Copper

MEPS 531 INDUSTRIAL PROCESSES

COPPER

INTRODUCTION/ HISTORY

Copper is a chemical element in the periodic table that has the symbol Cu ( Latin: cuprum) and atomic number 29. It is a ductile metal with excellent electrical conductivity, and finds extensive use as an electrical conductor, heat conductor, as a building material, and as a component of various alloys. Copper is an essential nutrient to all high plants and animals. In animals, including humans, it is found primarily in the bloodstream, as a co-factor in

Copper has played a significant part in the history of mankind, which has used the easily accessible uncompounded metal for nearly 10,000 years. Civilizations in places like Iraq, China, Egypt, Greece and the Sumerian cities all have early evidence of using copper. During the Roman Empire, copper was principally mined on Cyprus, hence the origin of the name of the metal as Cyprium, "metal of Cyprus", later shortened to Cuprum. A number of countries, such as Chile and

Nevertheless, the price of copper rose rapidly, increasing 500% from a 60-year low in 1999, largely due to increased demand. This metal has come into the limelight on account of high volatility in prices. According to New Scientist (May 26, 2007) the earth has an estimated 61 years supply of copper left. Copper is a reddish-colored metal, with a high electrical and thermal conductivity ( silver is the only pure metal to have a higher electrical conductivity at room temperature). In oxidation copper is mildly basic. Copper has its characteristic color because it reflects red and orange

Copper occupies the same family of the periodic table as silver and gold, since they each have one s-orbital electron on top of a filled electron shell. This similarity in electron structure makes them similar in many characteristics. All have very high thermal and electrical conductivity, and all are malleable metals. In its liquified state, a pure copper surface without ambient light appears somewhat greenish, another characteristic shared with gold. Silver

Due to its high surface tension, the liquid metal does not wet surfaces but instead forms spherical droplets when poured on a surface. Copper is insoluble in water (H2O) as well as in isopropanol. There are two stable isotopes, 63Cu and 65Cu, along with a couple dozen radioisotopes. The vast majority of radioisotopes have half lives on the order of minutes or less; the longest lived, 67Cu, has a half life of 61.8 hours. Numerous copper alloys exist, many with

Brass is an alloy of copper and zinc. Monel metal, also called cupronickel, is an alloy of copper and nickel. While the metal "bronze" usually refers to copper-tin alloys, it also is a generic term for any alloy of copper, such as aluminium bronze, silicon bronze, and manganese bronze. Copper is germicidal, via the oligodynamic effect. For example, brass doorknobs disinfect themselves of many bacteria within eight hours. This effect is useful in many applications. The purity of copper is expressed as 4N for 99.99% pure or 7N for 99.99999% pure.

Copper, as native copper, is one of the few metals to naturally occur as an uncompounded mineral. Copper was known to some of the oldest civilizations on record, and has a history of use that is at least 10,000 years old. A copper pendant was found in what is now northern Iraq that dates to 8700 BCE. By 5000 BCE, there are signs of copper smelting, the refining of copper from simple copper compounds such as malachite or azurite. Among archaeological sites in Anatolia, Çatal Höyük (~6000 BCE) features native copper artifacts and smelted lead beads,

Copper smelting appears to have been developed independently in several parts of the world. In addition to its development in Anatolia by 5000 BCE, it was developed in China before 2800 BCE, in the Andes around 2000 BCE, in Central America around 600 AD, and in West Africa around 900 AD. Copper is found extensively in the Indus Valley Civilization by the 3rd millennium BC. In Europe, Ötzi the Iceman, a well-preserved male dated to 3200 BC, was found with a

There are copper and bronze artifacts from Sumerian cities that date to 3000 BC, and Egyptian artifacts of copper and copper-tin alloys nearly as old. In one pyramid, a copper plumbing system was found that is 5000 years old. The Egyptians found that adding a small amount of tin made the metal easier to cast, so bronze alloys were found in Egypt almost as soon as copper was found. In the Americas production in the

The use of bronze became so pervasive in a certain era of civilization that it has been named the Bronze Age. The transitional period in certain regions between the preceding Neolithic period and the Bronze Age is termed the Chalcolithic ("copper-stone"), with some high-purity copper tools being used alongside stone tools. Brass was known to the Greeks, but only became a significant supplement to bronze during the Roman empire. In Greek the metal was known by the name chalkos.

