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Examples of Impacts on the Geological Environment of Cyprus

 

Two examples of the serious impacts that the exploitation and processing of mineral deposits had on the environment in Cyprus are given below.

 

The first example comes from the site of the sulphide processing plant at Xeros. It reveals that the pollution of the soil, the groundwater and the sea in the area is from toxic acid waters and base metals, which were released during the processing of the sulphide ore. The concerns of the people living in the area are conveyed below and possible mitigation measures to minimise the effects on the environment and the people are suggested.

 

The second example comes from the asbestos mine at Pano Amiantos on the Troodos Range. The impacts on the environment and the people from the mining and processing of asbestos are defined below and the restoration measures that have been taken are described. The beneficial results of these measures are already obvious.

 

4.1.  Environmental Impacts of the Sulphide Ore Treatment Activities at the Ore-Dressing Plant in the Lefka-Xeros Area

 

4.1.1. Site Description and Observations of the Area

The sulphide ore-dressing plant operated in the Xeros-Lefka area at a short distance from the coast of Morphou Bay between 1916 and 1974. It is situated to the north of Skouriotissa, Lefka and Apliki and to the north-west of Peristeronari. On the coast to the west of the plant lies Karavostasi from where ore had been exported since ancient times. The area of the plant has an altitude slightly above sea-level but this increases gradually further inland and reaches 300 m at Mavrovouni Hill on the Troodos foothills.

 

The Lefka, Karyotis and Xeros rivers traverse the area from south to north.  They originate from the Troodos Mountains and flow into Morphou Bay. The main water resources in these rivers are surface water and groundwater from the riverbed alluvial aquifers with sediments reaching 45 m. Lefka and its vicinity are the most replenishing areas in this part of Cyprus.  A deviation channel was built at the beginning of the 1980s and was connected by three regulators to the Xeros, Lefka and Karyotis rivers for collecting the surface flows of these rivers. 

           

Palm trees, olive trees and citrus trees are the dominant agricultural plants in the area.  The main income in this region is agriculture and tourism.

           

The abandoned ore residues, ore processing remnants and chemical materials are the sources of contamination in the area. These contaminated materials are easily seen on entering the Xeros area, as for instance are the remnants of low-grade ore and the cyanide gold processing remnants. At the upper flanks of the Xeros River, residues of ore extracts have affected the whole area. Today, the contaminated lands have jeopardised local residents’ health as well as that of the future generations. They wonder what measures will be taken to clean up the area. This environmental problem of contaminated land has been around since 1913 and nothing has been done since 1974, when operations in the area ceased.

 

4.1.2.   Geology

The main geological units in the Lefka – Xeros area are divided as follows: 

  • Upper Cretaceous (Lower and Upper Pillow lavas);

  • Upper Miocene reef limestones (Koronia Formation) and massive gypsum deposits of Kalavasos Formation, which were deposited during the Messinian salinity crisis;

  • Pliocene Marl Formation incorporating marl, biocalcaranite, sandstone, silt, gravel, sandy marl, and conglomerate;

  • Pleistocene fluvial deposits bearing gravels and boulders that were derived from the Troodos Mountains;

  • Recent deposits, river and beach deposits.

 

4.1.3.   Mineralisation

The volcanic rocks (Upper and Lower Pillow Lavas) are of considerable importance for geology and the economy, and the Troodos Ophiolite in general is considered as one of the best known examples of well preserved pieces of upper mantle and oceanic crust in this region of the Earth. The economic aspect of mineralisation is based mainly on sulphide ore-bodies as well as other associated mineralisations.

 

The Troodos Ophiolite complex formed approximately 92 Ma beneath the ocean floor. Detailed geological, geochemical and mineralogical studies show that the sulphide ore deposits of Cyprus formed along mid-oceanic ridges and are known as “Cyprus type deposits”. The formation of these deposits was due to the circulation of hydrothermal solutions rich in metals. According to this mode of formation, seawater that is heated and chemically modified by leaching metals and other elements from the rocks with which it came into contact enters the oceanic crust in the vicinity of spreading centres and exits at focussed discharge sites on the ocean floor as metal-laden hydrothermal fluid. The exit sites mark the location of the sulphide deposits.

