Copper Acetates

Basic copper acetate (verdigris) was at one time made in France by interleaving copper metal sheets with fermented grape skins and dregs left after wine manufacture. After some time when the copper sheets had become coated with verdigris they were removed, exposed to the air for a few days and then replaced. This process was repeated until the whole sheet had become corroded. The resulting product was known as blue verdigris and was used as a fungicide at 1 kg basic copper acetate in 500 litres water.

Present manufacture is based on the action of acetic acid on copper metal, copper oxide or copper carbonate. They can also be prepared by treating a copper sulphate solution with lead acetate. Copper acetates are used as an intermediate in the manufacture of Paris green (cupric aceto-arsenite); as a catalyst in a number of organic reactions including rubber aging; as a chemical in textile dyeing; and as a pigment for ceramics. Copper acetates have also been used for impregnating kraft paper to produce an anti-tarnish wrapping paper for high grade silver ware.

Cuprous Oxide

Can be produced either electrolytically from copper or by the action of alkaline reducing agents on copper sulphate solutions. Formulated proprietary brands of cuprous oxide are extensively employed as fungicides and seed dressings. Another important application is in anti-fouling paints. Other uses include the colouring of porcelain and glass.

Cupric Oxide (black copper oxide)

Can be produced either by adding caustic soda to hot copper sulphate solutions or by treating copper scale with nitric acid and heating to redness. Cupric oxide is used in the ceramic industry for imparting blue, green or red tints in glasses, glazes and enamels. It is occasionally employed for incorporation in mineral supplements for insuring against an insufficiency of copper in the diet of animals. Among its other uses is the preparation of cuprammonium hydroxide solutions for the rayon industry.

Cupric Chloride

Obtained either by dissolving cupric oxide in hydrochloric acid or by the action of chlorine on copper. Its principal use is in the petroleum industry for sweetening (catalytic oxidation of the mercaptans) and as an ingredient of catalysts for other chemical processes. It is also used as a mordant in calico printing and dyeing.

Copper Oxychloride

Is a basic copper chloride and is usually manufactured either by the action of hydrochloric acid on copper metal or by the air oxidation of cuprous chloride suspensions. It has a number of applications, by far the most important being as an agricultural fungicide for which purpose it is extensively employed in formulated form as dusts, wettable powders and pastes.

Cuprous Chloride

Prepared either by heating a solution of cupric chloride with copper turnings or by the action of a reducing agent, such as sulphur dioxide, on a mixture of common salt and copper sulphate solution. The petroleum industry uses cuprous chloride in their "oil sweetening" process. Ammoniacal solutions of cuprous chloride are employed for the absorption of any carbon monoxide which may be present in a gas as an impurity.

Cupric Nitrate

Produced either by dissolving copper carbonate in nitric acid or direct from copper and nitric acid. It has a number of small uses, such as in ceramics, in dyeing as a mordant, in fireworks and in photography.

Copper Cyanide

Manufactured from sodium cyanide and copper sulphate. It is mainly used for copper electroplating.

Copper Soaps

Usually made by the interactlon of the corresponding soap with copper sulphate solution. Small quantities of these, such as copper stearate, copper oleate and copper abietate (from resins), are employed mainly for rot-proofing textiles, ropes, etc. They are also used in paints as they are soluble in oils, white spirits, etc.

Copper Naphthenate

Usually manufactured either from copper sulphate and naphthenic acid in combination with an alkali or by heating naphthenic acid and copper oxide. It is widely used as an oil-based wood preservative and as a rot-proofing agent.

Anhydrous and Monohydrated Copper Sulphate

Obtained by heating copper sulphate pentahydrate when four molecules water of crystallization are removed the product becomes copper sulphate monohydrate which is green in colour. At a higher temperature all the water of crystallization is removed and anhydrous copper sulphate is the white powder which results. They can also be obtained by crystallization from copper sulphate pentahydrate in boiling sulphuric acid. The main applications are in the production of proprietary wood preservatives and agricultural fungicides as well as for the production of a number of copper compounds. Sometimes they are utilised to detect the presence of moisture.

Copper sulphate has many agricultural uses (see Table A) but the following are the more important ones:

• Preparation of Bordeaux and Burgundy mixtures on the farm



• Control of fungus diseases



• Correction of copper deficiency in soils



• Correction of copper deficiency in animals



• Stimulation of growth for fattening pigs and broiler chickens



• A molluscicide for the destruction of slugs and snails, particularly the snail host of the liver fluke

Preparation of Bordeaux and Burgundy Mixtures on the Farm

Because of their importance to farmers, instructions concerning the dissolving of copper sulphate and the preparation of both Bordeaux and Burgundy mixtures have been included in the text.

