This is a risk perception bulletin. Copper smelting and respiratory hazards

Mining and smelting copper from its natural ores is an expensive undertaking. Most of the world's known deposits contain only 1 to 2% copper: most of these ores are composed of sulfur, iron, arsenic, and other heavy metals. About 80% of new copper production uses copper sulfide ores, the pyrometallurgical and electrolytic processes and associated respiratory risks are summarized in this document. Highly effective respiratory protection may be indispensable during copper smelting, as part of a range of other control measures. In the following document, you will find general information on possible respiratory risks and the appropriate PPE to work safely in the different steps of copper production.

Mines/copper ores

Copper is mainly produced by reducing the metal content of mines mined and processed by smelting methods, since although elemental copper occurs very rarely in nature, it is extremely rare.

The majority of minerals extracted for their copper content are copper sulfide minerals, with the remaining minerals being copper oxide minerals. The mined material only contains 0.5 to 2% copper, most of the mined materials are unwanted sulfur compounds, arsenic compounds and other heavy metals (1) (2).

Copper can be found easily in a wide range of compounds, usually in the +1 oxidation state (also called cuprous) or in the +2 oxidation state (also called cupric).

Most copper (80%) is extracted and refined from copper sulphides by the processes of flotation, smelting and refining. With calcopyrite, bornite and calcosine sulphides being the most common and therefore the most widely used in copper production. The process of extraction, reduction and refining are complex and vary depending on the type of ore being processed. The following is a brief summary of the two main processes (1) (2) (3).

Methods of extraction

Minerals containing copper are mainly extracted from igneous rocks of open pit mining (quarries), but extraction by underground mining continues.

Copper sulfide: Pyrometallurgical process

Concentrate/grinding production

Copper sulfide mines undergo several steps of crushing and sanding to generate small-sized rock pieces. Then they are ground wet to obtain fine particles for quick formation of a sludge. Ground copper sulphide ore is mixed with water, surfactants and xanthates or other reagents to form a sludge in which the sulphide particles have become hydrophobic. By stirring or generating air bubbles with the flotation cells, copper sulfide mineral particles float to the surface in the form of foam, which is removed, sent for purification to remove unwanted minerals and silicon and then dried and sent for roasting and further smelting.

Foundry

Modern methods use direct or instant casting. The first step is to heat the mineral in furnaces to approximately 1200 °C with lime and silicon flux. Impurities of iron, sulfur, iron sulphide, iron oxide and other minerals are removed as they form a slag on the surface of the molten material or copper sulphide, also known as mata”.

2 CuFeS2 + 3 O2 → 2 FeO + 2 CuS + 2 SO2

Iron sulfide oxidizes to form iron oxide, releasing significant amounts of sulfur dioxide. The iron oxide then also reacts with the silicon to form a less dense slag that floats to the surface of the “matte”, which can be quickly removed.

2 FeS + 3 O2 → 2 FeO + 2 SO2

2 FeO + SiO2 → Fe2SiO4

Conversion

Copper sulphide is reduced to copper by oxidizing sulfur with air injection. Copper is known as black copper” because of the trapped bubbles of sulfur dioxide. Black copper has an approximate purity of 98-99%. There will be copper oxide present or it will be lost in the slag, with other metallic impurities.

CuS + O2 → Cu + SO2

2 CuS + 3 O2 → 2 CuO + 2 SO2

Refined by Fire

Any remaining copper oxide is reduced to copper by the injection of methane gas, increasing purity to 99%.

4 CuO + CH4 → 4 Cu + CO2 + 2H2O and the other two

Refined electrolyte

The molten copper is poured into molds to form copper anodes, for preparation for electrolytic refining. Copper anodes are immersed in an electrolyte of copper sulfate or sulfuric acid. The anode copper is gradually plated into thin sheets of pure copper or stainless steel that acts as the cathode. After 7-14 days, the cathodes are removed and the refined copper of approximately 99.9-99.99% purity is removed from the cathodes. Precious metal contaminants such as silver, gold, selenium and tellurium settle to the bottom of the electrolytic tank. Pollutants like arsenic and zinc remain in the electrolyte.

Leaching

Copper oxides are simply crushed to generate a large surface aggregate, which is carefully placed in a large outdoor leaching cap or leaching tanks. Sulphuric acid is applied to the top of the mine, dissolving the copper minerals in a copper sulfate solution. The loaded” leaching solution is collected and sent for extraction.

