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2.1 Aluminium extraction
2.2 Heavy metal ore smelting
2.3 Secondary smelting plants
2.4 Non-ferrous metal semifinishing works

3. Notes on the analysis and evaluation of environmental impacts

4. Interaction with other sectors

5. Summary assessment of environmental relevance

6. References

Statutory provisions, regulations
Scientific/technical papers

1. Scope

Since the non-ferrous metals sector covers a multitude of individual products, charge materials, fuels and processes, this brief can only deal with a few examples of the principal industrial non-ferrous metals. Environmental impacts and protection measures in the production and processing of aluminium, copper, lead and zinc are dealt with as representative of the large number of other non-ferrous metals as well.

The non-ferrous metals sector comprises the subdivisions:

- smelting of appropriately pretreated primary raw metals to produce metals
- processing recycling material in secondary smelting plants, and
- processing of metals to produce standard commercial billets and blanks.

2. Environmental impacts and protective measures

The following deals primarily with the environmental factors arising in the application of current standard processes. For projects using pyrometallurgical processes these are primarily air protection measures; slags are also produced which, depending on their composition, can be a danger to soil, water and living things. In hydrometallurgical treatment processes, measures to protect water and soil predominate.

Since most processes generate noise, the possibility of noise pollution occurring both in the work-place and in the neighbourhood must be taken into account.

Non-ferrous metal production plants occupy a considerable amount of space to accommodate the works site with adjoining areas and connecting roads.

Different quantities of energy are required depending on the production process. The choice of location partly depends on the availability of sufficient low-cost electricity, e.g. in the case of aluminium production. An encapsulated furnace producing aluminium by igneous electrolysis, with a current load of 200 kA and d.c. voltage of 4.2 V requires approximately 13 kWh/kg aluminium. Zinc production with the stages of roasting, leaching, neutralization, leachate cleaning and electrolysis requires 4 kWh/kg zinc. Values for copper production are somewhat higher. Energy requirements of secondary smelting plants are considerably lower: 20% of the primary smelting energy requirement with 100% scrap copper, around 40% with 100% scrap zinc and 10% with 100% scrap aluminium.

2.1 Aluminium extraction

The Bayer process is used almost exclusively for producing aluminium oxide, the charge material for primary aluminium smelting plants. Bauxite is treated with soda lye under pressure and heat in autoclaves to produce aluminium hydroxide and red mud. The latter is separated, washed and filtered, and may be recyclable or may have to be dumped. After sedimentation and filtration, the aluminium hydroxide is converted to aluminium oxide (alumina) by fluidized bed calcination at around 1100°C.

Large quantities of red mud (1 - 2 t/d Al₂O₃) are produced. Depending on its composition and the situation in the country in question, it should be used for extracting aluminium oxide and iron, producing flocculation agents for wastewater cleaning or the manufacture of building materials. Red mud which cannot be further processed must be dumped. Where it is stored on a dump, special requirements must be met in respect of sealing and treatment of percolation water. Dumping should be on a single-purpose dump subject to continuous supervision.

A considerable amount of fine dust may be produced upon loading, unloading and transport of fine-grained materials (bauxite, alumina) unless enclosed conveyor systems and suitable storage facilities are provided. Waste gas from the calcination furnaces contains dust with an aluminium oxide content which is deposited in dry filters and recirculated. Dust emissions in cleaned waste gas are under 50 mg/m³.

The process most commonly used for extracting pure aluminium is igneous electrolysis. Aluminium oxide at approximately 950°C is dissolved in a molten mixture of aluminium fluoride and cryolite and separated by direct current into pure aluminium and oxygen. The liquid aluminium is periodically drawn off and cast.

The following emissions and raw materials occur with the extraction of pure aluminium:

- primary alumina dust during storage, transport and charging;
- primary dust during anode production (petroleum coke etc.);
- volatile binding agents, fluorine from anode residues in the waste gas from the anode burning kilns;
- fluorides (dust and gaseous form) in the pot waste gas containing CO/CO₂; hydrogen fluoride gas is highly corrosive, harmful to health and the environment (also affects plant growth);
- used cathodes, containing fluoride;
- furnace breakage materials with fluoride components;
- wastewater.

The following individual protection measures are necessary:

Fine dust: Use of enclosed conveying systems (e.g. pneumatic conveyors).

Anode production: Extraction of dust and gaseous emissions, electrostatic waste gas cleaning, wet-chemical fluorine separation. Use of fabric filters permits clean gas dust concentrations of under 20 mg/m³ and fluorine contents of under 1 mg/m³.