Dissolving Copper Sulphate

Iron or galvanised vessels must not be used for the preparation of copper sulphate solutions. Plastic vessels, now freely available, are light and very convenient. To make a strong solution, hang a jute sack of copper sulphate so that the bottom of it dips a few inches only in the water. The copper sulphate will dissolve overnight. Copper sulphate dissolves in cold water to the extent of about 3 kg per 10 litres. If more than this is placed in the sack described above, then a saturated solution will be obtained and it may be used without serious error on the basis that it contains 3 kg copper sulphate per 10 litres.

Preparation of Bordeaux Mixture

Bordeaux mixture is prepared in various strengths from copper sulphate, hydrated lime (calcium hydroxide) and water. The conventional method of describing its composition is to give the weight of copper sulphate, the weight of hydrated lime and the volume of water in that order. The percentage of the weight of copper sulphate to the weight of water employed determines the concentration of the Bordeaux mixture. Thus a 1% Bordeaux mixture, which is the normal, would have the formula 1 :1:100the first 1 representing 1 kg copper sulphate, the second representing 1 kg hydrated lime, and the 100 representing 100 litres (100 kg) water. As copper sulphate contains 25% copper metal, the copper content of a 1% Bordeaux mixture would be 0-25 % copper. The quantity of lime used can be reduced considerably. Actually 1 kg copper sulphate requires only 0.225 kg of chemically pure hydrated lime to precipitate all the copper. Good proprietary brands of hydrated lime are now freely available but, as even these deteriorate on storage, it is safest not to exceed a ratio of 2:1. i.e. a 1:0.5:100 mixture.

In preparing Bordeaux mixture, the copper sulphate is dissolved in half the required amount of water in a wooden or plastic vessel. The hydrated lime is mixed with the balance of the water in another vessel. The two "solutions" are then poured together through a strainer into a third vessel or spray tank.

Preparation of a 1% Burgundy Mixture

Dissolve separately 1 kg copper sulphate in 50 litres water and 125 kg washing soda (or 0.475 kg soda ash) in 50 litres water and slowly add the soda solution to the copper sulphate solution with stirring. Control of fungus diseases

Bordeaux and Burgundy mixtures have been found effective in controlling a whole host of fungus diseases of plants. Normally a 0.5 % to 1 % Bordeaux or Burgundy mixture applied at 2 to 3 week intervals suffices to control most copper-susceptible fungi.

Generally once the fungus spores have alighted on the host plant and penetrated the tissues it is difficult to control them. The principle of control must in most cases depend on protection, ie preventing the fungus spores from entering the host tissues. Copper fungicides are noted for their tenacity and for this reason are much to be preferred in areas of high rainfall.

The simplest method of control is to apply a protective coating of Bordeaux or Burgundy mixture (or other copper fungicide) to the susceptible parts of the plant, so that spores alighting on them come in contact with the protective film of copper and are killed instantly. It is thus important to remember that the first spraying must ideally be made just before the disease is expected and continued at intervals throughout the susceptible period. For this reason it is important to take advantage of the early warning schemes which are in operation to ensure greater accuracy of the timing of the first spraying.

It must also be remembered that fungi are plants and that control measures that will kill them may not always leave the host plant unaffected. The use of too concentrated a fungicide mixture must therefore be guarded against, particularly for the early sprays.

Copper fungicides have been reported effective against numerous plant diseases. A list, by no means exhaustive, of some 300 diseases that have been found amenable to control by copper fungicides, appears in Table B.

Correction of Copper Deficiency in Soils

Where copper deficiency has been confirmed by soil analysis or field diagnosis, whether in plants or animals, it can be corrected very simply either by applying 50 kg copper sulphate per hectare in the form of a fertiliser before sowing or by spraying the foliage of the young cereal plants, when they are about 150 mm high, with 750 grams copper sulphate (dissolved in from 400 to 2,000 litres water) per hectare. The soil application has generally given the better results and has the advantage that it may have a residual effect for more than ten years. The foliar application has to be given annually to each crop. An alternative is to add a copper containing slag (normally about 1% to 2 % copper) at a rate of a tonne to the hectare.

