Treatment of Ore

Mount Morgan Gold Mine 1888

When the "syndicate" was formed in 1882 by the three Morgan brothers, Frederick, Thomas, and Edwin (Ned), together with three Rockhampton business men, William Knox D'Arcy (solicitor), Thomas Skarratt Hall (bank manager), and William Pattison (grazier), to treat the oxidised auriferous (gold-bearing) ore from the mountain top, it was thought that the gold could be recovered by amalgamation in the usual manner. Late in 1882 a ten head stamp battery was erected on the north bank or mineside of the Dee River where it makes a sharp bend just opposite where Meyenberg Gully joins the Dee. Shortly afterwards a fifteen head battery was erected about four hundred yards downstream from the first battery. However, it was discovered that the very fine, tarnished looking gold was not amenable to amalgamation, up to 75% of the gold being lost in the tailings. When the loss became known, the tailings were stored for future treatment but already many tons had gone down the Dee River.

The syndicate tried many other gold saving devices, such as Berdan Pans, Wheeler Pans, Arrastra Pans and others without success.

Legend has it that some samples taken from the mountain top went as high as 2000 ozs per ton, but this would be an exception rather than the rule.

The Morgan brothers eventually sold their shares in the syndicate to the remaining members of the syndicate, apparently having no faith in the life of the mine.

During the life of the syndicate, sales and transfers of interests had so complicated matters that in 1886 they decided to form a properly formed, registered company with a nominal capital of one million one-pound shares.

The batteries operated until the formation of The Mount Morgan Gold Mining Company, Limited in 1886.

The Mount Morgan Gold Mining Company, Limited (now referred to as the "Old Company"):

On the 1st of October, 1886, The Mount Morgan Gold Mining Company Limited was registered in the Supreme Court of Queensland, with a nominal capital of one million one-pound shares.

The Shareholders were Thomas Skarratt Hall (158,332 shares), William Knox D'Arcy (358,334 shares), William Pattison (125,000 shares), Walter Russell Hall (125,000 shares), John Ferguson (116,667 shares), Charles Carlton Skarratt (58,334 shares) and Alexander William Robertson and John Wagner (together) (58,333 shares).

As amalgamation was unsuccessful for the recovery of the fine gold, a better method was sought and it was subsequently found the chlorination process was the most suitable method, claims being made to a 95% recovery of the gold. Chlorination consists of dissolving the gold with chlorine gas and precipitating the gold from solution with charcoal.


In 1886 the company completed the erection of a chlorination plant known as the Lower Works, not far from the original battery site and on what became known as the Lower Yards. In this method, the ore was finely ground, roasted to remove organic matter and traces of sulphides and then mixed in revolving wooden barrels with chloride of lime and sulphuric acid to dissolve the gold. Interaction between chloride of lime and sulphuric acid generates chlorine gas. The contents of the barrels were then discharged into open vats, the gold-bearing solution drained off and passed through beds of charcoal to precipitate the gold. The charcoal was burnt off and the gold melted and poured into ingots.

Originally the ore was carted to the plant by horse and cart but in 1888 an aerial tramway was built from the mine to the lower yards, which considerably lowered transport costs. The Lower Works was in operation until 1907.


The Lower Works plant was so successful that a similar type of chlorination plant, known as the Upper Works, was built on a site now occupied by the Smelter. It was completed in 1888 and treated 1000 tons of ore per week (the Lower Works treated 500-800 tons per week). The Upper Works ceased operations in 1901.
In 1892, Captain G.A. Richard, who was chlorinator at the Lower Works, devised a method of leaching the ore with a solution of chlorine gas dissolved in water in open vats instead of revolving barrels. The chlorine gas, generated in stone stills by the reaction between sodium chloride (salt), manganese dioxide and sulphuric acid, was passed up through absorption towers and the resultant chlorine liquor added to the material in the open leaching vats. This new method gave just as satisfactory results as the barrel method and was more simple and economical.


Following the discovery of open vat leaching, a new chlorination plant, known as the West Works, was erected on the side of the mountain above Mundic Creek, well to the west of the western boundary of the company's freehold (hence its name). The first section was completed in 1896. This plant was designed to treat 2000 tons per week, but with the installation of gas producers in 1904 for better roasting, the tonnage was increased to 2500 tons per week. Most of the ore for the West Works came from shallow opencut operations above the 285 feet mine level. The West Works closed down in 1910.

