The riches of the Copper Belt in Katanga, Belgian Congo, and of the copper mines in Northern Rhodesia have been won by the efforts of explorers, railway pioneers and mining engineers, who have built up an important industry in a district remote from the rest of civilization
THE N’KANA COPPER MINE, in Northern Rhodesia, consists of a vertical central hoisting shaft more than 1,000 feet deep and a smaller but deeper vertical shaft for advance work. Adjoining the central shaft are the buildings, shown above, which house the concentrator and the crushers. The concentration process separates the copper from worthless matter.
COPPER is the metal prehistoric man first used to serve his primitive needs. Although iron and steel overshadowed copper from the Middle Ages onwards, the birth of the electrical age renewed its importance. To-day copper enters into almost every department of engineering, either as pure copper or in alloys such as bronze, brass, gunmetal, Muntz metal, aluminium bronze and nickel silver. It is essential for electrical manufactures, telephone, telegraph, light and power lines, wire and wire products, motor cars, buildings, castings, radio, refrigerators and other products.
Tubes and electric railways, power plants and grid systems, and ammunition all need copper. The towering giants of the ether which pierce the low-lying clouds exalt copper. Copper carries the thoughts of man under the sea from continent to continent. Hundreds of millions of miles of copper wire carry the spoken word and the dots and dashes of the Morse code over and under the earth. The huge hydroelectric and steam power generating stations would be powerless but for the virtues of copper. Except for silver, the price of which would be prohibitive, copper is the best carrier of electricity and will conduct five and three-quarter times the current an iron wire of the same diameter would carry. It can be drawn into wire of the fineness of one thousandth of an inch diameter; in a 1,200 pair cable there are 2,400 copper wires, and yet the diameter of the cable is only 2½ in. Copper is so malleable that it can be beaten out into thin sheets. Its resistance to corrosion is of great value; a coat of green carbonate forms on the surface of exposed copper and protects it so that it outlasts ordinary steel and iron and does not need constant painting. Its capacity for conducting heat is used in marine and other boiler tubes. It is an easy mixer; alloyed with tin it forms bronze, and with zinc, brass.
The metal is called copper because the ore was obtained from the island of Cyprus in the Mediterranean. Copper-bearing minerals are widely distributed and are found in almost all countries although not always in quantities that would make the mining and treatment of the ores commercially profitable. Occasionally “native” copper - copper uncombined with another element - is found in small quantities, but the bulk of the metal has to be extracted from the ore by huge plants. In the past large supplies of native copper have been extracted from the Lake Superior deposits in the north of the State of Michigan, but the days of finding masses of copper weighing up to 500 tons are over. Such purity is essential for copper intended for electrical purposes that native copper is refined by electrolysis.
The properties of copper made electricity the servant of man, and the development of electricity in turn increased the demand for copper. The prospector, the mining engineer and the metallurgist rose to the occasion, and, supported by armies of auxiliaries, they have changed the face of the earth in many countries. The greatest change of all has taken place in recent years in what is now called the Copper Belt in the heart of Africa. In what was once “Darkest Africa” are towns with factories, hospitals, cinemas and shops, lighted with electricity generated by hydro-electric power stations; the area is served by railways from the Indian Ocean to the Atlantic, by air lines and by steamers.
Ports have been built at the ocean terminals of the railways, and ships carry the copper to the markets of the world. Millions of pounds have been spent and engineers from all parts of the world have effected this transformation - all because of copper. Not many years ago the explorer-prospector penetrated into this country at the risk of his life in search of copper. Nowadays the first stage is to build an airport, and landing fields, spaced at twenty-miles intervals, to provide against accidents. Then the procedure is to map and survey a new district from the air with a camera.
The Copper Belt extends for about 250 miles with an average width of about fifty miles in the Katanga Province of Belgian Congo.
South of the belt, in Northern Rhodesia, are the mines in British territory. The mines in the Katanga are richer in copper content, and only in the last ten years or so have those on the Rhodesian side been developed extensively.
