ZincOx Resources plc at its Annual General Meeting in June said that over the past few months, both the recovery and reliability of the plant have improved significantly and the feed rate is now being increased while the operating parameters are optimised so as to maintain a high recovery of zinc oxide.
The Korean Recycling Plant (KRP), located in South Korea, treats electric arc furnace dust in a rotary hearth furnace to recover zinc oxide concentrate and iron. While the zinc grade of KRP’s feed material has risen by about 10% over the past year, the grade of the zinc oxide concentrate recovered continues to improve and is currently running at about 64% zinc. The design modifications required in the circuit that produces KRP’s iron by-product, ZHBI, has only recently been completed and commercial test marketing is underway.
However, these improvements have been masked by continuing repairs required by the inner tubes of the heat exchangers. These repairs have been caused by failure of the welds and the resultant ingress of air has accelerated corrosion. The air ingress limits throughput and ultimately results in stoppages for repairs of up to ten days at a time.
These heat exchangers, fabricated in Germany, are to be replaced with ones made in a significantly more resistant alloy. This has to be specially manufactured and so the new tubes will only be installed later in the year. Meanwhile, the offgas flow will be modified so that, as required, one side of the heat exchanger equipment can be isolated and repaired while the other continues to operate. Since these units were designed with excess capacity the plant will still be able to operate at 80-85% of capacity during any periods of isolation and for the remainder of the time the facility is expected to operate at full capacity giving a monthly throughput of over 95%.
The stoppages and reduced throughput caused by the problems with the heat exchangers has severely reduced zinc concentrate production which has been limited to about 45% of target capacity over the past three months. To cover the cost of repairs, the heat exchanger by- pass and the fabrication of new inner tubes, the Company is in the process of finalising a loan for up to US$7M, which will be secured against the Company’s land in Turkey, details of which will be announced in due course”.