Pots: Pot encapsulation with anode gas extraction and waste gas cleaning, wet chemical fluorine recycling or combined dedusting and dry absorption in the Al₂O₃ fluidized bed with direct recirculation. Wet chemical separation with water recirculation produces a sludge which, after drying, can only be partly returned to the process. Dry absorption and return of the filter dust to the process is preferable as this relieves the burden on the water circuit. Clean gas dust contents of under 30 mg/m³ and fluorine compounds of under 1 mg/m³ are obtained with encased, centrally controlled, large-capacity furnaces with computerised waste gas regulation and dry absorption with fabric filter.

Cell house: Shop air extraction and cleaning is compulsory with non-encased furnaces. Can be retrofitted.

Cathode and furnace Dumping only on specially protected, single-purpose breakage: dumps Cryolite, used as a fluxing agent for the electrolysis, can be obtained by processing (fluorine recycling).

Wastewater: The discharge of wastewater from aluminium oxide production and aluminium smelting must satisfy the requirements laid down under the generally recognised standards regarding chemical oxygen demand for aluminium and fluorides.

With respect to noise, a distinction is made between noise emissions affecting the neighbourhood and those affecting the workplace. Emission from main noise sources can be restricted by encapsulation and by means of silencers on air intakes and outlets. A noise reduction plan should be prepared during the planning phase.

2.2 Heavy metal ore smelting

The composition of the concentrates or raw materials is crucial for the applicable smelting process and thus also for the nature and quantity of the environmental pollutants arising. Sulphidic ore concentrates are thus mostly smelted by pyrometallurgical processes, whilst hydrometallurgical processes are employed for oxidic, sulphidic-oxidic and complex ores.

Combined processes are also used in which, for instance, material roasted by a pyrometallurgical process undergoes further treatment by hydrometallurgy. The charge material is ore enriched by beneficiation.

· Pyrometallurgical process stages

Roasting: Partial or total desulphurization (dead roasting) of the charge material;

Sinter roasting: Roasting of sulphur with admission of air (conversion of sulphides to metal oxides and SO₂ gas) with simultaneous agglomeration of the roasted material for use in shaft furnaces;

Rolling: Metal oxide enrichment by controlled volatilization (Zn);

Smelting: Separation of gangue (slags): production of high grade metal sulphides (Cu₂S) by partial combustion of the sulphur content and reduction of metal oxides (PbO, ZnO) under coke combustion with air admission;

Fuming: Conversion of metal sulphide to metal in a converter;

Pyrometallurgical Cleaning molten metal of oxygen, sulphur, impurities refining: and tramp metals by intermetallic precipitation, slagging and/or volatilization;

Slag cleaning: Thermal processing of slags to extract metal components.

Numerous emissions and residual materials occur with the above processes:

- Waste gases of various origins
- Primary dust from the charge material,
- Dusts from volatilized metals, including lead, zinc, arsenic, tin, cadmium, mercury, selenium, tellurium and their compounds (condensed after cooling),
- gaseous materials including SO₂, HCl, HF, CO, CO₂;
- Wastewater from coolant circuits and waste gas scrubbing;
- Final slags with residual metal contents, sulphates, sulphides; possibility of polychlorinated dibenzo-dioxins and -furans with chlorinating methods (e.g. copper roast leaching process);
- Furnace breakage materials, containing arsenic, lead, cadmium, mercury and cyanide.

For protective measures to be effective, it is essential that all emissions, including diffuse emissions of gas and dust, be efficiently intercepted at their points of origin. Diffuse emissions can be intercepted by hoods, covers or encapsulation, also by constructional measures such as encasement of conveyor belts or enclosed bays. Roasting furnaces should not be outdoor installations.

Dust: Waste gases are normally dedusted in dry filter systems (cyclones, electrostatic precipitators, fabric filters). Dedusting efficiency of up to 99.9% is possible, but depends on the permissible solid or pollutant content. Dusts can also be separated with fabric filters in lead smelting plants. Good separation efficiency is particularly important for the environment because waste gas from smelting contains toxic substances such as arsenic, antimony and lead in the form of fine dust. High-performance filtering separators have proved effective for fine dust separation.

Dust recycling for enriching and recovering metals. Separate pyrometallurgical or hydrometallurgical processing of tramp metals, for example As, Cd. Fabric filters are the principal method of dust separation. Clean gas dust contents of 10 mg/m³ can be obtained. Best values are around 1 mg/m³, e.g. in lead smelting plants.

SO₂ gas: Removed by waste gas scrubbing followed by neutralization. SO₂ concentrations in waste gas of over 3.5% are suitable for sulphuric acid production. In certain circumstances liquid SO₂, gypsum or elementary sulphur can be produced as a possible preliminary stage for industrial usage. Wet chemical waste gas cleaning processes are used for lower SO₂ concentrations. Only limited SO₂ concentrations and overall quantities may be discharged via chimneys.

Oil mists: If oil mists are present in the waste gases from shaft furnaces on account of the charge material, waste gases must undergo thermal afterburning.