Correction of Copper Deficiency in Animals

A method of correcting copper deficiency in livestock is to treat the soil on which animals graze. For example, in Australia and New Zealand swayback in lambs is being prevented by top dressing copper deficient pastures with 5 to 10 kg copper sulphate per hectare some time before lambing begins.

Other methods include drenching periodically with a copper sulphate solution; incorporating copper sulphate in salt and other animal licks; or by what is probably the most general method, incorporating copper sulphate along with other minerals and vitamins in the form of carefully blended supplements in the feeding stuffs.

Stimulation of Growth for Fattening Pigs and Broiler Chickens

The inclusion of up to as much as 0.1% copper sulphate in the diet of bacon and pork pigs and broiler chickens stimulates appetite and produces increased growth rate with a marked improvement in feed conversion.

A molluscicide for the destruction of slugs and snails, particularly the snail host of the liver fluke. All likely habitats of the liver fluke snail should be treated with copper sulphate at the rate of 25 kg to the hectare at least twice a year in June and August (northern hemisphere) or December and February (southern hemisphere).

Copper sulphate, blue stone, blue vitriol are all common names for pentahydrated cupric sulphate, Cu S04 5 H20, which is the best known and the most widely used of the copper salts. Indeed it is often the starting raw material for the production of many of the other copper salts. Today in the world there are more than 100 manufacturers and the world's consumption is around 200,000 tons per annum of which it is estimated that approximately three-quarters is used in agriculture, principally as a fungicide.

Manufacture In the production of copper sulphate virgin copper is seldom, if ever, used as the starting raw material. Copper ores are used in countries where these are mined. For the bulk of the world's production nonferrous scrap is the general source. The scrap is refined and the molten metal poured into water to produce roughly spherical porous pieces about the size of marbles which are termed "shot". This shot is dissolved in dilute sulphuric acid in the presence of air to produce a hot saturated liquor which, if the traditional large crystals of copper sulphate are required, is allowed to cool slowly in large cooling vats into which strips of lead are hung to provide a surface for the crystals to grow on. If the granulated (snow) crystal grades are desired, the cooling process is accelerated by agitating the liquor in water cooled vessels.

Other methods of production are:

• By heating copper scrap with sulphur to produce copper sulphide which is then oxidised to form copper sulphate.



• By heating copper sulphide ores to produce copper oxide which is then treated with sulphuric acid to form copper sulphate.



• By slow leaching in air of piles of low grade ore. Bacterial action is sometimes employed to hasten the process. A solution of copper sulphate drains away from such heaps.

Commercially copper sulphate contains 25 % metallic copper and is sold with a guaranteed minimum purity of 98 % copper sulphate. It is produced in a number of grades varying from large crystal lumps, of 25 mm or more in diameter from which it appropriately derives the name bluestone, to very fine powders of almost the fineness of talcum powder. The four commonest grades, based on crystal diameter sizes, are:

• Large crystals (from 10 mm to 40 mm)



• Small crystals (from 2 mm to 10 mm)



• Granulated or snow crystals (less than 2 mm)



• Windswept powder (less than 0.15 mm)

Uses of Copper Sulfates

Copper sulphate is a very versatile chemical with as extensive a range of uses in industry as it has in agriculture. Its principal employment is in agriculture, and this role is described in some detail in the next section.

Up to a generation or so ago about its only uses in industry were as a mordant for dyeing and for electroplating, but today it is being employed in many industrial processes. The synthetic fibre industry has found an application for it in the production of their raw material. The metal industry uses large quantities of copper sulphate as an electrolyte in copper refining, for copper coating steel wire prior to wire drawing and in various copper plating processes. The mining industry employs it as an activator in the concentration by froth flotation of lead, zinc, cobalt and gold ores. The printing trade takes it as an electrolyte in the production of electrotype and as an etching agent for process engraving. The paint industry uses it in anti-fouling paints and it plays a part in the colouring of glass. Indeed, today there is hardly an industry which does not have some small use for copper sulphate. In Table A some of the many uses of copper sulphate are listed.

Copper compounds have their most extensive employment in agriculture where the first recorded use was in 1761, when it was discovered that seed grains soaked in a weak solution of copper sulphate inhibited seed-borne fungi. By 1807 the steeping of cereal seeds in a copper sulphate solution for a limited time and then drying them with hydrated lime became the standard farming practice for controlling stinking smut or bunt of wheat, which by then was endemic wherever wheat was grown. Flour milled from bunted wheat had to be fed to animals or sold cheaply to ginger bread makers who had found a way of masking its bad taste and colour with ginger and treacle. Within a few decades, so general and effective had become the practice of treating seed grains with copper sulphate that the appearance of more than a few bunted ears in a field of wheat was looked upon as a sign of neglect on the part of the farmer. So well have copper compounds controlled bunt that today this seed-borne disease is no longer of any economic importance.

