A TERM PAPER ON HISTORICAL METTALLURGICAL PROCESS IN NIGERIA IN PARTIAL FUFILLMENT OF THE AWARDING OF A BACHELOR’S DEGREE
DEPARTMENT OF MECHANICAL ENGINNEERING
SUBMITTED TO: A.A. ADEDIRAN
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Metallurgy can be defined as the art and science of extracting metals from their ores and modifying the metals for use. Metallurgy customarily refers to commercial as opposed to laboratory methods. It also concerns the chemical, physical, and atomic properties and structures of metals and the principles whereby metals are combined to form alloys. Metallurgy is also the technology of metals; the way in which science is applied to the production of metals, and the engineering of metal components for usage in products for manufacturers and consumers. The production of metals involves the processing of ores to extract the metal they contain, and the mixture of metals, in some occasions with other elements, to produce alloys. The science of metallurgy is subdivided into physical metallurgy and chemical metallurgy.
Branches of metallurgy are physical metallurgy which involves the physical properties of metals, mechanical metallurgy which involves the mechanical properties of metals and foundry engineering which involves molding and casting of metals and non-metals into dimensions, shapes and size, Heat technology which includes heat treatment of metals, Extractive Metallurgy which involves chemical and thermodynamics principles.
The history of metallurgical processes in Nigeria is relevant in the view of various historical invents as no substance has been as important as metal in the story of man’s control of his environment. Advances in agriculture, warfare, transport, even cookery are impossible without metal. The present-day use of metals is the result of a long path of development extending over approximately 6,500 years. It is generally agreed that the first known metals were gold, silver, and copper, which occurred in the native or metallic state, of which the earliest were in all probability nuggets of gold found in the sands and gravels of riverbeds. Such native metals became known and were appreciated for their ornamental and utilitarian values during the latter part of the Stone Age. The early development in the history of metallurgy is going to be emphasized on before the history of metallurgy in Nigeria.
HISTORY OF METALLURGY
The earliest recorded metal employed by humans is gold, which can be found free or native. Gold, the most attractive and precious of metals in every society, is also the easiest for primitive man to acquire. Gold is bright, incorruptible, malleable, and appears in pure form in the beds of streams. Once seen, acquiring it is just a matter of picking it up. Pure gold also has the quality of softness. It can be easily shaped by hammering, but this malleability makes it useless for practical purposes. It begins as it has continued, a luxury item.
The earliest surviving gold Jewelry is from Egypt in about 3000 BC. Small amounts of natural gold have been found in Spanish caves used during the late Paleolithic period, c. 40,000 BC. Silver, copper, tin and meteoric iron can also be found in native form, allowing a limited amount of metalworking in early cultures. Egyptian weapons made from meteoric iron in about 3000 BC were highly prized as daggers from heaven.
Certain metals, notably tin, lead and (at a higher temperature) copper, can be recovered from their ores by simply heating the rocks in a fire or blast furnace, a process known as smelting. The first evidence of this extractive metallurgy, dating from the 5th and 6th millennia BC, has been found at archaeological sites in Majdanpek, Yarmovac, and Plocnik, in present-day Serbia. To date, the earliest evidence of copper smelting is found at the Belovode site near Plocnik. This site produced a copper axe from 5500 BC, belonging to the Vin?a culture.
The earliest use of lead is documented from the late Neolithic settlement of Yarim Tepe in Iraq,
The earliest lead finds in the ancient Near East are a 6th millennium BC bangle from Yarim Tepe in northern Iraq and a slightly later conical lead piece from Halaf period Arpachiyah, near Mosul. As native lead is extremely rare, such artifacts raise the possibility that lead smelting may have begun even before copper smelting.
By that time people have long discovered an everyday use for another metal which exists in nature in a pure form, and which can also be bashed into new shapes with less ease than gold, for it is much harder, but with more practical results. This metal is copper.