Final slags/ Slags and furnace breakage material should be stored furnace breakage: in a specially protected single-purpose dump, since toxic and water-polluting substances such as heavy
metals may be released through leaching and weathering. Depending on residual metal content and
concentrations of other substances such as sulphides, sulphates, dioxins and furans, may possibly be used for road construction or reprocessing, or may have to be discarded.

Wastewater: Wastewater from waste gas scrubbing and slag granulation is polluted with heavy metals. Dissolved and undissolved metallic compounds in communal treatment plants lead to excessive metal concentrations in sewage sludges, restricting or preventing agricultural use.

Measures for reducing pollutant loads include minimizing wastewater volumetric flow by recirculation, recycling of treated wastewater and separating wastewater requiring treatment from that not requiring treatment. Extremely high standards must be applied to the discharge of wastewater with metal compounds toxic to humans and the ecosystem. State-of-the-art wastewater treatment systems include selective ion exchangers, microfiltration systems, reversal osmosis and thermal concentration processes. Production-specific concentrations of cadmium, mercury, lead, zinc, arsenic, copper, nickel and chromium should be limited.

Significant waste gas and emission reductions are achieved by combining several process steps in modern processes such as the flash cyclone reactor and the flash smelting method. Trials in a copper smelting plant and a lead smelting plant yielded reductions of 75%.

· Hydrometallurgical processes

Charge materials are oxidic ores, pretreated sulphidic ore concentrates which can be hydrometallurgically treated, or sulphidic concentrates which undergo oxidizing leaching. Hydrometallurgy processes also include extraction and refinement electrolysis.

Leaching: Treatment and lixiviation of the metals to be recovered, e.g. with dilute sulphuric acid for zinc production. For dump leaching in the case of very low-grade ores (bottom sealing necessary for soil and ground water protection);

Enrichment: Concentration of weak solutions by fluid extraction, using an organic solvent with simultaneous leachate cleaning.

Cleaning: Separation of accompanying substances and impurities by solids-fluid extraction and/or precipitation (hydroxide or sulphide precipitation, cementation);

Extraction: Electrolytic metal deposition with insoluble anodes (e.g. with Zn, Cu);

Refining: Electrolytic metal deposition with soluble anodes (e.g. with Cu, Pb).

The following environmentally relevant emissions and substances may be produced with the above processes:

Wastewater: Greater or lesser quantities of zootoxic and phytotoxic heavy metal components may be present in the wastewater, depending on the charge materials.

Leachate residues: Leachate residues contain metallic compounds harmful to the environment.

Waste gases: Sulphuric acid mists are produced in the extraction electrolysis; metal-containing vapours, e.g. in crude copper anode furnaces; organic solvents, e.g. xerosin, during liquid extraction in the enrichment process.

Anode sludge: This sludge contains metals and metal compounds, e.g. gold, silver, lead, tin, arsenic, antimony.

Spent electrolyte: The electrolyte contains dissolved metallic compounds of iron, nickel, zinc, arsenic and cobalt.

The following individual protection measures are necessary:

Wastewater: The wastewater volume must be reduced by appropriate measures, e.g. recirculation, recycling. Wastewater containing heavy metal pollutants must be treated by state-of-the-art methods. Wastewater contaminated with e.g. cadmium and mercury must be channelled and treated separately.

For wastewater treatment, especially low production-specific concentrations are to be stipulated, with residual concentrations of under 1 mg/l Cd and under 0.1 mg/l Hg to be achieved. Suitable processes include ion exchange, ultrafiltration and electrolysis.

Leachate residues: Residues must be converted by washing and neutralization processes to form compounds suitable for final dumping. Where technically possible, solvent residues are to be eliminated.

Waste gases: Permissible work-place concentrations for sulphuric acid mist can be achieved by appropriate room air ducting and, where necessary, waste air scrubbing.

By equipping a crude copper anode furnace with fabric filters, it was possible to separate gaseous metallic compounds to clean gas concentrations of 0.001 mg cadmium/m³, 0.05 mg lead/m³ and 1.9 mg/arsenic/m³. With liquid extraction using organic solvents, precautions must be taken against combustion and explosion and for fire fighting.

Anode sludge/ Special hydrometallurgical or pyrometallurgical electrolyte: measures are to be employed for the phased recovery of useful materials and the extraction of tramp metals; e.g. electrolytic deposition of arsenic and antimony or precipitation of nickel, iron or cobalt.

The extraction of zinc from zinc blende or galmei inevitably yields 3 to 4 kg cadmium per tonne of zinc as an alloy element in crude zinc or in the form of residues. Cadmium is extracted in primary zinc smelting plants by dry and wet absorption processes. The generally preferred wet processes and electrolytic cadmium extraction result in no direct production of cadmium dusts. The waste gases resulting from the smelting of cadmium to produce commercial formats can be introduced to the air for roasting, in order to achieve total waste gas cleaning.