The early Portuguese and adventurers of various nations who searched for minerals in south central Africa were so obsessed by the quest for gold and silver that they remained ignorant of the Copper Belt, although large quantities of copper were mined and smelted in a primitive way by natives enslaved by Arabs. The copper was smelted into ingots in the shape of a cross and was used for barter. The primitive industry survives in a few places in the Congo, and links the past with the present era of huge mines, blast furnaces and modern electrical processes.
In the last century several explorers mentioned copper. Commander Cameron,who crossed Africa from east to west in the ’seventies, referred to copper at Katanga and to the westward. Dr. George Schweinfurth referred to the Copper Belt, but was doubtful about its locality. In the ’eighties, P. Reichard, a German, brought back particulars of two deposits, one of which became the Luishia Mine. Then further evidence was found, and in the ’nineties the quest began in earnest.
Two world figures, Cecil Rhodes and King Leopold, now enter the story. Rhodes’s men were working up towards the Copper Belt from the south and south-east, and Leopold’s emissaries were thrusting down from the north.
Captain Stairs, a Briton, was in command of the expedition sent by Leopold. He entered the Katanga, and after an encounter in which a slave trader who had set up as king of the district was killed, annexed the Katanga for the Congo. A later Belgian expedition included a geologist who found copper at Kambove and elsewhere.
Meanwhile, the agents of Rhodes secured mining and other rights in what is now Rhodesia, and the rails of Rhodes’s projected Cape to Cairo Railway crept north. Various expeditions were made to find minerals with the object of creating traffic which would make the railway pay. Sir (then Mr.) Robert Williams sent Mr. George Grey on one expedition in 1895, which failed to locate minerals, and then again in 1899.
The 1899 expedition set out from the railhead at Bulawayo on what was one of the most successful prospecting ventures ever made. Grey went about 1,000 miles into the great divide between the headwaters of the Congo and the Zambezi. A native showed Grey the old workings of the Kansanshi Mine, from which he and his fellow tribesmen had collected bits of ore. On Grey went into the Katanga, prospecting through field-glasses which showed that every hillock bare of vegetation was a potential copper mine.
THE KATANGA COPPER BELT is one of the richest natural deposits of copper-bearing ore in the world. The discovery of coalfields at Wankie, to the north-west of Bulawayo, in Southern Rhodesia, made possible the opening up of the copper areas on the borders of Belgian Congo and Northern Rhodesia. The railway was pushed forward to link Katanga with Salisbury, capital of Southern Rhodesia, and with the port of Beira on the Indian Ocean. Later railway connexion was established with Benguela and Lobito, on the Atlantic coast of Angola.
Sir Robert Williams, who was convinced that Grey would find the copper in the Katanga, had already secured a concession from the King of the Belgians and had formed a company called Tanganyika Concessions, Ltd. When Grey returned another expedition was sent out. Later, an American mining expert, Mr. R. J. Farrell, made a detailed survey, and his report on the extent and richness of the deposits was criticized by one expert as “geological delirium tremens”, but other surveys confirmed its accuracy.
Despite this, however, most people considered that the remoteness of the area, the lack of transport, difficulties in the treatment of the ore and the apparent impossibility of getting adequate plant into the heart of Africa made the discovery interesting but not a practical proposition. They did not realize the steady purpose of the pioneers, the determination of railway engineers, improvements in refining and the fact that an extensive coalfield existed, not adjacent to the copper, it is true, but within reach if a railway were built.
The discovery of the coalfield which made possible the opening up of the Copper Belt is a romance in itself, and caused Rhodes to alter the route of his projected Cape to Cairo Railway. The name of the Wankie coalfield is a corruption of “Zankie”, the title of the chief of the Abananzwa tribe, who had been harried by the Matabeles. Having heard that their oppressors, the Matabeles, had been defeated by the white men, the tribe sent messengers to the post at Tati, Bechuanaland, with two elephant tusks as a present. The envoys told the white men that in their country they found black stones which burned. One of the whites, Mr. A. Giese, set out with an expedition to investigate the story. After many adventures with the Matabeles, he reached Wankie in 1895, prospected and took samples of the coal to Bulawayo.