Gold can be agglomerated into larger pieces by cold hammering, but native copper cannot, and an essential step toward the Metal Age was the discovery that metals such as copper could be fashioned into shapes by melting and casting in molds; among the earliest known products of this type are copper axes cast in the Balkans in the 4th millennium BCE. Another step was the discovery that metals could be recovered from metal-bearing minerals. These had been collected and could be distinguished on the basis of colour, texture, weight, and flame colour and smell when heated. The notably greater yield obtained by heating native copper with associated oxide minerals may have led to the smelting process, since these oxides are easily reduced to metal in a charcoal bed at temperatures in excess of 700 °C (1,300 °F), as the reductant, carbon monoxide, becomes increasingly stable. In order to effect the agglomeration and separation of melted or smelted copper from its associated minerals, it was necessary to introduce iron oxide as a flux. This further step forward can be attributed to the presence of iron oxide gossan minerals in the weathered upper zones of copper sulfide deposits.
Copper smelting is also documented at this site at about the same time period (soon after 6000 BC), although the use of lead seems to precede copper smelting. Early metallurgy is also documented at the nearby site of Tell Maghzaliyah, which seems to be dated even earlier, and completely lacks pottery.
Other signs of early metals are found from the third millennium BC in places like Palmela (Portugal), Los Millares (Spain), and Stonehenge (United Kingdom). However, the ultimate beginnings cannot be clearly ascertained and new discoveries are both continuous and ongoing.
In the Near East, about 3500 BC, it was discovered that by combining copper and tin, a superior metal could be made, an alloy called bronze. This represented a major technological shift known as the Bronze Age.
The extraction of iron from its ore into a workable metal is much more difficult than for copper or tin. The process appears to have been invented by the Hittites in about 1200 BC, beginning the Iron Age. The secret of extracting and working iron was a key factor in the success of the Philistines.
Historical developments in ferrous metallurgy can be found in a wide variety of past cultures and civilizations. This includes the ancient and medieval kingdoms and empires of the Middle East and Near East, ancient Iran, ancient Egypt, ancient Nubia, and Anatolia (Turkey), Ancient Nok, Carthage, the Greeks and Romans of ancient Europe, medieval Europe, ancient and medieval China, ancient and medieval India, ancient and medieval Japan, amongst others. Many applications, practices, and devices associated or involved in metallurgy were established in ancient China, such as the innovation of the blast furnace, cast iron, hydraulic-powered trip hammers, and double acting piston bellows.
A 16th century book by Georg Agricola called De re metallica describes the highly developed and complex processes of mining metal ores, metal extraction and metallurgy of the time. Agricola has been described as the “father of metallurgy”.
The age of copper: from 7000 BC
From about 7000 BC a few Neolithic communities begin hammering copper into crude knives and sickles, which work as well as their stone equivalents and last far longer. Some of the earliest implements of this kind have been found in eastern Anatolia. This intermediate period between the Stone Age (when all weapons and tools are of flint) and the first confident metal technology (the Bronze Age) has been given a name deriving from the somewhat awkward combination of materials. It is called the Chalcolithic Period, from the Greek chalcos ‘copper’ and lithos ‘stone’. An accident, probably frequent, reveals another of nature’s useful secrets. A nugget of pure copper, or perhaps a finished copper tool, falls into the hot camp fire. The copper melts. When it cools, it is found to have solidified in a new shape. And the magic of fire has yet more to offer. Certain kinds of bright blue or green stones are attractive enough to collect for their own sake. It turns out that when such stones are heated to a high temperature, liquid metal flows from them. They are azurite and malachite, two of the ores of copper. The use of fire thus makes possible two significant new steps in the development of metallurgy: the casting of metal, by pouring it into prepared molds; and the smelting of mineral ores to extract metal. Objects made from smelted copper, from as early as 3800 BC, are known in Iran. Many mineral ores are found on the surface of the earth, in outcrops of rock. Chipping away at them, to pursue the metal-bearing lode down below the surface, leads inevitably to another technological advance hence the development of mining.
The first miners: from 4000 BC
By 4000 BC deep shafts are cut into the hillside at Rudna Glava, in the Balkans, to excavate copper ore. This robbing of the earth’s treasures is carried out with due solemnity. Fine pots, bearing produce from the daylight world, are placed in the mines as a form of recompense to propitiate the spirits of the dark interior of the earth. By about 3800 BC copper mines are also worked in the Sinai Peninsula. Crucibles found at the site reveal that smelting is carried out as part of the mining process.
