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Direct Blister Flash Smelting

Outotec® Direct Blister Flash Smelting Process is the only proven technology, which produces blister copper directly in one stage. It is recognized for its straightforward process flow, ease of use and excellent environmental performance.

Compared to the conventional copper-smelting route, the Outotec® Direct Blister Flash Smelting Process provides several advantages such as:

  • High recovery of copper and other valuable metals
  • Low investment and operating costs for the smelter and acid plant
  • No converting process required
  • High sulfur recovery, only one continuous high strength SO2 stream to the acid plant
  • Improved in-plant hygiene, compact equipment, no ladle transportation of molten material

This unique process is the most profitable option for sulfidic copper concentrates containing 30% or more copper. Outotec® Direct Blister Flash Smelting is the only industrially proven direct blister technology.

In the Direct Blister process, the copper concentrate is smelted directly in one step to produce blister copper without converting. The dried feed material and oxygen-enriched process air are delivered to the Outotec® Flash Furnace through the concentrate burner providing a rapidly reacting suspension in the reaction shaft. Molten phases are collected in the settler where slag and blister form separate layers. Furnace off-gases are cooled down in a heat recovery boiler, which also collects part of the dust load. The rest of the particulates are captured in an electrostatic precipitator. Normally all dust is recycled back into the furnace.

Depending on selected slag chemistry and oxidation potential, Blister Flash Smelting slag contains 15 - 25% copper. In Direct Blister smelting, the electric Slag Cleaning Furnace is the standard method for slag treatment. If slag reduction is done in one step, the blister obtained contains some iron. Slag cleaning in an electric furnace can also be done in two steps. This is needed, for example, in cases where some valuable metals like cobalt or nickel must be recovered from the slag. Another two-step approach is to use the Slag Concentrator after the first partial reduction step in an electric furnace. The selected slag cleaning concept is mainly dependent on raw material bases. Owing to the special features of concentrates, all the DB Furnace applications differ from each other as do slag cleaning systems.

Sulfur is recovered from high-SO2 off-gases at the acid plant. One main advantage in Blister Flash Smelting is that there is a continuous off-gas flow with constant, SO2 -rich content. Melt transfer using ladles is minimized in anode furnace operations, as separate converting is not needed. Also, the troublesome fugitive emissions from Peirce-Smith converting aisle are omitted.

Outotec provides complete tailored process solutions for customers’ needs. Decades of experience in the supply of Flash Smelting plants have resulted in extensive metallurgical know-how that ensures the most profitable process choice and its optimal performance. Outotec’s life-cycle technology partnership with the customer spans from the early stages of the process solution design all through the supply and commissioning of the entire process chain with integrated process control and holistic service and support concept. Continuous research and development ensure that the customer is provided with the latest advancements in process and equipment solutions.