 

The cupriferous sulphide deposits that have been worked on in Cyprus are found in six mining districts: 

  • Skouriotissa–Mavrovounni–Apliki

  • Tamasos (Agrokipia-Mitsero) 

  • Kalavasos

  • Limni

  • Kampia–Kapedhes

  • Sia-Mathiatis.

 

4.1.4.   The History of Mining Activities in the Lefka-Xeros Area

It is known that copper mining in Cyprus has been carried out since ancient times. The island’s main mining product became known as “Chalkos Kuprios”, a term changed by the Romans to “aes Cyprium” or “aes Cuprum”, signifying “the Metal of Cyprus”. Later modification resulted in the chemical symbol “Cu” and the English word of copper (Lavender, 1962).

 

4.1.4.1   Ancient Mining Period 

  • Chalcolithic Age (BC 3500-2500) - mining and processing activities have been taking place in the Lefka-Xeros area since this period (Constantinou, 1992).

  •  Bronze Age (BC 1350) - Phoenicians produced copper during this period. Slugs discovered at Apliki are remnants of these activities (Lavender, 1962).

  • Kingdom of Soli (BC 575) - Well-developed mining and smelting processes were carried out during this period in the ancient city of Soli, which is located near Lefka (Lavender 1962).

  • Roman Period (BC 58 – AD 330) - The slugs located near major mineral deposits at Mavrovouni and Skouriotissa are the most prominent evidence of Roman ore extractions (Spyridakis, 1964).

 

4.1.4.2.   Mining of Modern Times

 

Copper production with modern technology in the Lefka area was carried out between 1913-1974. The production of ore started  in 1921 at Skourotissa, at Mavrovouni in 1929 and at Apliki in 1960. A considerable portion of high-grade ore produced was exported as crude ore. In 1930,  a treatment plant was established in the Xeros area and started processing copper concentrates, cement-copper and pyrites in the period of 1931-1940. The main focus was on the production of gold due to its high price on the world market, while there was a drop in the production of cupriferous pyrite. A cyanide processing plant was built for gold production in the Xeros area and unprocessed ore was also shipped from Phoukassa (Devils Mud) and Mathiatis. This plant was dismantled after World War II. These residues are visible at the entrance of Xeros, immediately opposite the old port, as yellow coloured rectangular heaps.

 

4.1.5.   Remaining Ore Bodies

  • Skouriotissa

These ore bodies are situated in the Phoukassa, Tree Hill and Phoenix areas. After the extraction and processing of large amounts of ore in the years 1921 – 1974, there are still 67 million tonnes of ore left behind.  The high-grade ore with a copper content of over 0.4%, and the low-grade ore with a copper content below 0.4% are included in these estimates (Hellenic Copper Mines records).

Since 1996 Hellenic Copper Mines Company has been applying a copper processing method employing hydrometallurgical processing technology.

  • Apliki

The mine was worked in the period 1960-1974. It seems that another 23 million tonnes of ore remain.

  • Mavrovouni

The profitable ore body was exploited in the period 1929-1970. There are still 11,300000 tonnes of low-grade ore and 250,000 tonnes of high grade ore which could not be extracted economically as it occurred at a depth of 250 ft below sea level.

  • Lefka A

Lefka A is situated at a higher altitude than the Mavrovouni ore-body and was exploited by open-cast  mining. The first phase of operation was completed in the period 1960 - 1973. There are still 730,000 tonnes of high-grade ore, which was planned to be extracted at a second phase.

  • Lefka E

The exploration phase was completed between 1966 and 1970 but the operational stage has not happened, because the ore body was located beneath a residential area. The total amount of ore was estimated at 1,127,000 tonnes 

  • Dumps

These contain materials that were excavated during mining but could not be processed profitably in the existing treatment plant. Approximately 2,000,000 tonnes of low-grade ore were dumped on the western slopes of Mavrovouni.

 

4.1.6.   Metallurgical Process

 

The Treatment Plant at Xeros was designed for the Leaching – Precipitation – Flotation process (LPF):

 

Crude Ore → {0.6–1.0% Cu – 25-30%S}

                                           

                                       Crushing

                                            

Acid additives  → Leaching → Precipitation → Cement Copper (over 95% Cu)

                                                                                             (1)

                                      Grinding

                                            

Rougher Flotation → Tails ← Mining Chemicals

                                                                   

                                     Concentrate        Flotation    → Acid Tails

                                                                                       (4)

 

       Basic Tails ← Cleaner Flotation     Pyrite Concentrate  (over 46% S)

             (5)                                                      (3)

                             Copper Concentrate  

                                (over 15% Cu)

                                          (2)

 

From the simplified flow sheet above, it is seen that five different types of materials were produced:

  • No. 1 and 2 products were exported;

  • No. 3 product – a small portion was used in the existing weak acid oxidation process to produce acid for leaching at the site. The rest of the portion was exported.