The greatest breakthrough for copper salts undoubtedly came in the 1880's when the French scientist Millardet, while looking for a cure for downy mildew disease of vines in the Bordeaux district of France, chanced to notice that those vines, bordering the highways and which had been daubed with a paste of copper sulphate and lime in water in order to make the grapes unattractive to passers-by, appeared freer of downy mildew. This chance observation led to experiments with mixtures of copper sulphate, lime and water and in 1885 Millardet announced to the world that he had found a cure for the dreaded mildew. This mixture became known as Bordeaux mixture and saw the commencement of protective crop spraying.

Within a year or two of the discovery of Bordeaux mixture, Burgundy mixture, which also takes its name from the district of France in which it was first used, appeared on the scene. Burgundy mixture is prepared from copper sulphate and sodium carbonate (soda crystals) and is analogous to Bordeaux mixture.

Trials with Bordeaux and Burgundy mixtures against various fungus diseases of plants soon established that many plant diseases could be prevented with small amounts of copper applied at the right time and in the correct manner. From then onwards copper fungicides have been indispensable and many thousands of tons are used annually all over the world to prevent plant diseases.

As a generalisation, soils would be considered copper deficient if they contain less than two parts per million available copper in the context of plant health. However, where the soil contains less than five parts per million available copper, symptoms of copper deficiency may be expected in animals. The increasing use of chemical fertilisers which contain little or no copper are denuding soils of readily available copper and creating a deficiency of the element in plants and through them in animals. Copper compounds are now being added to the ever increasing copper deficient soils either direct or in combination with commercial fertilisers. This is particularly the case where the fertilisers are rich in nitrogen and phosphorus. Animals grazing on copper deficient pastures or obtaining an inadequate amount of copper through their normal diet will benefit from mineral supplements containing copper.

Copper sulphate, because of its fungicidal and bacteriecidal properties, has been employed as a disinfectant on farms against storage rots and for the control and prevention of certain animal diseases, such as foot rot of sheep and cattle.

To trace the history of copper compounds it would be necessary to go back much further than the fourth millennium BC. Records found in the tombs of the early Egyptians suggest that, at least, this ancient civilisation employed copper sulphate as a mordant in their dyeing process. Today, more than 5,000 years later, copper sulphate is still employed by the world's dyeing industry in the after treatment of certain dyes to improve their fastness to light and washing.

Another equally early recorded use for copper compounds was for the making of ointments and other medical preparations. Later, the Greek civilisation of the pre-Christian era of Hypocrates (circa 400 BC) saw the prescribing of copper sulphate for pulmonary diseases and by the 18th century AD it had come into wide clinical use in the western world, being employed for the treatment of mental disorders and afflictions of the lungs.

It is noteworthy that copper sulphate has lost none of its effectiveness over the centuries, neither have any harmful side effects been reported. Copper sulphate is still, however, highly prized by some inhabitants of Africa and Asia for healing sores and skin diseases. In the West it is widely used in baby foods and in mineral and vitamin tonics and pills.

Copper has a wide spectrum of effectiveness against the many biological agents of timber and fabric decay. It renders them unpalatable to insects and protects them from fungus attack. Copper sulphate has been in use since 1838 for preserving timber and is today the base for many proprietary wood preservatives.

The discovery more than 80 years ago that many algae are highly susceptible to copper, led to the use of copper salts by water engineers to prevent the development of algae in potable water reservoirs. They are also employed to control green slime and similar algal scums in farm ponds, rice fields, irrigation and drainage canals, rivers, lakes and swimming pools.

Another well known use for copper compounds is as a molluscicide for the control of slugs and snails. Less than one part of copper per million parts of water can control disease-transmitting aquatic snails, which are responsible for schistosomiasis or bilharzia in humans in tropical countries and fascioliasis or liver fluke of animals in both tropical and temperate climates.

In addition to their many uses in agriculture and biology, copper salts have an astonishing variety of industrial uses, chiefly of a specialised nature, and there is hardly an industry which does not have some small use for them. The following pages briefly describe a few of the more important copper compounds and list some of their uses with particular reference to copper sulphate.