At this time, attention was being directed to the treatment of auriferous pyritic ore that was found below the top oxidised zone. Various types of roasting furnaces were tried in the Upper Works, the most satisfactory furnace being a local type called the Hall-Richard Furnace, which consisted of a shaft furnace set on top of a hand-rabbled reverberatory furnace.


With successful roasting of the pyritic ore, a new chlorination plant, the Mundic Works, was built in 1899, on the site where the present No.1 concentrating mill now stands. The Mundic Works operated until 1912, and had a capacity of 2000 tons per week. The leaching vats were considerably larger than those of the older West Works but the principal difference was the use of the Hall-Richard type furnace. As time went on, the copper content of the ore going to the Mundic Works was increasing, and as copper also dissolved in the chlorine solution, the liquor was passed through launders containing scrap iron to precipitate the copper. The Mundic Works ceased operation in 1912.


In 1902, development work on the lower levels of the mine disclosed the existence of high-grade copper ore and in 1903, a diamond drilling programme proved that an extensive body of high-grade copper ore did exist. It was apparent that a different type of treatment was called for, and the diamond drilling campaign proved that there was sufficient high-grade copper ore to warrant the erection of a "smelter."

In 1904, a small experimental blast furnace was built and as the ore proved to be amenable to this type of treatment it was decided to build a smelter.

Richard Shepherd, an expert in copper smelting and fresh from supervising the Chillago smelters, was engaged to supervise the erection of the smelter (blast furnace) at Mount Morgan, on the site originally occupied by the Upper Works.

Three rectangular, water-jacketed blast furnaces were built, the first being blown in on January 20, 1906, the second three months later and the third two years later. A fourth blast furnace was eventually erected, with the fifth being built in 1911.

The furnaces treated high-grade copper ore from the mine. Fluxes such as lime and iron oxide were a necessary part of the smelting process. Lime came from Marmor and iron oxide (haematite and magnetite) from Iron Island, 100 miles north of Keppel Bay. Later pyritic ore (iron sulphide) containing up to 2% copper was used in place of the iron oxide. The furnaces produced two products Ñ a copper matte (copper iron sulphide) and a worthless slag which went to the slag dump. The gold and silver were contained in the matte. The matte went to the "converters" where it was converted into metallic copper (blister copper), the gold and silver reporting in the blister copper.

In 1912, because the metal content of the ore was decreasing and also because of increasing costs and problems in smelting, it was decided to concentrate the copper-bearing minerals (together with the gold and silver) and smelt the concentrates. This entailed extensive rebuilding.

In 1912, Benjamin Magnus, General Manager of the Electrolytic Refining and Smelting Company, Port Kembla, was brought to Mount Morgan to replace Captain Richard as General Manager and to supervise the new programme. It is written that Magnus was a tough man for a tough situation.

In 1913, a "concentration plant" was established and three new blast furnaces were completed in 1914. The concentration mill was built using the shell of the old Mundic Works. The crushed ore delivered to the mill was ground and then passed through jigs and over Wilfrey vibrating tables to separate the heavier gold-bearing material from the remainder of the ore. The tailings from the vibrating tables were re-ground and passed to the flotation section (mineral separation flotation cells Ñ usually referred to as M.S. cells) to concentrate the copper minerals. The tailings from the flotation section went to the tailing dams. At the end of 1916, the concentration mill was treating up to 600 tons per day. The concentrates from the vibrating tables and flotation section were sintered and smelted. Because of the strong up-draft of air in a blast furnace, fine material, such as concentrates, had to be sintered (agglomerated) before smelting to prevent excessive loss through dusting, hence the need of a "sintering plant."

Magnus brought Adam A. Boyd to Mount Morgan as Superintendent of Mines, the latter becoming General Manager in 1915 when Magnus returned to America.

Operations were successful until after the end of World War I (1918), when the price of copper began to fall, mining costs began to rise, and the company began having industrial and financial problems. A scheme to lower mining costs by open-cut mining was considered but was abandoned after an unfavourable report by an eminent American mining engineer, Mr. E.E. Barker. However, the mine struggled on until 1925 when serious industrial strife closed the mine. The men went on an indefinite strike, the underground workings which were heavily timbered were gutted by fire and in an effort to control the fire, the mine was flooded with water. This was the "end of the road" for the Mount Morgan Gold Mining Company, Limited, and it went into voluntary liquidation in 1927.