Years elapsed before the railway reached the coalfield and mining began in earnest. The great barrier of the Victoria Falls was bridged, as described in the chapter beginning on page 411, and the coal was carried to the Copper Belt. At one time over a million tons of coal were mined every year. Other coalfields exist in Northern Rhodesia and in Belgian Congo, but as yet the Rhodesian coalfields are undeveloped.
Mining engineers and experts from copper mines and smelting works in all parts of the world arrived in the Copper Belt, millions of pounds of capital were spent not only on the equipment of the mines but also on the railways, and the first stage of the conquest of the heart of south central Africa began.
Copper mining began to get into its stride when the last section of the railway linking Elisabethville, the capital of the Kantanga Province, with the railways of Rhodesia was completed in 1910. This gave an outlet for the copper to the port of Beira, on the Indian Ocean. Later, the Benguela Railway was built across Africa to the west coast and a port was built at Lobito. Railways to by-pass the cataracts of the River Congo were built to form a chain of transport linking with the river steamers. River, lake and railway transport also afford outlets to the ports of Mombasa and Dar es Salaam, on the Indian Ocean.
THE ETOILE MINE, or “Star of the Congo,” near Elisabethville, Belgian Congo, was worked continuously until 1926, when the workings were abandoned because the richer deposits had been by that time extracted. For years this mine and the Kambove Mine were responsible for the bulk of the production in the district.
Before the rails reached the mines the engineers were ready. The first copper to be produced came from the Kansanshi mines on the Northern Rhodesian side of the border, and when the railway arrived in 1910 metal valued at £170,000 was loaded on to the wagons. The Etoile Mine, “the Star of the Congo”, was opened near Elisabethville and was worked continuously until 1926, when production ceased as the richer deposits had been extracted. This mine and the Kambove Mine were for years responsible for the bulk of the production in the region. In 1922 the Ruashi Mine was opened near the Etoile. In 1926 the Ivipushi Mine, afterwards renamed the Prince Leopold Mine, which contains an exceptionally rich sulphide ore, was opened. The mine is twenty-three miles south-west of Elisabethville. The ore is so valuable that part of it has been sent direct to Europe for smelting.
On the Northern Rhodesian side of the border important developments have taken place, particularly in the last decade. In 1923 was initiated a system of granting exclusive prospecting rights to syndicates. On the average the value of a ton of this ore is less than that in the Katanga, but technical problems have been solved by the installation of plant which is the last word in efficiency.
Forest, dense vegetation and overburden concealed the outcrop, and the surveying of a large region was a feat in itself. One concession covered 52,000 square miles, and a large part of this was mapped and surveyed from the air. To enable this to be done two large airports were built. Dense growth had to be rooted up and giant anthills levelled. A chain of smaller landing fields was built at intervals of twenty miles in the bush to safeguard the airmen against forced landings. Motor roads were built, camps established and supply services set up. In the Katanga the oxide ores were near the surface, in shallow deposits which were the first to be worked. Later the sulphide ores were found at greater depths by boring, and these were developed. There is a large concentrator, with an electrolytic plant, at Jadotville: the smelter is at Lubumbashi, a suburb of Elisabethville. Some of the mines are open workings; others have been opened by a large main vertical shaft and a series of subsidiary incline shafts. In the open mines steam shovels have been used largely, but many of these have been replaced by electric shovels.
In Rhodesia the equipment of the mines is huge. The main shaft of the Roan Antelope mines is called the Beatty Shaft. The total height of the steel head frame, from the foundations to the top of the poppet frame, is 189 feet. The shaft is of six compartments.
The general principle in shaft mines is a system of sub-level open mining, in which pillars of ore are used for support. As the shaft reaches the necessary depth horizontal main transport levels are driven parallel with the ore body. The ore is hauled along these levels in trains of 10-tons trucks by electric locomotives to the main winding shaft, where the trucks are tipped and loaded into 10-tons skips for hoisting to the surface.