In Roman times, it became known as aes Cyprium (aes being the generic Latin term for copper alloys such as bronze and other metals, and Cyprium because so much of it was mined in Cyprus). From this, the phrase was simplified to cuprum and then eventually Anglicized into the English copper. Copper was associated with the goddess Aphrodite/Venus in mythology and alchemy, owing to its lustrous beauty, its ancient use in producing mirrors, and its association

Mining for copper in the Philippines dates back to the 14th century when crudely smelted copper was traded by the Chinese. Significant production did not start until 1842 when the San Remegio Copper Mines, Inc. opened the Carawisan Mine in Antique. This was followed by Mankayan Mine in Benguet that was operated by the ContrabroFilipino Co. from 1864 to 1874. The American took little interest in the metal up until 1936 when the Mankayan Mine was reopened. Soon in 1939, the Hixbar Mine in Rapu-Rapu

The years after the war saw a rapidly emerging interest in copper and other base metals, almost at the expense of gold, which was plagued with depressed prices and mine rehabilitation problems. For its highgrade copper ore, the Lepanto Consolidated Mining Company reopened Mankayan Mine in 1948. New technologies were introduced for the economic extraction of large low-grade porphyry copper deposits. Thus, Atlas Mine in Cebu started production in

By the 1960s, a full-blown copper boom dominated the mining industry. The boom was accompanied by extensive exploration activities, which led to the discovery and opening of new porphyry copper mines such as Sto. Nino Mine in 1971 and Boneng-Lobo Mine in 1974. By 1974, 18 copper producing mines were in operation. The latter part of the 1970?s saw some of the newly opened copper mines struggling against high inflationary trends, high cost of money, and marginal ores. Ino-Capayang and the nearby Mogpog Mine of Consolidated Mines Inc.

Despite these indications of trouble, however, several new mines managed to start operation. Basay Mine in Negros, Dizon Mine in Zambales, Sabena and North Davao Mines in Davao del Norte, and Hercules Mine in Ilocos Norte opened between 1979 and 1981. During the early 1980?s the Philippines had 20 primary and secondary copper producers. However, due to the sluggish economic and political condition in the country, coupled with the outdated mining laws and regulations, most companies were forced to either scale down or shutdown its mining operations.

USES AND ECONOMICS

Copper is malleable and ductile, a good conductor of heat and, when very pure, a good conductor of electricity. It is used extensively, in products such as:  Piping, including, but not limited to, domestic water supply  Electronics:  Copper wire.  Electromagnets.  Printed circuit boards.  Electrical machines, especially electromagnetic motors, generators

 Electrical

relays, electrical busbars and electrical switches.  Vacuum tubes, cathode ray tubes, and the magnetrons in microwave ovens.  Wave guides for microwave radiation.  Integrated circuits, increasingly replacing aluminium because of its superior electrical conductivity.  As a material in the manufacture of computer heat sinks, as a result of its superior heat dissipation capacity to

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Structural Engineering:  Copper has been used as water-proof roofing material since ancient times, giving many old buildings their greenish roofs and domes.  Statuary: The Statue of Liberty, for example, contains 179,220 pounds (81.3 tonnes) of copper.  Alloyed with nickel, e.g. cupronickel and Monel, used as corrosive resistant materials in shipbuilding.  Watt's steam engine.

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Household Products:  Copper plumbing fittings and compression tubes.  Doorknobs and other fixtures in houses.  Roofing, guttering, and rainspouts on buildings.  In cookware, such as frying pans.  Most flatware (knives, forks, spoons) contains some copper (nickel silver).  Sterling silver, if it is to be used in dinnerware, must contain a few

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Coinage: As a component of coins, often as cupronickel alloy.  Coins in the following countries all contain copper: European Union (Euro), United States, United Kingdom (sterling) and Australia.  Ironically, U.S. Nickels are 75.0% copper by weight and only 25.0% nickel. 