Extraction

In solvent extraction, copper is extracted from the leaching loaded solution by an organic solvent in an aqueous solution and the acidic solution is recovered.

Electricity generation

The copper solution undergoes electrolysis, depositing copper into the starting cathodes of very high purity copper foil. Other pollutants accumulate at the bottom of the electrolytic tank and can be recovered.

Image from (2)

What are the risks of copper production?

A wide range of aerial emissions can be generated during the production of copper, such as sulphur dioxide, arsenic, cadmium, copper, lead, mercury, particulate matter from smelting as well as particulate matter from other sources (3).

Sulphur dioxide

Sulphur dioxide is a dense colourless gas with a pungent odor and is produced in significant quantities from the smelting of sulphur ore for general elemental copper, zinc and other metals.

Sulphur dioxide (as sulphuric acid, pressurised/refrigerated liquid sulphur dioxide or even as sulphur) is recovered as a by-product in many processes (3). Sulphur dioxide is frequently used in various sectors, particularly the chemical, food and paper industries due to its bleaching, biocidal and preservative properties.

The main route of exposure for workers in the smelting and refining of copper, zinc and other metals is by inhalation of sulphur dioxide (S02). Other

Health effects

Health effects (6) (7) may include:

Serious health effects

• Eye and upper respiratory tract irritation
• Possible trigger for an asthma attack in some people
• Cough, wheezing, shortness of breath and even chest pain
• Pulmonary edema and death

Chronic health effects:

• Chronic obstructive pulmonary disease with long term low-level exposures

For more information on sulphur dioxide, see the 3M: sulphur dioxide

Arsenic

Arsenic can be found in elemental form but in general industry exposures to inorganic arsenic compounds such as arsenic trioxide, arsenic trichloride, arsenic trisulfide, sodium arsenate, arsenate salts and gallium arsenide (8).

Arsenic is used in many metal alloys but is also found in many copper and zinc mines. Workers in the non-ferrous base metals sector are at risk of exposure to arsenic and inorganic arsenic compounds (9). Workers in these sectors may be exposed to arsenic or arsenic compounds through inhalation of dust and fumes, ingestion, skin exposure or eye contact.

Health effects

Health effects may include (9) (10) (11) (12) (13) (14) (15):

Serious health effects

• Eye and upper respiratory tract irritation
• This is allergic dermatitis.
• Stomach problems such as gastroenteritis, nausea and vomiting, which in high doses can lead to severe fluid loss, hemorrhagic gastritis, loss of consciousness and death.

Chronic health effects:

• Skin conditions such as keratosis, discoloration, inflammation, lesions, acne and cancer
• Circulatory and cardiovascular problems, particularly sudden vascular contractions
• Damage to the nervous system
• Various forms of cancer such as, for example, the strong association with lung cancer in copper smelting, in addition to other cancers of the respiratory tract, skin, liver, kidneys and bladder

For more information on arsenic, see the 3MArsenic.

Cadmium

Cadmium is widely used with other metals, to form alloys or as a protective plate. Cadmium is also used with nickel to produce nickel-cadmium batteries. Because of its use in alloys and plating of other metals, metalworkers may be exposed to cadmium or cadmium dioxide (a brown smoke) when welding or sanding certain metals. Exposure to cadmium oxide smoke is also commonly associated with zinc smelters and to a lesser extent copper smelters.

Inhalation of dusts and fumes is the main method of occupational exposure to cadmium and cadmium compounds, cadmium oxide being a concern for acute exposures.

Health effects

Health effects may include (12) (16) (17) (18):

Serious health effects (cadmium oxide)

• Eye and upper respiratory tract irritation
• Flu-like symptoms such as cough, headache, dizziness, chills, fever, dyspnea and even chest pain.
• If ingested, gastrointestinal problems such as nausea, diarrhoea, vomiting, cramping and excessive salivation may occur.

Chronic health effects (all forms of cadmium):

• Respiratory damage such as chronic obstructive pulmonary disease (COPD)
• Renal injury
• Bone damage
• Alteration of fertility and foetal development (cadmium chloride)
• There is sufficient evidence that cadmium and cadmium compounds are carcinogenic in humans, associated with lung, kidney and prostate cancers (19), although associations with some compounds are weaker.