Due to the toxic effects of cadmium, strict requirements must be imposed on work-place hygiene and waste air and water cleaning. In heavy metal ore smelting operations, main noise sources are wherever possible to be restricted by encapsulation and by means of silencers on air intakes and outlets. A noise reduction plan should be prepared at the project planning stage. In the case of operations generating high levels of noise, one should preferably begin by damping or eliminating occurrences and noise sources which arise only periodically.

To protect work-places from noise, installations should be extensively automated and equipped with appropriate control rooms. Protective equipment includes fireproof clothing, breathing equipment and ear protectors, depending on where they are working; protective helmets and safety footwear must be worn in all areas.

Measures for safety in the work-place and to protect the soil of the works site include all precautions to prevent the discharge of water-polluting substances. Special attention is to be paid to installations for producing, handling and using water-polluting substances. Relevant precautions include storage tanks with leakproof drip trays, overfilling safeguards, sealed and impermeable floor surfaces and leak testing, and these should be set forth in a manual.

2.3 Secondary smelting plants

Secondary smelting plants process mainly recycling material (shredder scrap, cables, batteries etc.), heavily contaminated mixed scrap, production scrap with alloy constituents that are difficult to remove, also slags, dross and other metalliferous residues. Predominantly pyrometallurgical processes are employed for metal recovery.

Environmental burdens stem mainly from impurities and pollutants present in the charge material, e.g. oil, paint, plastics, solvents or salts.

Special characteristics of the emissions and substances and requisite safeguards are as follows:

· Aluminium scrap melting plants

Salt slags: Aluminium scrap is usually melted down in rotary or hearth type furnaces under a layer of liquid salt to prevent ingress of air. The salt absorbs impurities present in the scrap and occurring during the melt-down process and produces salt slag (0.5 t/t Al).

Dumping these salt slags seriously pollutes the dump percolation water, therefore salt slag should be processed and returned to the melting process.

Waste gases: The molten aluminium is refined in converters using chlorine gas. The waste gases contain dusts, gaseous chlorine and fluorine compounds and chlorine gas; they may also contain organic substances which, depending on the operating conditions, may include traces of especially environmentally hazardous materials such as polychlorinated dibenzo-dioxins and -furans. Adequate separation of the dusts and inorganic compounds is achieved by dry absorption and fabric filters. Emissions of organic substances can be minimized by scrap sorting and cleaning or by special thermal afterburning of the waste gases.

· Copper scrap melting plants

Dust: When melting down copper-bearing residues, the interception and dry separation of emissions produced on charging and running-off are particularly important. Where oil mist occurs due to the impurity of the copper scrap, waste gases must undergo thermal afterburning before dust separation. For ecological and economic reasons, melting down should take place in a converter with top lances in a shop with waste air collection and cleaning rather than in shaft furnaces.

· Lead scrap melting plants

Waste gases: When recycling scrap batteries, PVC residues may give rise to gaseous inorganic chlorine compounds which are absorbed in the dust and in the slag.

Depending on the operating conditions, small quantities of polychlorinated dibenzo-dioxins and -furans may be present in the waste gases when recycling scrap cables. Emissions of health-endangering dioxins and furans can be restricted by careful sorting of scrap lead, scrap batteries and cables. Trials are in progress on activated-charcoal-based equipment for separation of these substances. Cleaning of scrap batteries results in varying quantities of battery acid (sulphuric acid) entering the washing water. The washing water is contaminated with lead, antimony, cadmium, arsenic and zinc. Separate interception and treatment is necessary.

2.4 Non-ferrous metal semifinishing works

In semifinishing works, the main problems of maintaining clean air stem from the upstream format foundries. These use large amounts of defined scrap in addition to primary metal which may call for pyrometallurgical smelting refining (e.g. with chlorine gas compounds in the case of Al).

Oily and plastic-coated scrap produces soot, oil mist, chlorine- and fluorine-bearing acid mist and similar substances on being melted down. Formation of polyhalogenated dibenzo-dioxins and -furans cannot be ruled out. For this reason scrap should be precleaned in fuming furnaces with afterburning chambers; depending on the permissible level of purity, waste gases are to be cleaned in electrostatic precipitators and/or gas scrubbers.

Waste gas from melting furnaces can contain metal oxides, volatile metalliferous vapours and halogen compounds which must be separated in dust filters or waste gas scrubbers. Through process automation and the use of additional reactors, even low-capacity secondary smelting plants (2,400 t/a) can achieve low clean gas emission values, e.g. 5 mg/m³ dust, less than 1 mg/m³ fluorine compounds, by chemisorption combined with cyclone and fabric filter. Separation efficiency for chlorine compounds can be as high as 98%.