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Biomedical applications: 

As a biostatic surface in hospitals, and to line parts of ships to protect against barnacles and mussels, originally used pure, but superseded by Muntz Metal. Bacteria will not grow on a copper surface

Copper(II) sulfate is used as a fungicide and as algae control in domestic lakes and ponds. It is used in gardening powders and sprays to kill mildew.  Copper-62-PTSM, a complex containing radioactive copper-62, is used as a Positron emission tomography radiotracer for heart blood flow measurements.  Copper-64 can be used as a 

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Chemical applications:  Compounds, such as Fehling's solution, have applications in chemistry.  As a component in ceramic glazes, and to color glass. Others:  Musical instruments, especially brass instruments and cymbals.  Class D Fire Extinguisher, used in powder form to extinguish lithium fires by covering the burning metal and performing similar to a heat sink.  Textile fibers to create antimicrobial

PRODUCTION STATISTICS

America is noted to have the richest mineable copper deposit in the world recorded at 7.68 million metric tons (MT), which is more than 62% of the total mine production for 1999. Leading producers like Chile and U.S.A at 4.38 million MT and 1.59 million MT, respectively were also noted in the same region. Combined mine production of Europe, Asia, Africa and Oceana accounts for about 48% for the same year which is minimal compared to that of Americas annual contribution. Mine production has been growing annually at an average growth

This was followed by 1998 at 6.9% growth, or 12.3 million MT. The highest mine production was recorded in 1999 at 12.36 million MT.

In terms of world production of refined copper by region, America ranks the highest at 4.0 million metric tons or 44.9% of the world total for 1999. Chile and U.S.A are the top producers from the same region, contributing 2.7 million metric tons and 2.1 million metrics tons, respectively. Likewise, top producers from Asia, such as Japan and China, posted as much as 1.3 million metric tons and 1.0 million metric tons, respectively. Production of refined copper grew at an annual average growth rate of 2.9% from 1990 to 1999. The highest growth periods were noted in 1996 at 7.8% and in 1997

Consumption of refined copper grew at an annual average growth rate of 2.8% from 1990 to 1999. The highest annual growth was noted in 1996 at 6.4% and lowest in 1991 at a negative annual growth of 0.9%. The major consumer of refined copper in 1999 was noted in Asia at 5.2 million metric tons, or 37.4% of the world consumption. This was followed by America at 4.2 million metric tons, or 30.5% and Europe at 30.1%, or at 4.1 million metric tons. The top four (4) countries comprising the leading consumers of refined copper in 1999 were U.S.A. at 3.0 million metric

World copper prices for the past ten (10) years from 1990 to 1999 were basically at a declining trend. This was reversed in 1995 when world price posted a 24.6% increase from 111.0 5c/lb in 1994 to 138.33 c/lb in 1995. The highest decline in world copper price was noted between 1997 and 1998, from 103.22 c/lb to 74.97 c/lb or a negative growth of 27.4%. This negative trend was due to the economic recession that hounded most economies throughout the nineties. The prolonged depressed state has played havoc to the supply and demand pattern. The gap in supply and demand occurred during the period since there was an

Copper reserve was estimated at 4.79 million metric tons in 1996. The biggest deposit was found in Cordillera Autonomous Region that is estimated at 1.83 million metric tons followed by Region 7 at 1.15 million metric tons.

Production of copper decreased from 698.17 dry metric tons (DMT) in 1990 to 151.22 dry metric tons (DMT) in 1999. The years 1992 and 1993 posted an increase in volume from 491.75 dry metric tons (DMT) to 526.22 dry metric tons (DMT), or at a rate of 8.0%, due to the increase in production of Marcopper Mining Corporation?s San Antonio Project and Maricalum Mining Corporation. As of 1999, there were three (3) remaining primary producers, namely: Philex Mining Corp., Maricalum Mining Corp. and Manila Mining Corp. Of the three (3) producers, Philex Mining Corp. ?

The price of Philippine copper (metal) had been fluctuating between a low of P44,793/DMT in 1993 to a high of P66,803/DMT in 1995. In terms of year-to-year growth, the highest was recorded between 1994 to1995 at an increase of 27.99%. Likewise, a negative growth of 14.27% was noted between 1995 to 1996.