The age of bronze: from 2800 BC
Sometimes the ores of copper and tin are found together, and the casting of metal from such natural alloys may have provided the accident for the next step forward in metallurgy. It is discovered that these two metals, cast as one substance, are harder than either metal on its own. The cast alloy of copper and tin is bronze, a substance so useful to human beings that an entire period of early civilization has become known as the Bronze Age. A bronze blade will take a sharper edge than copper and will hold it longer. And bronze ornaments and vessels can be cast for a wide variety of purposes. The figure of a bronze blade is seen below as figure 1.1;
The cast alloy of copper and tin is bronze, a substance so useful to human beings that an entire period of early civilization has become known as the Bronze Age. A bronze blade will take a sharper edge than copper and will hold it longer. And bronze ornaments and vessels can be cast for a wide variety of purposes. The technology of bronze is first developed in the Middle East. Bronze is in use in Sumer, at Ur, in around 2800 BC, and in Anatolia shortly afterwards. It then spreads spasmodically. It appears in the Indus valley in about 2500 BC, and progresses westwards through Europe from about 2000. At much the same time it is found in crude form in China, where it later achieves an unprecedented level of sophistication. From about 1500 BC the Shang dynasty produces bronze objects of exceptional brilliance.
The age of iron: from 1500 BC
The next great development in metallurgy involves a metal which is the most abundant in the earth’s surface but which is much more difficult to work than copper or tin. It is iron, with a melting point too high for primitive furnaces to extract it in pure form from its ore. The best that can be achieved is a cluster of globules of iron mixed with sludgy impurities. This unpromising substance can be turned into a useful metal by repeated heating and hammering, until the impurities are literally forced out. A few iron objects dating from before 2000 BC have been found (beads, a ring, some blades), but it is not until about 1500 BC that the working of iron is done anywhere on a regular basis.
It is not possible to mark a sharp division between the Bronze Age and the Iron Age. Small pieces of iron would have been produced in copper smelting furnaces as iron oxide fluxes and iron-bearing copper sulfide ores were used. In addition, higher furnace temperatures would have created more strongly reducing conditions (that is to say, a higher carbon monoxide content in the furnace gases). An early piece of iron from a trackway in the province of Drenthe, Netherlands, has been dated to 1350 BC, a date normally taken as the Middle Bronze Age for this area. In Anatolia, on the other hand, iron was in use as early as 2000 BC.
There are also occasional references to iron in even earlier periods, but this material was of meteoric origin.
Another iron-making region, the Catalan forge had been invented, and its use later spread to other areas. A hearth type of furnace, it was built of stone and was charged with iron ore, flux, and charcoal. The charcoal was kept ignited with air from a bellows blown through a bottom nozzle, or tuyere (see figure 1.2 below). The bloom that slowly collected at the bottom was removed and upon frequent reheating and forging was hammered into useful shapes.
By the 14th century the furnace was greatly enlarged in height and capacity.
Catalan hearth or forge used for smelting iron ore until relatively recent times. The method of charging fuel and ore and the approximate position of the nozzle supplied with air by a bellows are shown.
The discovery of steel: 11th century BC
By the 11th century BC it has been discovered that iron can be much improved. If it is reheated in a furnace with charcoal (containing carbon), some of the carbon is transferred to the iron. This process hardens the metal; and the effect is considerably greater if the hot metal is rapidly reduced in temperature, usually achieved by quenching it in water. The new material is steel. It can be worked (or ‘wrought’) just like softer iron, and it will keep a finer edge, capable of being honed to sharpness. Gradually, from the 11th century onwards, steel replaces bronze weapons in the Middle East, birthplace of the Iron Age. It becomes essential, from now on, to have a good steel blade rather than a soft and indifferent one.
Cast iron in the east: 513 BC
Thus far in the story iron has been heated and hammered, but never melted. Its melting point (1528°C) is too high for primitive furnaces, which can reach about 1300°C and are adequate for copper (melting at 1083°C). This limitation is overcome when the Chinese develop a furnace hot enough to melt iron, enabling them to produce the world’s first cast iron – an event traditionally dated in the Chinese histories to 513 BC. In this they are a thousand and more years ahead of the western world. The first iron foundry in England, for example, dates only from AD 1161. By that time the Chinese have already pioneered the structural use of cast iron, using it sometimes for the pillars of full-size pagodas.