When Copper Floats
The interval between the two main haulage levels is divided into blocks by raises, from which small sub-levels are driven at intervals. Broken ore falls to chutes at the haulage level. In steep slopes the broken rock falls by itself, but when the dip is not steep enough the ore is brought to the loading chute by power-driven scrapers. This method avoids the use of timber, and its simplicity is a considerable advantage, as the miners are inexperienced natives.
The copper in south central Africa is obtained from oxide ores and sulphide ores, and the first stage in the chain of processes is to separate the copper from worthless matter by a concentration process. The concentration processes differ according to the nature of the ore. First the ore is crushed into small pieces and ground to a fine powder. With some ore, concentration is by gravity. The powder is mixed with water and the mixture passes over vibrating tables which shake the valuable matter to one side while the lighter and worthless matter is washed away to be treated again if necessary, and finally sent to the tailings dump.
STEAM SHOVEL at work in the Chituru Mine, near Jadotville, in the Katanga Province of Belgian Congo. In many instances electric shovels have replaced steam shovels in open workings, because hydro-electric schemes have made ample electric power available.
Sulphide ores are treated by the flotation process of concentration, the efficiency of which has made possible the mining of the low copper-content ores of Rhodesia. It is based upon the peculiarity of certain minerals to become coated with a film of oil when the crushed ore is agitated in a vat of water to which a frothing oil is added. Air bubbles form on the particles of copper and cause them to float in a scum on the surface, while the worthless matter remains suspended in the water.
The concentrate is sent to reverberatory furnaces and smelted with the addition of fluxes to what is known as a matte. The slag is discarded, and the matte, consisting mostly of copper and sulphur, is transferred in a molten state to the converter, a pear-shaped steel vessel lined with firebrick, with holes in the base through which air is blown. The air oxidizes the sulphur, which goes off as sulphur dioxide, leaving molten copper. This is cast into cakes and is known as blister copper because of the rough surface caused by the escape of dissolved oxygen at the moment of solidification. This blister copper is further refined either by remelting in a small reverberatory furnace, where the oxygen and small quantities of other impurities are removed, or by electrolytic refining.
Electrolytic refining is essential if the copper is to be of the purest grade suitable for electric work. The fire-refined copper is cast into flat bars. These form the anodes or positive poles of the depositing bath and are immersed in acid.
The acid dissolves the copper and as a current is passed through the solution to the cathode - a thin sheet of copper forming the negative pole - the dissolved copper is deposited on it. Impurities sink as a black slime, which is treated for the recovery of the precious metals it contains. The cathode copper is melted and cast into bars of electrolytic copper, the purest copper of all.
25,000,000 Tons of Ore
Electrolytic plant, furnaces, mines and all the machinery which converts ore into copper ingots are in operation in the middle of Africa. There are power plants, factories and distribution agencies for the supply of electricity, chemicals, cement, engineering materials and food. The concentrating plant of the Union Miniere and the reverberatory furnaces are at Jadotville, where are the electrolytic works referred to above.
At Lubumbashi, there are water-jacket furnaces and an electric power plant with a turbo-alternator group of 5,000 kilowatts. At Chituru there are refining furnaces and electrolytic plants. At the Western Mines the Musonoi River was diverted by a dam to allow deposits of ore to be mined. The falls of the Lufira River have been harnessed to supply electricity to Jadotville and other centres.
An enormous deposit of limestone was found at Lubudi, 220 miles from Elisabethville, and cement works were built on the slope of the limestone hill. Eight miles from the works the 86-feet falls of the Kalule River have been harnessed to furnish power for the cement mills. The current is carried from the power house to the works, and in the mill each machine is driven by its own electric motor.
The branch of the cement company which builds surface works for the copper mines, factories and buildings has carried out many important civil engineering contracts, including concrete roads, a 170-feet span bridge over the Lufira River and contracts for the mines in Rhodesia.