RAW MATERIAL

Any mineral from which copper is extracted, including native copper, Cu; chalcocite, Cu2S; chalcopyrite, CuFeS2; bornite, Cu5FeS4; azurite, Cu3(CO3)2(OH)2; malachite, Cu2CO3(OH)2; and chrysocolla, CuSiO3.2H2O. Native copper and the copper sulphides are usually found in veins associated with igneous intrusions. Chrysocolla and the carbonates are products of the weathering of copperbearing rocks. Copper was one of the first metals to be worked, because it occurred in native form and needed little refining. Today the main producers are

 Copper

ores may refer to:

 Bornite  Chalcocite  Cuprite  Tennantite  Tetrahedrite  Malachite

Bornite is a sulfide mineral with chemical composition Cu5FeS4 that crystallizes in the orthorhombic system. It has a brown to copperred color on fresh surfaces that tarnishes to an iridescent purple. Its purple to bronze iridescence gives it the nickname peacock copper or peacock ore.

Bornite is an important copper ore mineral and occurs widely in porphyry copper deposits along with the more common chalcopyrite. Chalcopyrite and bornite are both typically replaced by chalcocite and covellite in the supergene enrichment zone of copper deposits. Bornite is also found as disseminations in mafic igneous rocks, in contact metamorphic skarn deposits, in pegmatites and in sedimentary cupriferous shales. It is important for its copper content of about 63 percent by mass and is found in Arizona, Butte, Montana, and Mexico. It has been reported since 1725, but in

Chalcocite, copper(I) sulfide (Cu2S), is an important copper ore mineral. It is opaque, being colored dark-gray to black with a metallic luster. It has a hardness of 2½ - 3. It is a sulfide with an orthorhombic crystal system.

Chalcocite is sometimes found as a primary vein mineral in hydrothermal veins. However, most chalcocite occurs in the supergene enriched environment below the oxidation zone of copper deposits as a result of the leaching of copper from the oxidized minerals. It is also often found in sedimentary rocks. It has been mined for centuries and is one of the most profitable copper ores. The reasons for this is its high copper content (67% atomic ratio and nearly 80% by weight) and the ease at which copper can be separated from sulfur. Still, it is not considered a primary source of copper ore due to its scarcity. Fine crystals of chalcocite are quite uncommon and are much

Since chalcocite is a secondary mineral that forms from the alteration of other minerals, it has been known to form pseudomorphs of many different minerals. A pseudomorph is a mineral that has replaced another mineral atom by atom, but it leaves the original mineral's crystal shape intact. Chalcocite has been known to form pseudomorphs of the minerals bornite, covellite, chalcopyrite, pyrite, enargite, millerite, galena and sphalerite. The term chalcocite comes from the

Cuprite is a mineral composed of copper(I) oxide Cu2O, and is a minor ore of copper.

Its dark crystals with red internal reflections are in the isometric system hexoctahedral class, appearing as cubic, octahedral, or dodecahedral forms, or in combinations. Penetration twins frequently occur. In spite of its nice color it is rarely used for jewelry because of its low Mohs hardness of 3.5 to 4. It has a relatively high specific gravity of 6.1, imperfect cleavage and a brittle to conchoidal fracture. The luster is sub-metallic to brilliant adamantine. The "chalcotrichite" variety typically shows greatly elongated capillary or needle like crystals forms. It is a secondary mineral which forms in the oxidized zone of copper sulfide deposits. It frequently occurs in association with native copper, azurite, chrysocolla, malachite,

Tennantite is a copper arsenic sulfosalt mineral. Its chemical formula is Cu12As4S13. It is found in hydrothermal veins and contact metamorphic deposits. It is grey-black, steel-gray, iron-gray or black in color. A closely related mineral, tetrahedrite (Cu12Sb4S13) has antimony substituting for arsenic and the two form a solid solution series. The two have very similar properties and is often difficult to distinguish between tennantite and tetrahedrite. Iron, zinc, and silver substitute up to about 15% for the copper site.

is a copper antimony sulfosalt mineral with formula: . It is the antimony endmember of the continuous solid solution series with arsenic bearing tennantite. Pure endmembers of the series are seldom if ever seen in nature. Of the two, the antimony rich phase is more common. Other elements also substitute in the structure, most notably iron and zinc along with less common silver, mercury and lead. Bismuth also substitutes for the antimony site and bismuthian

