Introduction

The Company develops industrial plants that process zinc bearing industrial wastes using its proprietary “Full Cycle” technology to treat zinc bearing waste dusts generated by the steel industry. The Full Cycle process transforms the various components of the dust into valuable products which leaves no solid waste. As such it represents a a major breakthrough both economically and environmentally.

Feedstock

Steel is generally protected from corrosion by galvanising, a process whereby a thin coating of zinc is applied to the surface of the steel. This coating insulates the steel from reaction with air oxidation, rusting) and so prevents corrosion. Steel, and therefore scrap, is becoming increasingly galvanised. Scrap iron and steel is mostly recycled in electric arc furnaces (EAF) where the volatile constituents (Zn, Pb, Cl, Na etc) are driven off as fine particles, together with fine particles of rust. In order to prevent these particles from entering the environment these solids are filtered out of the EAF’s offgas by filtration. The Electric Arc Furnace Dust or EAFD recovered in these filters has a typical composition as follows:

Since zinc is a relatively volatile element it constitutes between about 18% and 31% of the EAFD. When the scrap is added into the furnace any small amount of moisture on the surface of the scrap immediately and explosively evaporates, taking with it rust on the surface of the scrap, this rust is iron oxide which constitutes 20% to 35% of the EAFD, and the final major component is oxygen as the zinc and iron occur mainly as simple oxides. Another major component is iron.

In addition, the EAFD contains lead, cadmium and arsenic, all toxic elements which are, to some extent, soluble in water. EAFD has, therefore, generally been regarded as a hazardous waste. There are estimated to be 7 million tonnes of EAFD generated annually from over 1,000 EAFs globally, probably making EAFD the world’s largest inorganic hazardous waste product.

Existing Practice

The steel mills need to dispose of the EAFD either in landfill or to processors which recover the zinc. At long term zinc prices, treatment plants based on existing technology have not been developed unless a significant disposal fee has been paid by the steel mills. These plant rely on zinc revenue alone and other elements create a substantial tonnage of waste.

ZincOx Technology

The core process technology was built in Korea and is based on the rotary hearth furnace which splits the dust into two intermediate products, a zinc rich fume that is filtered out of the offgas and an iron rich solid product.

Since first production in Korea in 2012, the exceptional quality of these intermediate products has been consistently demonstrated. In 2013 the company began to investigate ways of taking advantage of their quality by creating value added products.

Laboratory testwork and piloting has demonstreated that both these products can be upgraded to produce added value final products and various by-products, so that nothing goes to waste.

The iron intermediate product can be upgraded in a Submerged Arc Furnace (“SAF”) for the recovery of pig iron and a slag of a composition that allows its use in cement works. The zinc intermediate product or concentrate can be upgraded in a Consecutive Metal Leaching (“CML”) plant which recovers an industrial quality zinc oxide chemical (IZO). ZincOx refers to the integrated facility comprising the RHF and upgrading equipment as the “Full Cycle<” technology.

The first plant ZincOx designed to use Full Cycle technology is under construction in Vietnam, by Korea Zinc. The plant is designed to treat 100,000 tpa of EAFD for the production of about 30,000 tpa of zinc oxide.