The next chapter of the history of the Mount Morgan mine is dominated by the courage and faith of Adam Alexander Boyd. As General Manager of the Mount Morgan Gold Mining Company, Limited (now referred to as the Old Company), he had not agreed with the American expert's report that it would be unprofitable to mine the Mount Morgan ore body by open-cut methods. Accordingly, he set about trying to interest others in the formation of a new company to buy and operate the mine.

In July, 1929, a new company, Mount Morgan Limited, was floated with a nominal capital of 200,000 pounds, of which only 95,000 pounds was paid up and most of this was required for the purchase of the mine.
In the early stages, the new company derived its income by pumping copper water out of the mine and recovering the copper by precipitating it on scrap iron in launders, returning water over the surface of the then existing shallow open-cut to dissolve more copper as it percolated down to the lower levels. However, with falling copper prices and lack of finance the new company was facing a difficult time.
Hope lay in working the mine by open-cut methods and revitalizing the existing concentration plant. Advances in concentration techniques (froth flotation) had vastly increased the concentration ratio (now 22:1), making much lower grade ore now profitable.

In 1931, independent laboratory tests in Australia confirmed overseas tests that 87% of the copper and at least 75% of the gold could be recovered by froth flotation. Mount Morgan was also fortunate that Mount Isa Mines made their pilot plant available to Mount Morgan's experienced metallurgist, Brian Lennon, and his pilot plant tests confirmed the laboratory tests.

Prospects brightened in 1932 when the Prime Minister, the Right Honourable J.A. Lyons, announced that his government was prepared to assist the metalliferous mining industry and arranged for the State Government to make a loan of 15,000 pounds to Mount Morgan Limited. The loan was repaid in eight months. Timbers used in the underground mine

So in 1932, open cut mining was commenced and the existing concentration mill was remodelled, replacing the previous concentration methods with modern froth flotation cells. This mill became known as No.1 Sulphide Mill. The gold-bearing copper concentrates were dried, bagged and shipped to Tacoma, Washington, U.S.A. for smelting.

In 1939, a "reverberatory furnace" was installed to smelt the concentrates and produce blister copper at Mount Morgan. It was built on the site of the old smelters. The reverberatory furnace produced matte which was converted to blister copper.

As a certain quantity of low grade oxidised ore was still available, an Oxide Mill (cyanide plant) was erected in 1936 to treat this material. After crushing, the ore was ground in a cyanide solution and the pulp agitated to dissolve the gold and silver. The pulp was filtered and the clear solution mixed with zinc dust to precipitate the gold. The precipitate was acid treated, roasted and smelted into high grade bullion, assaying 870 fines gold, 100 fines silver and 3% copper.

When cyanidation ceased in 1944, the mill was converted to treat low grade sulphide ore by froth flotation, and became known as No. 2 Mill. It ceased operations in 1976.

In 1968, Mount Morgan Limited became a subsidiary of Peko Wallsend Limited.

In 1972, a new type of smelter, a flash smelter came into operation, replacing the reverberatory furnace. The flash smelter also produced matte which was converted to blister copper.

In July 1981, production of ore from the mine ceased. Mined for 99 years, Mount Morgan yielded a total of 225,000 kg of gold, 50,000 kg of silver and 360,000 tonnes of copper and Ironstone Mountain became a huge hole in the ground 1066 feet (325 metres) deep from the original mountain top.

No. 1 Mill continued to operate until 1982, treating ore from Mount Chalmers, but closed down when mining at Mount Chalmers also ceased.

The flash smelter continued to operate at full capacity, smelting concentrates from Peko's Warrego Mine near Tennant Creek, N.T. until July 7th, 1984, closing down when these concentrates were no longer available.

A Carbon-in Pulp cyanide plant, costing about 25 million dollars to construct and planned to recover gold and silver from accumulated mill tailings containing a gram of gold per tonne, commenced operations in September 1982 and ceased operations on the 9th November 1990. This plant produced a further 13979.293 kg of gold and 4535.167 kg of silver.

The carbon-in-pulp cyanide plant consists of reclaiming the stored tailings from the tailings dams by dredge, agitating the pulp with cyanide to dissolve the gold and silver, with subsequent agitation of the pulp with activated charcoal to absorb the gold from solution onto the charcoal. The charcoal containing the absorbed gold is separated from the pulp by passing the mixture over screens. The charcoal is desorbed by heating the loaded charcoal at 95 degrees C. in a strong caustic-cyanide solution, the gold and silver passing back into solution. The solution is electrolysed, the gold being deposited on steel wool. The steel wool plus precipitate is smelted with suitable fluxes to produce a gold-silver bullion. The carbon is re-activated by heating and used over again.