Tetrahedrite gets its name from the distinctive tetrahedron shaped cubic crystals. The mineral usually occurs in massive form, it is a steel grey to black metallic mineral with Mohs hardness of 3.5 to 4 and specific gravity of 4.6 to 5.2. It occurs in low to moderate temperature hydrothermal veins and in some contact metamorphic deposits. It is a minor ore of copper and associated metals. It was first

Malachite is a carbonate mineral, copper(II ) carbonate hydroxide Cu2CO3(OH)2. It crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses. Individual crystals are rare, but do occur as slender to acicular prisms. Pseudomorphs after more tabular or blocky azurite crystals also occur. Malachite often results from weathering of copper ores and is often found together with azurite (Cu3(CO3)2(OH)2), goethite, and calcite. Except for the vibrant green colour, the properties of malachite are very similar to those of azurite and aggregates of the two minerals together are frequently found,

The stone's name derives (via Latin and French) from Greek molochitis, "mallowgreen stone", from molochē, variant of malachē, "mallow". Malachite was used as a mineral pigment in green paints from antiquity until about 1800. The pigment is moderately lightfast, very sensitive to acids and varying in colour. The natural form was being replaced by its synthetic form, verditer amongst other synthetic greens. It is also used for decorative purposes, such as in the Malachite Room in the Hermitage which features a huge malachite vase. "The Tazza", one of the largest pieces of

Large quantities of malachite have been mined in the Urals. It is found in the Democratic Republic of Congo; Tsumeb , Namibia; Ural mountains, Russia; Mexico; Broken Hill, New South Wales; England; Lyon; and in the Southwestern United States especially in Arizona at Bisbee and Morenci. In Israel, malachite is extensively mined at Timna, often called King Solomon's Mines. Archeological evidence indicates that the mineral has been mined and smelted at the site for

PROCESS DIAGRAM

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The process of extracting copper from copper ore varies according to the type of ore and the desired purity of the final product. Each process consists of several steps in which unwanted materials are physically or chemically removed, and the concentration of copper is progressively increased. Some of these steps are conducted at the mine site itself, while others may be conducted at separate facilities.

Mining  1 Most sulfide ores are taken from huge open-pit mines by drilling and blasting with explosives. In this type of mining, the material located above the ore, called the overburden, is first removed to expose the buried ore deposit. This produces an open pit that may grow to be a mile or more across. A road to allow access for equipment spirals down the interior slopes of the pit.  2 The exposed ore is scooped up by large power shovels capable of loading 500-900 cubic feet (15-25 cubic meters)

Concentrating  The copper ore usually contains a large amount of dirt, clay, and a variety of non-copper bearing minerals. The first step is to remove some of this waste material. This process is called concentrating and is usually done by the flotation method.  3 The ore is crushed in a series of cone crushers. A cone crusher consists of an interior grinding cone that rotates on an eccentric vertical axis inside a fixed

4 The crushed ore is then ground even smaller by a series of mills. First, it is mixed with water and placed in a rod mill, which consists of a large cylindrical container filled with numerous short lengths of steel rod. As the cylinder rotates on its horizontal axis, the steel rods tumble and break up the ore into pieces about 0.13 in (3 mm) in diameter. The mixture of ore and water is further broken up in two ball mills, which are like a rod mill except steel balls are used instead of

5 The slurry is mixed with various chemical reagents, which coat the copper particles. A liquid, called a frother, is also added. Pine oil or long-chain alcohol are often used as frothers. This mixture is pumped into rectangular tanks, called flotation cells, where air is injected into the slurry through the bottom of the tanks. The chemical reagents make the copper particles cling to the bubbles as they rise to the surface.

The bubbles are allowed to condense and the water is drained off. The resulting mixture, called a copper concentrate, contains about 25-35% copper along with various sulfides of copper and iron, plus smaller concentrations of gold, silver, and other materials. The remaining materials in the tank are called the gangue or tailings. They are pumped into settling ponds and allowed to dry. Smelting  Once the waste materials have been physically removed from the ore, the remaining copper concentrate must undergo several chemical reactions to remove the iron and sulfur. This process is called smelting and traditionally involves two

6 The copper concentrate is fed into a furnace along with a silica material, called a flux. Most copper smelters utilize oxygenenriched flash furnaces in which preheated, oxygen-enriched air is forced into the furnace to combust with fuel oil. The copper concentrate and flux melt, and collect in the bottom of the furnace. Much of the iron in the concentrate chemically combines with the flux to form a slag, which is skimmed off the surface of the molten material. Much of the sulfur in the concentrate combines with the oxygen to form sulfur dioxide, which is exhausted