For further information on cadmium, see the Package Leaflet of 3M: cadmium

Copper

Copper has many uses due to its thermal and electrical conductivity, in metal alloys, in addition to its malleability and corrosion resistance.

In all applications and sectors, workers may be exposed to copper through inhalation of dust and smoke, ingestion and skin exposure to liquid chemicals. Workers may also be exposed to dust and smoke during copper smelting and refining.

Health effects

Health effects are commonly associated with severe short-term adverse health effects, mainly “metal smoke fever” from the smelting of copper-containing alloys (20).

Serious health effects:

• Eye and upper respiratory tract irritation
• Flu-like symptoms such as cough, headache, dizziness, chills, fever, dyspnea and even chest pain.

Chronic health effects:

• Gastrointestinal problems such as nausea, diarrhoea and vomiting have been reported to be associated with long-term excessive exposure to drinking water.

For more information on copper, see the 3MThe copper.

Lead

Lead and lead ores are commonly found in copper ores and can cause workers exposure during smelting and refining processes. The main methods of exposure are inhalation of particles, fumes and vapours and ingestion of particles due to poor hygiene practices (e.g. lead contamination from hands, food, drink and through tobacco).

Health effects

Lead can easily enter the bloodstream from the lungs and then accumulate in the body's bones over time. Short-term health effects are unlikely, but long-term exposures can cause lead levels to rise too high and the health effects become apparent.

Health effects may include (12) (21) (22) (23):

Serious health effects:

• Flu-like symptoms (chills, fever, muscle pain) and may cause respiratory damage

Chronic health effects:

• Anaemia and other red blood cell disorders
• Liver, kidney and lung diseases
• Gastrointestinal problems
• Sterility
• Encephalopathy (altered mental state)
• Damage to the nervous system
• Neurological developmental problems, particularly in the early stages of fetal development.

For further information on lead, see the Package Leaflet of 3MLead.

Mercury

Although most commonly associated with gold smelting where mercury is used in the extraction process, mercury can be found in some copper mines and emissions and exposures can occur in copper smelting and conversion processes (24).

The main method of exposure is the inhalation of elemental mercury vapours, it is important to note that significant levels of mercury may occur at high temperatures. Inhalation of powders such as mercury salts is also possible.

Health effects

Health effects may include (12) (25) (26):

Serious health effects:

• Irritation of the upper respiratory tract
• Fever

Chronic health effects:

• Damage to the nervous system: psychomotor effects
• Gastrointestinal problems
• Anemia
• Renal disorders

For more information on mercury, please refer to the 3MIt is mercury.

Particles

Considerable quantities of particulate matter (dust and fumes) can be generated at most stages of the production process. From mineral extraction, crushing, sanding, grinding and handling, to fume from molten materials, to sludge cleaning emissions from electrolytic processes in addition to general maintenance procedures (cleaning of chimneys and filters, refractory maintenance, etc.).

General epidemiological associations have been observed between exposure to particulate matter (atmospheric particles with diameters less than 2,5 μm) and PM10 (particles with diameters less than 10 μm) and a wide range of health effects such as mortality and chronic lung and cardiovascular disease (27).

References

1. Manufacturing Process of Copper. The Balance. [En línea] [consultado el 21 de septiembre de 2018]. . https://www.thebalance. i'm not going to tell you.

2. the European Copper Institute. Processes: copper mining and production. The Copper Alliance. [En línea] [consultado el 21 de septiembre de 2018]. . https://www.copper.org/education/copper-production/.

3. the World Bank Group. Pollution and Prevention and Abatement Handbook 1998. It's 1999.

Pulmonary Impairment from Chronic Exposure to Sulfur Dioxide in a Smelter. It is not possible to determine the concentration of the active substance. It is not recommended to use any of the following:.

Arsenic exposure and mortality: a case-referent study from a Swedish copper smelter. It's not a problem. In addition to the above, the Commission considers that the information provided by the Member States is not sufficient to justify the imposition of measures. 8 to 15.

Sulphur dioxide (SO2) - Air quality fact sheet. Australian Government - Department of Environment and Energy. [En línea] [consultado el 24 de septiembre de 2018]. . http://www.environment.gov.au/protection/ the commission shall, by means of implementing acts, adopt implementing acts laying down detailed rules for the application of this regulation.