  • No. 4 and 5 products were deposited separately in twelve Tailing Ponds located in the coastal area of Xeros.

 

4.1.7.   Tailing Ponds

 

Tailing ponds occupy an area of approximately 750,000 m2 including the processing plant, while the estimated total area of land is 1,560,000 m2.

 

According to drilling studies carried out in 2003 , it was estimated that 7 million tonnes of tailing material had accumulated in these ponds

 

The average metallic content results from the tailing ponds are given below: 

  • Copper (Cu): 0,2 – 0,63%

  • Cobalt (Co): 70 – 450 g / tonne

  • Gold (Au): 0,2 – 1,0 g / tonne

  • Nickel (Ni): 20 – 55 g / tonne

  • Vanadium (V): 150 – 300 g / tonne

  • Molybdenum (Mo): 20 – 120 g / tonne

 (Ref: Doba Invesment Ltd. Reports)

 

According to analyses carried out recently, the metallic content of tailings increases in the deeper parts of these ponds. This may be the result of long term, natural leaching, which is due to the penetration of pregnant solutions through the deeper parts of these tailing ponds.

 

Sieve analysis of the tailing material showed that 75% of tailing material had a particle size smaller than 38μ.

 

4.1.8.   Environmental Effects of Tailings

4.1.8.1.   Chemical Activity

Tailing ponds contain sufficient amounts of iron, copper, and sulphur as well as other metals, which have the potential to create acidic compounds under natural conditions.

 

Production of sulphuric acid, iron hydroxide and other metal salts can be summarised as a reaction process as given below:

 

A)   4FeS2 + 15O2 + 14H2O → 8H2SO4 + 4 Fe(OH)3

B)   2CuFeS2 + 16H2O → 2Cu2+ + 2Fe2+ + 4SO42- + 16H2

 

These and other more complicated reactions are dependent on precipitation, heat and other natural factors. The products of each reaction are potential sources of environmental degradation.

Pregnant-solutions penetrate underground or flow to the sea during floods and as a result soil and ground water quality deteriorates.

 

In winter, accumulated liquids of reddish–brown colour are observed on the surface. This represents iron hydroxide, which is the product of acid – sulphide reaction.  In summer, yellowish-brown coloured precipitation is observed due to the evaporation of the pregnant liquid. This represents copper–iron salts, locally known as “Galangati”.  Likewise, in summertime a sulphur smell, spreading in the air is evidence of chemical activity in sulphur bearing accumulations.

 

4.1.8.2.    Drainage and Stability

 

The berms and drainage structures of the tailing ponds are designed as shown in the sketch.

Over a long period of time, without any remediation, the drainage–pipes become blocked and surface water accumulates on the pond surface, which affects the berm stability.  With intense rainfall flooding occurs over the berms and as a result tailing material spreads around. This creates serious concerns for the residents.

 

4.1.9.    Other Potential Contaminants

4.1.9.1.    Ruins Around the Old Processing Area

Ruins that appeared in the last 30 years around the abandoned Treatment Plant, Old Mining Reagents, Gold Cyanisation Tailings (about 150 000 tons), and Iron oxides (Roasted – Pyrite tailings) are potential sources of pollution.

 

4.1.9.2.    Low Grade Ore Dumps

Approximately 2 million tonnes of low-grade ore (Cu content < 0.4%), which were dumped during operation times between the Xeros reservoir and the western slopes of Mavrovouni, risk polluting the water in the reservoir that was built between 1991 - 1993. 

The dumped material covers an area of about 15,000 m2. Natural leaching occurs during rainy seasons and pregnant solutions mix with the reservoir water.

 

The reservoir was constructed in 1990 and can hold 4 million m3 of water. It is used for irrigation and the boreholes located at the southern end of the reservoir supply drinking water. 

Due to the contamination risk, TCC geology and water authorities are examining the heavy–metal contents regularly.