It is worth noting that copper is an indispensable constituent of all living tissues and is essential for the normal growth and well being of plants and animals. Where it is lacking it has to be supplied. The minute quantities of copper needed for human health are usually obtained through the normal intake of food and water.

Copper and its compounds are not toxic like some other metals, such as lead or mercury. There are no records of any occupational diseases attributable to copper among people who have worked for many years with the metal or its salts. Indeed it has sometimes been said that such people often appear healthier and generally suffer less from colds and other ailments. Copper bangles and other adornments are reputed to relieve and prevent rheumatic pains. Copper water storage vessels, copper kettles and copper cooking pans have been used for generations

Here you will find articles that discuss how copper interacts with the environment in a variety of common applications . . . from plumbing to heat efficiency. The information has been broken down into four main sections: Recycling, Human Health, Drinking Water and the Natural Environment.

Recycling Copper

Technical Report
The U.S. Copper-base Scrap Industry and Its By-products — 2004 (2.1 MB).

For nearly 5,000 years, copper was the only metal known to man. Today, it’s one of the most used and reused of our “modern” metals...

An easy to read discussion on copper recycling by the British Copper Development Association.

An in-depth collection of articles in Innovations, our on-line e-zine, on how copper is recycled in individual products such as roofs, radiators, etc.

Trends in US copper alloy scrap and effects of product shifts
Copper alloy scrap provides about half of the copper consumed in the United States each year.

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Copper and Human Health

Please visit our new, expanded Copper and Human Health Section for content in this area. Also, note that copper can inhibit the growth of microbes, thus providing a measure of protection against harmful germs and bacteria in many environments. See Antimicrobial Copper Alloy Surfaces.

The Biologic Importance of Copper
The International Copper Association (ICA) has conducted annual reviews on the biological importance of copper since 1984. The reviews conducted since 1989 are available in this article.

Copper Roof Stormwater Runoff - Corrosion and the Environment
A well defined watershed was utilized to determines copper concentration, speciation and aquatic toxicity in stormwater runoff. Read the paper presented at the 2002 NACE conference.

Alternately, a summary of the early findings from this study as published in the April 1999 issue of Innovations.

Copper and Aquatic Life
Innovations spoke with Dr. Karl D. Shearer, Research Fisheries Biologist with the National Marine Fisheries Service about how copper, in natural quantities, is essential to marine life.

Environmental Impact
Read these four case studies of the impact of copper and the copper industry on the environment, or one of these articles from Innovations on how companies in the copper industry have worked to mitigate the environmental impact of copper extraction:

Trapping Sulphur: Kennecott-Outokumpu's flash smelter sets a new industry standard

The Secret to Staying Young: Kennecott Copper's Bingham Canyon Mine

The Best of Both Worlds: Phelps Dodge's environmental practices

Copper and Global Warming
A summary of articles from Innovations on the copper industry's efforts to help save the world from global warming:

Copper Increases Efficiency of Solar Cells

Air Conditioning & Refrigeration - New Research Program Focuses on Improvements for the 21st Century.

Copper Motor Rotors - Application of High Temperature Mold Materials to Die Cast the Copper Motor Rotor.

Direct Source Heat Pumps - CDA Backs DX Geothermal Heat Pump R&D.

Electric Vehicles

How the Copper Industry Helps Solve Corrosion Problems
The Copper Development Association Incorporated (CDA) recently organized
a symposium for technical personnel, in companies which produce plumbing tube and fittings. Six experts on pitting of copper presented their views of the field. Together with the State of Connecticut it has developed data on copper in stormwater runoff from a copper roof at the University of Connecticut.

Nebraska Calls for Changes in the "Copper Rule"
An article in Innovations about municipalities in Nebraska are attempting to gain relief from the burdens of complying with the Environmental Protection Agency's "Lead and Copper Rule."

Q & A with Hastings Utilities on the "Copper Rule"
Innovations interviewed Marvin Schultes, Manager Hastings Utilities for Hastings' views on the problems with complying with the EPA's Lead and Copper Rule.

Lead-free solders for drinking water plumbing systems
Since the Safe Drinking Water Act Amendments of 1986 lead-base solders have been replaced by tin-antimony and tin-silver solders. Find out more.

The Safe Drinking Water Act FAQ
The 1996 SDWA amendments contain new provisions to address the lead content of plumbing fittings and fixtures. Read about how this may affect you and about details of the SDWA and the amendments.