Cooling bays for gas-emitting dross and slag are also to be connected to centralized waste air extraction systems.

Alkaline or acid solutions should be used for degreasing, cleaning and pickling metal surfaces. Organic solvents containing halogens should be avoided. Flushing water and used pickling and washing liquids are to be treated in neutralization plants.

Sludge residues are either pyrometallurgically processed in a smelting plant or, if they contain no pollutants, dumped. Vapours from heated pickling and rinsing baths must be extracted, precipitated by gas scrubbers and neutralized. Polluted waste must be placed on protected dumps with collection of percolation water.

As non-ferrous metal semifinishing plants are frequently situated close to residential zones, consideration must be given to noise reduction measures and the necessary distance.

3. Notes on the analysis and evaluation of environmental impacts

Non-ferrous metal industrial operations using thermochemical or pyrometallurgical processes produce considerable quantities of waste gases laden with environmentally harmful substances. Air protection measures must therefore be a priority.

The following examples illustrate the possible pollutant content of the waste gases:

- aluminium smelting plant, toxic fluorine components in the anode gas raw gas approx. 10 kg F/t Al
- copper smelting plant, sulphur dioxide in the waste gas raw gas approx. 2.6 t SO₂/t Cu

The values indicate that even in regions with low levels of existing pollution, waste gases from metal smelting plants must on no account be discharged uncleaned. Wet and dry processes are available for cleaning, dry processes being preferred for ecological and economic reasons.

Continuous monitoring involving measurements to verify the effectiveness of the separation systems is necessary both after erection of the plant and during its operation. Detailed descriptions for carrying out emission and immission measurements are contained in the guidelines of the German Association of Engineers VDI. In Germany the obligatory emission and immission values are detailed in TA-Luft (Technical Instructions on Air Quality Control).

In plants using hydrometallurgical processes, to reduce environmentally harmful substances to a minimum, intermediate products and residues must undergo repeated chemical treatment, filtration, electrolytic precipitation or scrubbing with subsequent neutralization. Wastewater from gas scrubbing or pickling plants may only be returned to receiving bodies of water once it has been chemically neutralized and freed of solids. Guideline values for permitted pollutant concentrations must be established for discharging wastewater in accordance with the state of art. Reference values may be obtained from the regulations in force in Germany. In every case care must be taken to ensure that drinking water and other water resources are not impaired. Analytical processes have been defined under German DIN standards to determine pollutant concentrations in wastewater; in Germany these are detailed in Allgemeine Verwaltungsvorschriften [General Administrative Regulations]. Routine measurements are also to be carried out to monitor the efficiency of water treatment and clarification plants. The scope of measurements and the inspection and maintenance intervals of wastewater - and waste gas - cleaning systems must be defined in an operating manual.

Contaminated material is to be stored in such a way as to prevent soil and groundwater contamination. Where possible, single-purpose dumps should be established, with sealing and percolation water collection and treatment systems which satisfy stringent requirements.

As in Germany, works environmental protection officers should be deployed in non-ferrous metal works who are totally independent of the production side. They are obliged to monitor adherence to the regulations.

In addition to monitoring external pollutant discharge, internal work-places must also be inspected for pollutant concentrations, noise and safety. Suitably qualified safety officers and a works doctor should be appointed for these purposes.

4. Interaction with other sectors

Normal annual production capacities of newer non-ferrous metal smelting plants are between 50,000 and 100,000 t. Allowance must be made for future capacity expansions. Due to the quantity of land occupied and the environmental pollution involved, projects cannot be considered in isolation. As early as the initial location selection phase, existing prior pollution of air, water and soil must be taken into account, making adequate allowance for the additional burdens imposed by such an industrial complex. As early as the planning phase, and when defining permissible immissions, effects on the environment must be considered from the point of view of community development. Adequate distancing from the nearest residential zones is to be guaranteed. Further details are contained in the environmental brief Planning of Locations for Trade and Industry.

Raw materials for smelting plants have to be extracted in large quantities from underground or surface mines. The environmental briefs on mining provide information on the environmental impacts. Efficient transport routes are necessary for transporting charge materials and products. Details are contained in the briefs Road Traffic, Railways and Railway Operation and Shipping.

A special secondary effect of the use of electrolytic processes is that their profitability, and particularly that of an aluminium smelting plant depends on the availability of cheap electricity. Additional pollution results from the erection or extension of power stations and the associated construction, particularly of hydraulic engineering works (see environmental briefs Thermal Power Stations and Power Transmission and Distribution).

A single-purpose dump must be established for non-recyclable products and waste, including slag and furnace breakage material (see environmental brief on Disposal of Hazardous Waste and Volume III, Compendium of Environmental Standards).

