Prospector made discovery that created Noranda

In the early 1920s, prospector Edmund Horne discovered along the shores of Lake Osisko, in northwestern Quebec, one of the richest lodes of copper and gold in the world.

Over the years, the deposit was to reveal reserves of more than 58 million tonnes of ore. With great foresight, Noranda Mines — predecessor of Noranda Inc. — established a copper smelter to treat the first ore produced in 1927. Located near the mine, the smelter quickly became one of the world’s largest facilities of its kind.

As the 30s dawned, the company opened its doors to other gold and copper ore and concentrate producers by introducing a practice which was to become its long-term calling: custom smelting — the smelting, on a contractual basis, of ore and materials provided by external clients.

Over the years, the company’s dual roles have evolved. By 1976, the Horne mine had yielded its last ore. But the Horne division was ready, having gradually increased its custom smelting capacity for many years (while maintaining its production from the Horne mine) so that, by 1974, more than 85% of the materials it processed came from outside customers. And since the Second World War, the company had been extending its smelting operations beyond ore and concentrates and had begun to treat scrap metal and residues rich in copper and precious-metal content.

Today, while heavily involved in prospecting, Noranda Minerals operates only one mine in the vicinity of its smelter: the Remnor Mine. Inaugurated in 1985, it extends to the twelfth level of the old Horne Mine, a depth of 410 m. The gold- bearing silicate ore produced is the major source of flux for the smelter.

With the exception of the Remnor ore, all materials smelted by the Horne division come from clients scattered across the two hemispheres.

Each year, the Horne division receives some 800,000 tonnes of concentrate and an ever-increasing volume of industrial scrap, transported to the Horne by road and rail, as well as by ship, through the Ports of Montreal and Quebec. To ensure efficient handling of materials, the Horne division operates an 18-km railway system with five locomotives, and has winter thawing sheds capable of handling 122 railcars.

Each car is weighed, sampled and discharged onto a network of 58 conveyors, leading to a 35,000-tonne storage depot and air dome. Samples from each lot are dried and moisture content is determined. The samples are then ground, mixed and divided into four final fractions for analysis.

In an intermediary step, ore from the Remnor mine, along with custom ores, fluxes and slags, is fed through crushing and screening plants and sampled in trains of Vezin samplers with intermediate particle size reduction. Final samples are also sent to the laboratory for analysis. High tech analysis

The Horne division laboratory, staffed by an experienced, highly- qualified team of chemists and analysts, is equipped with some of the most modern production and development equipment, including computer-assisted ICP Plasma and X-Ray.

The integrated nature of the Noranda Group provides the Horne division laboratory with instant access to technological innovations, keeping the smelter lab at the forefront of evolving technology.

In addition, an environmental laboratory, accredited by the American Association of Industrial Hygiene, provides the highest standard of environmental control, including advanced meteorological measurement and forecasting, thus preventing local environmental upsets. Conventional smelting

Approximately 30% of the incoming concentrate feed, discharged and sampled, is routed to the conventional smelter for modified traditional processing. This begins with feeding the concentrates and required Remnor flux directly into a wet-charged, oxygen fuel-fired reverberatory furnace.

During the smelting process, which takes place at a temperature of 1,300 degrees C, iron oxide and silica unite to form an iron silicate slag, while copper and other metals combine with the unoxidized iron and sulphur, producing material known as “matte.” The matte also dissolves the precious metals contained in the feed.

Heavier than slag and containing 32% copper, the matte settles to the bottom of the furnace. The slag is skimmed from the top of the molten matte, which is tapped and transported by cranes in 16-tonne ladles to one of several converters. Continuous Smelting

About 70% of materials received are sent to the Noranda reactor, which constitutes the heart of the continuous smelting process and represents one of the most advanced smelting technologies in the world.

Concentrate, other metal-bearing feeds and flux are introduced into the reactor, a horizontal cylinder measuring 21.3×4.3 m. The reactor temperature is maintained at approximately 1,300 degrees C and oxygen- enriched air is injected through pipes in the side of the vessel, causing the molten and solid charge to mix vigorously. Iron and sulphur in the concentrate and other feeds, along with impurities such as lead, zinc and other, react with oxygen from the air stream to produce iron and other oxides which are fluxed with silica to form molten slag. A strong gas containing sulphur dioxide also develops. The copper settles as a high grade copper sulphide matte beneath the slag.

The matte is tapped into ladles and taken to converters. The slag, still containing some copper, is skimmed and solidified slowly in 32-tonne ladles, then broken and sent to the concentrator, where the copper is recovered as concentrate and sent back to the reactor. This process results in very high energy efficiency and metal recoveries. The Concentrator’s Role

Initially built to treat ore from the Horne mine, the concentrator consists of three separate circuits and has three main functions today; recovering copper and precious metals contained in the slag from the reactor (about 1,500 tonnes a day, yielding 180 tonnes of concentrate), processing ore from the Remnor mine and treating custom ores. Converters

Metal in the form of molten matte from both the reverberatory furnace and the reactor is fed into five Pierce-Smith converters, immense cylindrical furnaces which, at a temperature of 1,200 degrees Celsius, oxidizes the sulphur and most of the iron and remaining base metals in the matte, and recovers 98%-pure copper containing the precious metals treated. Slag from the converters is either returned to the reverberatory furnace or slow- cooled and co-milled with the reactor slag. Anode Furnaces

The impure molten metal produced by the converters is transported to three refining furnaces, with a combined capacity of 990 tonnes, where final oxidation of sulphur and iron takes place and where the oxygen content of the copper is reduced to 0.05%. Finally, the 99%-pure copper is poured into moulds on a revolving casting wheel and quickly solidifies into anodes, each weighing about 290 kg.

Water-cooled, the anodes are loaded into railcars or trucks for shipment to Noranda Minerals’ CCR Division in Montreal-East, where the copper’s purity is raised through electrolysis to 99.9% and the precious metals, gold, silver, platinum and palladium are recovered. Off-Gases

All of the various hot processes produce hot gases containing particulate metal oxides and sulphates, nitrogen and residual oxygen, moisture and various strengths of sulphur oxides. These gases are treated for removal of particulates, some of which are recirculated to the process while others are shipped to Bathurst, N.B., to recover lead, silver, copper and bismuth. A very large acid plant is being built to recover sulphur as sulphuric acid from the strong gases produced in the Noranda reactor.

Over the years, Noranda Minerals Inc., Horne Division hasn’t stopped at acquiring and developing better weighing, sampling and analytical technologies; it has also built into its processes a flexibility unique by world standards.

Since the 1940s, Noranda’s Horne division has treated more from its customers than ore and concentrates. It has also welcomed a variety and increasing volume of residues and scrap metal containing copper or precious metals and numerous minor elements; concentrates, electronic scraps and cables.

The company has carved itself a key niche in the world metallurgical industry by developing its expertise as a refiner of extremely complex materials containing appreciable concentrations of precious metals and “impurities”. The obvious finds are gold, silver and copper but the list goes on: platinum, palladium, selenium, tellerium, nickel, lead and bismuth.

In 1974, with the adoption of the continuous smelting process, the Horne division’s capacity to treat metals other than copper became potentially unlimited.

In addition to some of the more obvious metals treated, the Horne division is able to effectively treat the deleterious elements such as arsenic, antimony, zinc, cadmium and others. This is due mainly to the development of a specialized process technology for controlling the environmental conditions, the quality of the copper anodes delivered to CCR, and the ultimate quality of the refined copper product for the world market.