HISTORY OF METALLURGY IN NIGERIA
History of metallurgical processes began as early as early Nigerian cultures such as;
The Nok culture
Evidence of human occupation in Nigeria dates back thousands of years. The oldest fossil remains found by archaeologists in the southwestern area of Iwo Eleru, near Akure, have been dated to about 9000 BC. There are isolated collections of ancient tools and artifacts of different periods of the Stone Age, but the oldest recognizable evidence of an organized society belongs to the Nok culture (c. 500 BC–c. 200 C).
Named for the village of Nok, site of some of the finds, the ancient culture produced fine terra-cotta figurines, which were accidentally discovered by tin miners on the Jos Plateau in the 1930s. Initially Neolithic (New Stone Age), the Nok culture made the transition to the Iron Age. Its people raised crops and cattle and seem to have paid particular attention to personal adornment, especially of the hair. Distinctive features of Nok art include naturalism, stylized treatment of the mouth and eyes, relative proportions of the human head, body, and feet, distortions of the human facial features, and treatment of animal forms. The spread of Nok-type figures in a wide area south of the Jos Plateau, covering southern Kaduna state southeastward to Katsina Ala, south of the Benue River, suggests a well-established culture that left traces still identifiable in the lives of the peoples of the area today. Many of the distinctive features of Nok art can also be traced in later developments of Nigerian art produced in such places as Igbo Ukwu, Ife, Esie, and Benin City.
Pottery head found at Nok, in the Jos museum, Nigeria, Height 21m is found below figure 1.3;
Bronzes, which have been dated to about the 9th century, were discovered in the 1930s and ’40s at Igbo Ukwu, near the southwestern city of Onitsha. (See also African art.) They reveal not only a high artistic tradition but also a well-structured society with wide-ranging economic relationships. Of particular interest is the source of the copper and lead used to make the bronzes, which may have been Tadmekka in the Sahara, and of the coloured glass beads, some of which may have come from Venice and India, the latter via trade routes through Egypt, the Nile valley, and the Chad basin. It is believed that the bronzes were part of the furniture in the burial chamber of a high personage, possibly a forerunner of the eze nri, a priest-king, who held religious but not political power over large parts of the Igbo-inhabited region well into the 20th century.
Kingdoms and empires of precolonial Nigeria
Many indigenous polities emerged in Nigeria before the British took control in the late 19th century. In the north there were several large and developed systems, including the Hausa states of Kano, Katsina, Zaria, and Gobir; Kanem-Borno; and the Jukun states of Kwararafa, Kona, Pinduga, and Wukari. Smaller kingdoms included those of the Igala, Nupe, and Ebira. Notable in the south were the Yoruba states of Ife and Oyo, the Edo state of Benin, the Itsekiri state of Warri, the Efik state of Calabar, and the Ijo (Ijaw) city-states of Nembe, Elem Kalabari, Bonny, and Okrika.
The history of Borno antedates the 9th century, when Arabic writers in North Africa first noted the kingdom of Kanem, east of Lake Chad. The lake was then much larger than the present-day body of water, and its basin attracted settlements and encouraged exchange. A pastoral group, ancestors of the Kanuri, established a centralized state over those referred to collectively as the Sao. Initially, trading links extended to the Nile valley of Egypt. There is some evidence that Kanem had made contact with the Christian kingdoms of Nubia before it was overrun by Muslims, who gained a foothold in the ruling family of Kanem in the 11th century. From Kanem the rulers tried to dominate the areas south and west of the lake as well. By the 12th century they had been compelled by attacks from the Sao to move their capital to the region west of Lake Chad, and they gradually lost control of most of the original Kanem.
For a long time, Borno was the dominant power in the central Sudan, including much of Hausaland. The Bayajidda legend, concerning a mythical Middle Eastern ancestor of the Hausa, seems to suggest that the rise of a centralized political system in Hausaland was influenced from Borno. Though the rulers of Borno embraced Islam, the structure of the monarchy remained traditional, with the queen mother and other female officials exercising considerable power. The selection of the monarch, the coronation rites, and other bases of royal authority were dictated by pre-Islamic beliefs. The princes and other members of the royal family were granted fiefs and posted away from the capital to govern frontier zones, while people of slave origin were preferred for the royal guard and palace officials.