5. Summary assessment of environmental relevance

Processes and raw materials utilized in non-ferrous metal smelting plants for extracting aluminium, copper, lead and zinc, and also refining and smelting plants for further processing, produce emissions and raw materials which can pollute the environment. Of special significance are heavy metals which endanger health and in some cases are carcinogenic. In many countries this concerns especially the poorer sections of the population who are particularly at risk due to malnutrition and illness. The same of course applies to metal smelting plants other than those mentioned here.

Environmental damage can be reduced by selecting locations with relatively insensitive landscapes where there is unlikely to be any great effect on the regional productiveness of the natural environment. It is also necessary to exclude regions that are already heavily burdened with high existing or background levels of fluorine compounds and heavy metals. In this regard it should be noted that anthropogenic heavy metals are often more readily plant-available than lithogenic or pedogenic heavy metals.

Pyrometallurgical processes cause mainly air pollution in the form of gases, mists and dusts which must be minimized in gas scrubbers or returned for further processing. Apart from the ecological benefit, this form of emission reduction has the economic benefit of recovering valuable metals or producing sulphuric acids. Similar conditions exist for secondary smelting plants but with the additional problem of polluted charge materials. Depending on the operating conditions, halogen-bearing pollutants combined with organic materials are a particular potential source of polyhalogenated dioxin and furan emissions (waste gas emission concentrations of the order of nanograms).

Emissions and residues from hydrometallurgical processes on the other hand can pollute wastewater and dumps. Recycling of water in the circulation system is very important. Though it is state-of-the-art practice to recirculate liquid process materials such as acids, alkalies or solvents by regeneration, thereby reducing residues, these must be subsequently processed and the waste products neutralized in more or less costly stages to recover valuable metals and/or extract pollutants. Checks must be made in every case to determine whether pollution of groundwater or surface water is possible due to the storage or emission of primary, intermediate or end products. Pollutant yield and hence the necessary outlay for pollutant reduction is significantly lower in the case of semifinishing works.

A survey should be conducted in every case to determine whether agricultural use of the land in the vicinity of the works will be impaired by large-area pollution with phytotoxic and zootoxic heavy metals, especially zinc, copper, chromium, nickel and lead, taking into account long-term deposition, accumulation and reactivity in the soil. The environmental risk resulting from heavy metals in the soil must be distinguished according to the form of bonding of their elements which in turn depends on their origin.

Heavy metals, especially cadmium, can be injurious to human health through accumulation in the soil and in plants, with increased absorption through the food chain, leading in particular to kidney damage. Preliminary calculations of the expected additional environmental burdens are necessary for assessing these indirect effects via the air - soil - food chain. As a precaution, it is advisable to restrict agriculture in the immediate vicinity. Conflicts can be avoided or diminished by consulting the affected population groups at an early stage, possibly developing and planning new sources of employment. The question as to whether the increased environmental pollution poses additional health risks and hazards, e.g. for women and children (during pregnancy etc.) should be investigated, and adequate medical care provided. In addition to the pollution burdens, attention must also be paid to the noise emitted by the plant machinery. Depending on the plant design, noise levels as high as 125 dB(A) may be emitted. Noise levels can be minimized by noise reduction measures which are to be specified in a noise reduction plan. The wearing of personal ear protection must be obligatory in workplaces with noise levels in excess of 85 dB(A) and must be monitored.

For environmental protection measures to be effective, it is vital that personnel should be made sensitive to the issues and receive appropriate training. Although the smelting industry already has a range of proven methods and processes at its disposal for effective pollution control, their application can be excessively cost-intensive where pollutant emissions are too low for improvements to be economic but too high to be ecologically harmless. In these cases, bearing in mind the long-term effects of heavy metal pollution, one must give considerable weight to the needs of environmental protection, even putting this before the profitability of the individual plant.

The emphasis of current development work is towards totally enclosed circuits in the production system. The aim is to enclose the circuit to prevent harmful effects on the biosphere through ever better utilization of charge material, production of pure intermediate and end products without recourse to dumping, with improved emission protection and recycling of separated dusts and solids.

6. References

Statutory provisions, regulations

Abwassertechnische Vereinigung (ATV): Arbeitsblatt R 115, Hinweise für das Einleiten von Abwasser in eine öffentliche Abwasseranlage, January 1983.

Allgemeine Verwaltungsvorschrift zur Änderung der allgemeinen Rahmenverwaltungsvorschrift über Mindestanforderungen an das Einleiten von Abwasser in Gewässer. GMBl (joint ministerial circular). No. 37, 1989, p. 798.

Erste Allgemeine Verwaltungsvorschrift zum Bundes-Immissionsschutzgesetz (Technische Anleitung zur Reinhaltung der Luft - TA-Luft) dated 27.02.1986, GMBl (joint ministerial circular). 1986, Ausgabe A, p. 95.