7. Agency for Toxic Substances and Disease Registry (ASTDR). Toxic Substances Portal - Sulphur dioxide. [En línea] [consultado el 26 de septiembre de 2018]. . https://www.atsdr.cdc.gov/substances/ toxsubstance.asp? toxicity is 46.

8. Health and Safety Executive (HSE). INDG441 - Arsenic and you. Working with arsenic - are you at risk?

9. —. RR595 - The burden of oocupational cancer in Great Britain - Technical Annex 6: Lung cancer The burden of oocupational cancer in Great Britain - Technical Annex 6: The burden of oocupational cancer in Great Britain - The burden of oocupational cancer in Great Britain - The burden of oocupational cancer in Great Britain - The burden of oocupational cancer in Great Britain - The burden of oocupational cancer in Great Britain - The burden of oocupational cancer in Great Britain - The burden of oocupational cancer in Great Britain - The burden of oocupational cancer in Great Britain - The burden of oocupational cancer in Great Britain - The burden of oocupational cancer in Great Britain - The burden of oocupational cancer in Great Britain - Technical Annex 6: Lung cancer. [En línea] 2007 http://www.hse.gov.uk/research/rrpdf/rr595ann6.pdf.

10. the International Agency for Research on Cancer (IARC). Monograph - Arsenic and Arsenic Compounds. This is 2018.

11. Occupational health and safety administration (OSHA). Health and Safety Topics - Arsenic. [En línea] [consultado el 24 de septiembre de 2018]. . https://www.osha.gov/SLTC/arsenic/index.html.

12. Smedley, J, Dick, F and Sadhra, S. Oxford Handbook of Occupational Health (second edition). 2013.

13. National Occupational Health and Safety Commission (Worksafe Australia). Aresenic and its compounds. 1989.

14. Health and Safety Executive (HSE). RR858 - The burden of occupational cancer in Great Britain - Lung Cancer. 2012.

15. Agency for Toxic Substances and Disease Registry (ASTDR). Toxic Substances Portal - Arsenic. [En línea] [consultado el 26 de septiembre de 2018]. . https://www.atsdr.cdc.gov/substances/toxsubstance.asp?toxid=3.

16. Health and Safety Executive (HSE). INDG391 - Cadmium and you. Working with cadmium: Are you at risk?

17. Occupational Safety and Health Administration (OSHA). Safety and Health Topics - Cadmium. [En línea] [consultado el 24 de septiembre de 2018]. . https://www.osha.gov/SLTC/cadmium/healtheffects.html.

18. Agency for Toxic Substances and Disease Registry (ASTDR). Toxic Substances Portal - Cadmium. [En línea] [consultado el 26 de septiembre de 2018]. . https://www.atsdr.cdc.gov/substances/toxsubstance.asp?toxid=15.

19. International Agency for Research on Cancer (IARC). IARC Monograph - Cadmium and Cadmium Compounds. 2018.

20. Agency for Toxic Substances and Disease Registry (ASTDR). Toxic Substances Portal - Copper. [En línea] [consultado el 26 de septiembre de 2018]. . https://www.atsdr.cdc.gov/phs/phs.asp?id=204&tid=37.

21. Occupational Safety and Health Administration (OSHA). Safety and Health Topics - Lead. [En línea] [consultado el 24 de septiembre de 2018]. . https://www.osha.gov/SLTC/lead/.

22. Health and Safety Executive (HSE). Lead and you. Working safely with lead.

23. Occupational Safety and Health Administration (OSHA). Safety and Health Topics - Lead.

24. International Labor Office (ILO). Smelting and Refining Operations. Encyclopaedia of Occupational Health & Safety. [En línea] [consultado el 1 de octubre de 2018]. . http://www.iloencyclopaedia.org/part-xiii-12343/metal-processing-and-metal-working-industry/ content/smelting-and-refining-operations.

25. Occupational Safety and Health Administration (OSHA). Safety and Health Topics - Mercury. [En línea] [consultado el 24 de septiembre de 2018]. . https://www.osha.gov/SLTC/mercury/index.html.

26. Health and Safety Executive (HSE). CRR76 - Mercury and its Inorganic Divalent Compounds. nineteen ninety five.

27. World Health Organization (WHO). Health effects of particulate matter. 2013.

28Risk perception bulletin. copper smelting