It is a mixture of copper sulfides and iron sulfides and contains about 60% copper by weight. 7 The molten matte is drawn from the furnace and poured into a second furnace called a converter. Additional silica flux is added and oxygen is blown through the molten material. The chemical reactions in the converter are similar to those in the flash furnace. The silica flux reacts with the remaining iron to form a slag, and the oxygen reacts with the remaining sulfur to form sulfur dioxide. The slag may be fed back into the flash furnace to act as a flux, and the sulfur dioxide is processed through

Refining  Even though copper blister is 99% pure copper, it still contains high enough levels of sulfur, oxygen, and other impurities to hamper further refining. To remove or adjust the levels of these materials, the blister copper is first fire refined before it is sent to the final electrorefining process.  8 The blister copper is heated in a refining furnace, which is similar to a converter described above. Air is blown into the molten blister to oxidize some impurities. A sodium carbonate flux may be added to remove traces of arsenic and antimony. A sample of the molten material is drawn and an experienced operator determines when the

9 Each copper anode is placed in an individual tank, or cell, made of polymer-concrete. There may be as many as 1,250 tanks in operation at one time. A sheet of copper is placed on the opposite end of the tank to act as the cathode, or negative terminal. The tanks are filled with an acidic copper sulfate solution, which acts as an electrical conductor between the anode and cathode. When an electrical current is passed through each tank, the copper is stripped off the anode and is deposited on the cathode. Most of the remaining impurities fall out of the copper sulfate solution and form a slime at the bottom of the tank. After about 9-15 days, the current is turned off and the cathodes are removed. The cathodes now weigh about 300 lb (136 kg) and are 99.95-99.99% pure copper.

Casting 11 After refining, the copper cathodes are melted and cast into ingots, cakes, billets, or rods depending on the final application. Ingots are rectangular or trapezoidal bricks, which are remelted along with other metals to make brass and bronze products. Cakes are rectangular slabs about 8 in (20 cm) thick and up to 28 ft (8.5 m) long. They are rolled to make copper plate, strip, sheet, and foil products. Billets are cylindrical logs about 8 in (20 cm) in diameter and several feet (meters) long. They are extruded or drawn to make copper tubing and pipe. Rods have a round cross-section about 0.5 in (1.3 cm) in

Leaching phase:  A leach pad or heap is sprinkled with an aqueous acidic solution.  In this schematic it is described as the acidified liquor spray.  This comes from the raffinate of the extraction stage(s).  The liquid passes through the heap, dissolving minerals along the way.  It is typically collected in a pond, which is affectionately called the pregnant leach solution or PLS. In-situ leaching  In-situ leaching is also called "solution mining." The process initially involves drilling of holes into the ore deposit. Explosives or hydraulic fracturing are used to create open pathways within the deposit for solution to penetrate into. Leaching

Heap leaching  In heap leaching processes, crushed (and sometimes agglomerated) ore is piled in a heap which is lined with an impervious layer. Leach solution is sprayed over the top of the heap, and allowed to percolate downward through the heap. The heap design usually incorporates collection sumps which allow the "pregnant" leach solution (i.e. solution with dissolved valuable metals) to be pumped for further processing. Dump leaching  Dump leaching combines characteristics of heap leaching and in-situ leaching. In a dump leach, an impervious layer may or may not be used depending on the dump

Vat leaching  Vat leaching involves contacting material, which has usually undergone size reduction and classification, with leach solution in large tanks or vats. Often the vats are equipped with agitators to keep the solids in suspension in the vats and improve the solid to liquid contact. After vat leaching, the leached solids and pregnant solution are usually separated prior to further processing. Other leaching techniques  In some cases, special leaching processes are required due to refractory nature of the material. These techniques include

After leaching, the leach liquor must normally undergo concentration of the metal ions that are to be recovered. Additionally, some undesirable metals may have also been taken into solution during the leach process. The solution is often purified to eliminate the undesirable components. The processes employed for solution concentration and purification include:  Precipitation  Cementation