Zweite Allgemeine Verwaltungsvorschrift zum Abfallgesetz (TA-Abfall) Teil 1: Technische Anleitung zur Lagerung, chemisch-physikalischen, biologischen Behandlung, Verbrennung und Ablagerung von besonders überwachungsbedürftigen Abfällen, vom März 1991, GMBl (joint ministerial circular). No. 8, p. 139.

39. Allgemeine Verwaltungsvorschrift über Mindestanforderungen an das Einleiten von Abwässer in Gewässer (Nichteisenmetallherstellung). GMBl (joint ministerial circular). No. 22, 1984, p. 350 - 351.

Deutsche Forschungsgemeinschaft: Liste maximaler Arbeitsplatzkonzentrationen (MAK-Wert-Liste), 1990, Mitteilung XXVI, Bundesarbeitsblatt 12, 1990, p. 35.

Environmental Protection Agency (EPA): Effluent Guidelines and Standards for Non-Ferrous-Metals, 40 CfR 421.

GVBl. des Landes Hessen, Teil 1, 31.03.1982.

Ministerium für Arbeit, Gesundheit und Soziales des Landes Nordrhein-Westfalen: Umweltprobleme durch Schwermetalle im Raum Stollberg, 1975, Düsseldorf.

5. Novelle zum Wasserhaushaltsgesetz: Mindestanforderungen nach § 7a, BGBl. I (Federal Law Gazette I), p. 1529.

Technische Anleitung zum Schutz gegen Lärm (TA-Lärm) vom 16.07.1968, Beilage BAnz. (Supplement to the Federal Law Gazette) No. 137.

Unfallverhütungsvorschriften: Hauptverband der gewerblichen Berufsgenossen-schaften, Bonn u.a. UVV-Lärm, VBG 121 of 01.01.1990.

VDI-Richtlinie 2262: Staubbekämpfung am Arbeitsplatz, December 1973.

VDI-Richtlinie 2285: Auswurfbegrenzung, Bleihütten, December 1975.

VDI-Richtlinie 2058, Blatt 3: Beurteilung von Lärm am Arbeitsplatz unter Berücksichtigung unterschiedlicher Tätigkeiten, April 1981.

VDI-Richtlinie 2560: Persönlicher Schallschutz, December 1983.

VDI-Richtlinie 2058, Blatt 1: Beurteilung von Arbeitslärm in der Nachbarschaft, September 1985.

VDI-Richtlinie 2102: Emissionsminderung, Kupferschrotthütten und Kupferraffinierien, Entwurf February 1985.

VDI-Richtlinie 2286: Emissionsminderung, Aluminiumschmelzflußelektrolyse, Entwurf January 1987.

VDI-Richtlinie 3929: Erfassen luftfremder Stoffe, Entwurf March 1990.

VDI-Richtlinie 2310: Blätter 30 und 31: Maximale Immissionswerte für Blei (Blatt 30) und Zink (Blatt 31) zum Schutze der landwirtschaftlichen Nutztiere, July 1991.

VDI-Richtlinie 3792, Blatt 3: Messen der Immissions-Wirkdosis von Blei in Pflanzen, April 1991.

Verordnung über Arbeitsstätten (Arbeitsstättenverordnung - ArbStättV) of 20.03.75, BGBl. I (Federal Law Gazette I), p. 729, 15 Schutz gegen Lärm.

Verordnung über gefährliche Stoffe, Gefahrstoffverordnung (GefStoffV) of 26. August 1986, BGBl. I (Federal Law Gazette I), p. 1470, in the version dated 23. August 1990, BGBl. I, p. 790.

Verordnung zur Bestimmung von Abfällen nach § 2 Abs. 2 des Abfallgesetzes of April 3 1990, BGBl. I (Federal Law Gazette I), p. 614.

Verordnung zur Bestimmung von Reststoffen nach § 2 Abs. 3 des Abfallgesetzes of April 3, 1990, BGBl. I (Federal Law Gazette I), p. 631.

Verordnung über das Einsammeln und Befördern sowie über die Überwachung von Abfällen und Reststoffen of April 3, 1990, BGBl. I (Federal Law Gazette I), p. 648.

Verordnung über Anlagen zum Lagern, Abfüllen und Umschlagen wassergefährdender Stoffe und die Zulassung von Fachbetrieben.

Scientific/technical papers

Bureau of Mines, Washington 1973, Control of Sulfur Oxide Emissions in Copper, Lead and Zinc Smelting.

Bußmann, H.: Stand und Entwicklung des Kupferrecyclings in: Fleischer, G., Abfallvermeidung in der Metallindustrie, p. 159 - 166, Ef Verlag für Energie und Umwelttechnik, Berlin 1989.

Corwin, T.K. et al: International Technology for the Nonferrous Smelting Industry, Noyes Data Corporation, Park Ridge NJ, 1982.