MOLTEN COPPER in the moulds at Lubumbashi, near Elisabethville. Copper is refined either by the electrolytic process or in small reverberatory furnaces where oxygen and small quantities of other impurities are removed.
The output of copper in recent years has been restricted by agreement with producers elsewhere, but already some 25,000,000 tons of ore, yielding about 1,500,000 tons of copper, have been mined in the Katanga alone. On the Rhodesian side it is calculated that about 30 per cent of the world’s ore reserves are waiting to be tapped. Progress has depended upon the careful work of geologists, who have in years of investigation gained the knowledge of the ore body and prepared the way for the miner. In some instances they have checked the discoveries made years ago by pioneer prospectors and have taken nothing for granted.
As far back as 1902 a Rhodesian prospector named Collier found the Bwana M’Kubwa (“Big Master”) Mine, and also discovered an open lane in the forest on the site of what are now the Roan Antelope claims.
Later it was proposed to get machinery and stores to the mines by wood-burning traction engines towing wagons. For some twenty years, however, nothing was done. Then the Bwana M’Kubwa Mine was opened, and although this mine was afterwards closed its development reawakened interest in Northern Rhodesian mining.
The Roan Antelope Mine was developed and a township called Luanshya, the headquarters of the mine, was laid out. It is linked with the main line at N’Dola by a branch railway twenty-four miles long.
From a point near N’Dola another branch railway leads to the N’Kana Mine, forty-one miles from N’Dola. The extensive plant at N’Kana is a notable example of the change which the engineer has wrought in Africa.
Development of the mine has been conducted through a vertical central hoisting shaft and a smaller vertical opening for advance work. The central shaft has five compartments and is over 1,000 feet deep. It is lined with reinforced concrete to 900 feet. The smaller shaft, which is over 1,500 feet deep, has three compartments. The crushers and concentrator adjoin the central shaft. The smelter has a 300-feet brick-lined steel stack for reverberatory and converter gases. The smelter consists of the reverberatory and converter plant, with the storage, mixing and conveying system, boiler plant and flue system.
Rhodesian “Big Three”
An earth-filled ramp carries the railway line to the coal storage gantry and receiving bins. The receiving bin for the storage of ore and fluxes is a steel structure.
An electric furnace is used to reduce converter slag rich in cobalt for the production of cobalt-copper-iron alloys. The electrolytic refinery consists of the anode department where refined blister copper produced by the smelter is made into anodes, the tank house where the anodes are converted into cathodes by electro-deposition, and a furnace refinery where the cathodes are cast into commercial shapes.
The electrolytic plant is new. Although the N’Kana blister copper is of the exceptional purity of 99·5 per cent copper, even this is not up to the highest grade required for certain work, and therefore the electrolytic refinery was erected. The coal for the mine and the plant is hauled 600 miles from the Wankie Coalfield. A compact town, with European and native hospitals, attractive houses and a hotel, has been built.
The branch line continues from N’Kana to the Chambishi Mine and on to N’Changa, which was the headquarters for the great aerial survey of the copper fields. The Mufulira Mine lies on a railway that connects the N’Dola-N’Chatiga branch with the main line. The Mufnlira, the N’Kana and the Roan Antelope are the “big three” of the Rhodesian mines in recent production.
N’Dola, the railway junction, at one time the last railway station in Northern Rhodesia, grew rapidly with the opening of the mines and became a municipality in 1932, when it became known as the capital of the Rhodesian Copper Belt. Many people believe that the copper country of the Katanga and Northern Rhodesia will one day become the hub of Africa.
The engineer has made it one of the greatest producing regions of the modern world, aisle to supply electrolytic and other grades of copper in accordance with the needs of the future.
THE POWER PLANT at the N’Kana Mine supplies electricity for the refining processes and for the township which has grown up round this copper mine, one of the biggest in Rhodesia. N’Kana is linked by a branch railway to the main line at N’Dola, forty-one miles away.