For centuries the Hausa have occupied the northern plains beyond the Jos Plateau, which were a crossroads open not only to Borno but also to the states of Mali and Songhai in the western Sudan, the trans-Saharan routes to northern Africa, and various trade routes to the forest areas of Borgu, Oyo, and Benin. Perhaps because of this strategic location, the Hausa developed a number of centralized states—such as Daura, Katsina, Kano, Zaria, Gobir, and, later, Kebbi each with a walled city, a market center, and a monarchical system of government. Islam, which was introduced from the Mali empire in the 14th century, strengthened both the monarchical system and the commercial contacts, but it remained predominantly an urban religion until the beginning of the 19th century. Even within the walled cities, however, some pre-Islamic rites remained part of the ceremonies that sustained monarchical authority. A considerable rivalry existed between the different states over agricultural land and the control of trade and trade routes, and Hausaland was periodically conquered by powerful neighbors such as Borno and Songhai.
Yorubaland and Benin
Ife, which flourished between the 11th and 15th centuries, emerged as a major power in the forested areas west of the Niger and south of Hausaland. Some of the characteristic features of Yoruba culture emerged during that time: a monarchical system based on city-states and nucleated villages; a pantheon of gods, a few of which were recognized widely but with several local variations; and divination centered on the deity Ifa, with its corpus of sacred chants. Ife is best known for its potsherd pavements and for the great artistry of its terra-cottas and bronzes, especially the naturalism of many of its bronze figures. (See also African art.) Ife’s influence on surrounding states is evident in the fact that all the monarchies of Yoruba states claim descent from Ife as a way of establishing legitimacy, sometimes borrowing regalia from Ife to use in coronation rites and sometimes sending remains of deceased rulers to Ife for burial.
Oyo, founded in the 14th century and located in the savanna to the north of the forest, gradually supplanted the older kingdom of Ife. After more than a century of struggle with nearby Borgu and Nupe, it established itself strategically as the emporium for exchanging goods from the north—rock salt, copper, textiles, leather goods, and horses—with products from the south—kola nuts, indigo, parrots, and cowries. By the 17th century it had built up a cavalry force with which it dominated people in western Yorubaland and in the dry gap to the coast; to the south, infestations of tsetse flies prevented kingdoms there from effectively utilizing horses.
When the Portuguese arrived in the kingdom of Benin in the 15th century, they found a monarchy, dating back many centuries, with a complex structure of chiefs and palace officials presiding over a kingdom that was expanding in all directions. In time, Benin dominated not only the Edo-speaking peoples to the north and south but also the area eastward to the Niger and, along the coast, to Lagos (which the Edo now claim to have founded) and even into present-day Ghana. It also exerted considerable influence on eastern Yorubaland and maintained trading connections with Oyo. Benin art, which began to flourish in the 15th century, was characterized by naturalistic bronze sculptures and bronze door panels that covered the outside of the royal palace.
Portuguese explore or trader; plaque depicting a Portuguese explore or trader, from Nigeria, in the Brooklyn museum, New York.
The 21st century has seen metallurgy change progressively, from an art or craft to a scientific discipline and then to part of the wider discipline of materials science. In extractive metallurgy, there has been the application of chemical thermodynamics, kinetics, and chemical engineering, which has enabled a better understanding, control, and improvement of existing processes and the generation of new ones. In physical metallurgy, the study of relationships between macrostructure, microstructure, and atomic structure on the one hand and physical and mechanical properties on the other has broadened from metals to other materials such as ceramics, polymers, and composites.
James A. Charles, Clarence H. Lorig, Charles Burroughs Gill, Paul G. Shewmon.
Arthur Reardon (2011), Metallurgy for the Non-Metallurgist (2nd edition), ASM International, ISBN 978-1-61503-821-3
Oxford English Dictionary, accessed 29 January 2011
“???????????”. in The Great Soviet Encyclopedia. 1979
R. F. Tylecote (1992) A History of Metallurgy ISBN 0-901462-88-8
Moorey 1994: 294
Craddock 1995: 125
A, A Adediran