Dengler, H.: Behandlung schwermetallhaltiger Abwässer in: UTZ Materialien, 1989; Zentrum für Umwelttechnik beim Battelle-Institut Frankfurt am Main.

Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ), Dornier-Studie: Erstellung eines Kataloges von Emissions- und Immissionsstandards, October 1984.

Gesellschaft Deutscher Metallhütten- und Bergleute, Hauptversammlungsvorträge, Stuttgart 1972, Umweltschutz in der Metallhüttenindustrie.

Grün, M., Machelet, B., Podlesak, W.: Kontrolle der Schwermetallbelastung landwirtschaftlich genutzer Böden in der DDR.

Hartinger, L.: Taschenbuch der Abwasserbehandlung für die metallverarbeitende Industrie, Carl Hauser Verlag, Munich 1976.

Kirchner, G.: Die Bedeutung von Sekundäraluminium für die Aluminium-Versorgung in: Fleischer, G., Abfallvermeidung in der Metallindustrie, p. 173-179, Ef Verlag für Energie und Umwelttechnik, Berlin 1989.

Kloke, A.: Orientierungsdaten für tolerierbare Gesamtgehalte einiger Elemente in Kulturböden, Mitt. VDULFA 1980, p. 1 - 3 and 9 - 11.

Koch, C.T., Seeberger, J.: Ökologische Müllverwertung, Verlag C.F. Müller, Karlsruhe, 1984.

Landtag Nordrhein-Westfalen: Plenarprotokoll 11/28 of 03.05.1991.

Lärmquellen der Eisen- und Metallindustrie: Berufsgenossenschaftliches Institut für Lärmbekämpfung, Mainz 1973.

Merz, E.: Minimierung der Belastung durch Metalle und Metalloide, Vortrag im VDI-Kolloquium "Krebserzeugende Stoffe in der Umwelt", 23.04.1991. Mannheim, VDI-Bericht in Vorbereitung.

Miehlich, G., Lux, W.: Eintrag und Verfügbarkeit luftbürtiger Schwermetalle und Metalloide in Böden, VDI-Berichte No. 837, 1990, p. 27 - 51.

Persönliche Mitteilungen: Wirtschaftsvereinigung Metall e.V., Düsseldorf, 1991.

Rademacher, K.D., Koß, K.D.: Wassergefährdende Stoffe, Springer Verlag, Berlin 1986.

Riss, A. et. al: Schwermetalle in Böden and Grünlandaufwuchs in der Umgebung einer Kupferhütte in Brixlegg/Tirol, VDI-Berichte 837, 1990, p. 209-223.

Röpenack, von A.: Integrierter Umweltschutz - die Aufgabe der Zukunft, Erzmetall, 44 (1991), No. 2, p. 67 - 74.

Spona, K., Radtke, U.: Blei-, Cadmium- und Zinkbelastung von Böden im Emissionsgebiet einer Zinkhütte in Duisburg, VDI-Berichte 837, 1990, p. 165 - 183.

Ullmanns Enzyklopädie der technischen Chemie, 4. Auflage, Band 6 (Umweltschutz), Band 7 (Aluminium), Band 8 (Blei), Band 15 (Kupfer), Band 24 (Zink) - 1974/1983.

Umweltbundesamt [German Federal Environmental Agency] Berlin, April 1978: Stand der Technik bei Primär-Aluminiumhütten.

Umweltbundesamt [German Federal Environmental Agency] Berlin, March 1980: Richtlinien für Emissionsminderung in NE-Metallindustrien, incl. ausführliche Bibliographie.

Umweltbundesamt [German Federal Environmental Agency], Berlin, March 1983, R. Fischer: Maßnahmen und Einrichtungen zur Reinhaltung der Luft bei NE-Metallhütten und Umschmelzwerken.

Umweltbundesamt [German Federal Environmental Agency] Berlin, 1986: Altanlagenreport 1986, p. 59 - 73.

Umweltbundesamt [German Federal Environmental Agency] Berlin: Jahresberichte 1986, 1987, 1990.

Umweltbundesamt [German Federal Environmental Agency] Berlin, 1989: Luftreinhaltung '88, Tendenzen - Probleme - Lösungen, Erich Schmidt Verlag.

Umweltbundesamt Vienna: Montanwerk Brixlegg - Wirkungen auf die Umwelt, 1990.

VDI-Kommission Reinhaltung der Luft: Schwermetalle in der Umwelt, Düsseldorf, 1984.

VDI-Berichte 837, 1990, p. 593 - 612.

Verein Deutscher Ingenieure, Bericht 203, 1979, Schwermetalle als Luftverunreinigung - Blei, Zink, Cadmium.

Williams, Roy E.: Waste Production and Disposal in Mining, Milling and Metallurgical Industries,

Miller Freeman Publ., San Francisco, 1975.

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