Pb/Cu/Ni - Recycled materials
Isasmelt

Isasmelt operates in batch mode so flow and SO₂ concentration vary.  Plant equipped with pre-dry tower (78% H₂SO₄).

NOx
Mist Eliminator candle and cold heat exchanger drainings collected and treated in an Outotec NOx treatment system.

Acid Colour
Hydrogen peroxide used to decolour 78% and 93% product acids.

Basically the recycling operations at the Hoboken Works are streamlined along two processes:
The Precious Metals Operations (PMO) focus on fast throughput and maximized yields at optimized cost. They are fully tuned for the efficient refining of an extended range of complex and valuable raw materials, containing precious metals.
The Base Metals Operations (BMO) focus on flexibly processing by-products from the PMO at the lowest possible costs and optimal throughput times.
Both PMO & BMO enhance the basic success factors of our business model: flexibility, reliability and complexity.
Major investments have been recently completed, to develop, install and run new metallurgical operations, completely shifting Hoboken's focus from concentrates to recyclable materials and industrial by-products. In other words, over the past decade a completely renewed plant has been built on site.
Our processes are based on complex lead/copper/nickel metallurgy, using these base metals as collectors for precious metals and other metals, so called "impurities", such as antimony, bismuth, tin, selenium, tellurium and indium. The main advantage of our innovated plant is increased productivity, combined with greater efficiency, which results in maximized metal recovery rates and generating optimum precious metals yields.

The main processing steps of the Base Metals Operations are the lead blast furnace, the lead refinery and the special metals plant.
The lead blast furnace reduces the oxidized lead slag from the smelter together with high lead containing third party raw materials and transforms them into impure lead bullion, nickel speiss, copper matte and depleted slag.
The impure lead bullion, collecting most of the non-precious metals is further treated in the lead refinery. Besides pure lead the process generates special metals residues. These are, together with the main side-streams of the Precious Metals Operations, further refined into pure metals and metals salts in our special metals refinery to produce high quality indium, selenium, tellurium and antimonate. Some intermediates are tolled out to dedicated companies to produce tin and bismuth.
After leaching the nickel out of the nickel speiss and turning it into nickel sulfate, the remaining precious metals residue is treated at the precious metals refinery.
The copper matte is returned to the smelter.
The depleted blast furnace slag is physically calibrated for use in the concrete industry or used as dyke fortification substance

1995 - Strategic decision taken to innovate the processes in order to treat a more diversified feedstock.  The core of this technological quantum leap was the use of submerged lance technology.  The new smelter replaced the following: roasting plant, sinter plant, 1 of 2 sulphuric acid plants, copper blast furnace and 4 Hoboken converters.