Solvent extraction  A mixture of an extractant in a diluent is used to extract a metal from one phase to another. In solvent extraction this mixture is often referred to as the "organic" because the main constituent (diluent) is some type of oil.  The PLS (pregnant leach solution) is mixed to emulsification with the stripped organic and allowed to separate. The metal will be exchanged from the PLS to the organic. The resulting streams will be a loaded organic and a raffinate. When dealing with electrowinning, the loaded organic is then mixed to emulsification

The resulting streams will be a stripped organic and a rich electrolyte. The organic stream is recycled through the solvent extraction process while the aqueous streams cycle through leaching and electrowinning processes respectively. Ion exchange  Chelating agents, natural zeolite, activated carbon, resins, and liquid organics impregnated with chelating agents are all used to exchange

Metal recovery is the final step in a hydrometallurgical process. Metals suitable for sale as raw materials are often directly produced in the metal recovery step. Sometimes, however, further refining is required if ultra-high purity metals are to be produced. The primary types of metal recovery processes are electrolysis, gaseous reduction, and precipitation. Electrolysis  Electrowinning and electrorefining respectively involve the recovery and

Precipitation  Precipitation in hydrometallurgy involves the chemical precipitation of either metals and their compounds or of the contaminants from aqueous solutions. Precipitation will proceed when, through reagent addition, evaporation, pH change or temperature manipulation, any given species exceeds its limit of solubility. In order to improve efficiency in downstream processes, seeding to initiate crystallization is often used.

Extraction phase:  Through gravity or from the suction of the pumper mixer in the Extract Stage, PLS is mixed in a pump-box (mixer, pumper stage) with an organic solution often referred to as the barren organic (here called Regenerated Extractant coming from the Strip Stage) to form a liquid-liquid dispersion.  Mass transfer occurs and ideally only the desired mineral transfers selectively from the aqueous phase to the organic phase.  In this schematic, the mineral is copper.

In most SX plants, there is usually a pumpbox followed by one or more auxiliary mixing tanks.  Their purpose is to maintain the dispersion and give more residence time for the extraction to take place.  Then the dispersion is sent to a settler, where the two phases disengage.  The lighter fluid (organic) is removed from the top, while the heavier fluid (aqueous phase) is removed from the bottom of the end of the settler.  The aqueous is now called raffinate and is returned to the heap or leach pad.  It contains lots of dissolved minerals, but very little of the desired mineral.  The

Stripping phase:  The loaded organic extractant is mixed with the aqueous lean electrolyte (hear strip solution) to form another liquid-liquid dispersion.  Due to a shift in pH, the desired mineral transfers back from the organic phase to the aqueous phase.  Once again, it is not unusual to find one pump-box followed by one or more auxiliary mixing tanks to achieve the desired residence time and mass transfer efficiency.  The dispersion is again sent to a settler so that the two liquid phases can be separated again.  A portion of the aqueous phase, called here the Concentrated Copper Electrolyte, is pumped to the Electrowinning house, while the rest is recycled back to the Strip Stage Pure copper (desired purity is called five-nines = 99.999%) is deposited on plates, pulling the copper out of solution.  This solution is called the lean

This method almost doubles the throughput of copper, because E1P (or E3(P)) replaces the former S2 allowing essentially twice the copper to be processed.  Although the single stage E1P will not have the same transfer efficiency as the dual stage E1-E2, the copper remaining in the raffinate goes back to the pad and will eventually come back to the plant to be processed another day.  Regardless of the SX circuit layout, each stage is treated in the same way with CFD.  The only difference is the density (and other properties) and flow rates through each stage.  E1 and S1 are often

POLLUTION AND ABATEMENT

Byproducts/Waste The recovery of sulfuric acid from the copper smelting process not only provides a profitable byproduct, but also significantly reduces the air pollution caused by the furnace exhaust. Gold, silver, and other precious metals are also important byproducts.

Waste products include the overburden from the mining operation, the tailings from the concentrating operation, and the slag from the smelting operation. This waste may contain significant concentrations of arsenic, lead, and other chemicals, which pose a potential health hazard to the surrounding area. In the United States, the Environmental Protection Agency (EPA) regulates the storage of such wastes and the remediation of the area once mining and processing operations have ceased. The sheer volume of the material involved—in some cases, billions of tons of waste—