitude.Since the water elevation in the storage space is 349.60 m altitude, the severity of current situation is great. As the result, monitoring was performed continuously on Dam 3A crown and its outer slope. In this way, it can be affected due to the negative impacts of this tailing dump on the village Otrelj, located downstream from Dam 3A.

Figure 5 Erosion effect on Dam 3A, June 2011

4. CONCLUSIONFlotation tailing dump present the constant danger to the ecological factors of environment whether they are in operation, or after cessation of tailing disposal and filling the landfill space. Due to this reason, it is necessary to fully utilize the disposal space that does not take up the new areas and pollute the new river flows.This paper presents the auscultation of dams of the Flotation tailing dump and chainages of collector and monitoring the water quality. Based on the presented situation and measuring results, it can be concluded that there is a problem of preservation the Flotation tailing dump in operation.For maximum usage the existing landfill space, it is needed to upgrade the Dam 3 of the Flotation tailing dump Veliki Krivelj. For that purpose, a tunnel will be constructed under Field 2 to drain water of the Krivelj River instead of the current collector, which requires large financial resources for rehabilitation the damaged part. Thus, the possibility of accident will be reduced.

ACKNOWLEDGEMENT

This work has resulted from the Project No. TR33021, funded by the Ministry of Science and Technological Development of the Republic of Serbia.REFERENCES

1. M. Ljubojev, D. Ignjatovi, L. Djurdjevac Ignjatovi, V. Ljubojev, Preparations for Investigation the Tunnel Route and Field Surveying, Mining Engineering Journal, No. 1, 2011, pp. 135-166.2. S.Krsti, M.Ljubojev, M.Miki, V.Ljubojev: ,,Methods of geotechnical investigations for rehabilitation and remediation the flotation tailing dump Veliki Krivelj (Serbia). XIV Balkan mineral processing congress, proceedings, Jun,2011, Tuzla, BIH (851-853).3. Slaana Krsti, Miomir Miki, Milenko Ljubojev, Omer Musi, Vesna Ljubojev:,,Conditions of drainage of flotaion tailing of "Veliki Krivelj. 43rd International october conference on mining and metallurgy, proceedings, Octobar 2011, Kladovo, Srbija. (221-238)4. Miomir Miki, Daniel Kranovi, Slaana Krsti: ,,Overview of the current situation of major facilities of the flotation tailing dump Veliki Krivelj near Bor with special review to the collector of the Krivelj River. 43rd International october conference on mining and metallurgy, proceedings, Octobar 2011, Kladovo, Srbija. (303-306)5. Daniel Kranovi, Miomir Miki, M.Ljubojev:,,Analysis the spatial position of mining facilities of the Veliki Krivelj mine to the proposed tunnel route for relocation the Krivelj River. Mining engineering 3/2011, 2011. (95-100)6. Daniel Kranovi, Miomir Miki, M.Ljubojev: ,, Analysis of development effects of the Veliki Krivelj mine on construction the new facilities for deviation the Krivelj River. Mining engineering 4/2011, 2011. (57-65)7. S.Krsti, R.Lekovski, M.Miki: ,, Environmental protection from dust from flotation tailings Veliki Krivelj. Air protection 2011, proceedings, Zrenjanin Hotel Vojvodina 7.-9.11. 2011. (200-206).