 

4.1.10.    Possible Mitigation Measures

 The residents of the Lefka – Xeros and Karavostasi areas are concerned about contamination due to the old mining activities and the fact that problems will continue due to these tailings as long as no remedial measures are taken.  After a long discussion, some short-term and long-term measures were proposed. This task was undertaken by Doba Investment Ltd. in 2003.

           

As a result of this project, the following temporary measures are in place: 

  • Fencing and attention signs were hung up at the entrance of the tailing area;

  • Burying of mining reagents (approx.350 barrels)                

  • Circulation of pregnant solution into previous order, and prevention from flowing into the sea.

The Company is still working towards the following permanent measures depending on which is more economic: 

  • sealing up the tailing ponds;

  • reprocessing tailing ponds material to gain economic values and transport all of the tailing materials into a new site.  

 

4.1.11.    Conclusions

The mining activities were a source of income for local residents for a long period of time. However, nowadays they worry about their future as the mining activities are interfering with many things they use in their daily lives.

                       

 4.2.   The Asbestos Mine

 The island of Cyprus ranks as one of the most ancient sources of asbestos, and deposits of this non-metallic mineral were known and exploited by the ancient Greeks and the Romans. In modern times, mining of asbestos began at Amiantos in 1904 and Cyprus gradually became important in possessing one of the biggest occurrences of chrysotile asbestos in Europe. Mining continued uninterrupted until 1981, but from 1982 onwards economic problems caused by the fall of the prices of asbestos, in conjunction with the serious environmental and health problems that arose, led to the definite termination of all mining activity in 1988 and the withdrawal of the mining lease in 1992. The most common asbestos mineral occurring in Cyprus is chrysotile (Photo E9). It is a fibrous mineral, which formed during the serpentinisation of the harzburgite, and is confined to an area roughly oval in shape and of approximately 13 km², near the village of Pano Amiantos on the eastern slopes of the ultrabasic mass, at an altitude of 1,500 m.

 

As the mining of asbestos was near surface, an area of 3.3 km² was affected and turned into derelict land (Photo E10). In total, more than 130 million tonnes of rock were extracted for the production of one million tonnes of asbestos fibres. The rock waste from the quarries and the processing mills was placed in huge dumps without much concern for the environment or for the safety of the village of Kato Amiantos right below.

 

The negative impacts on the environment from the operation of the asbestos mine for more than 80 years have been manifold and mainly include the following:

a) total destruction of all the natural forms of the landscape over the entire area of the mine;

b) formation of huge waste dumps in forms and shapes strange to the local environment. Apart from their environmental impact, the instability of these dumps increased the risk for landslides and mass movements putting the areas below in great danger;

c) pollution of the ground of the mine and the surrounding area with loose asbestos fibres that could be transported easily by the wind to the atmosphere, as well as of the surface waters for a long distance downstream of the mine.

 

A possible positive impact of mining asbestos for more than 80 years is the great economic gains that benefited  Cyprus and its inhabitants. When the exploitation of this natural resource began in 1904 it provided jobs to thousands of Cypriots and contributed substantially to the economic and social growth of the island.

 

4.2.1.   Restoration of the Environment

 

The lack of any legislation during the period of operation of the asbestos mine did not compel the mining companies to take any measures for the restoration of the environment. When the mining lease was cancelled in 1992, and in view of the great impacts of the mining activities on the environment and the people, the authorities undertook the task of restoration. Restoration works began in the autumn of 1995 and according to a restoration plan the principal targets were the following:

a)  stabilisation of the waste dumps (Photo E11);

b)  reformation of the disturbed surfaces (Photo E12) according to the originally prevailing relief;

c)  enrichment of the newly established barren ground surface with fertile soil (Photo E13) transported from elsewhere;

d)  planting of trees and bushes (Photos E14, E15) and generally covering the whole of the area with vegetation.

 

According to the time schedule of the restoration plan the works for the stabilisation of the waste dumps and the reformation of the area will be completed by 2005, while planting and reforestation will be finished by 2015. The beneficial results of the restoration works are already evident but it will no doubt take a few more decades before the impacts on the geological and natural environment in general are minimised and the affected area is back to a more natural state.

 

The restoration works that are carried out at the asbestos mine could probably form an example and a model for similar works that have to be carried out at the tens of disused and abandoned sulphide mines, which have similarly caused great destruction to the environment. The cost is very high but the benefit to the environment and mankind will compensate for that.

 

 

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