National Slag Limited

Lafarge Canada Inc.

David T Horvat

Peter A MacKenzie

Kenneth W Spencer

Metallurgical slag is expanded to produce a lightweight solid by forming a stream of molten liquid slag of controlled rate of flow and mixing the stream of slag with a controlled quantity of water and flowing the interacting mixture of slag and water into a receptacle. The interaction between slag and water is allowed to proceed for a predetermined period of time to form an expanded solid without the addition of any additional cooling water which would otherwise quench the material and vitrify it. In the receptacle, a vaned rotor operates to segment the interacting mixture of slag and water and project the segmented mixture through the air for collection into a heap.

Process and apparatus for making expanded slag

The invention provides a new enclosure for slag pelletizers, and a new method of operating such an enclosure, that minimizes the noise and the escape into the ambient atmosphere of hydrogen sulfide and airborne particulate material produced by the pelletization. The enclosure consists of impereable walls and a roof, the pelletized material being removed through an openable door at one end that is closed during the process. The enclosure has three successive zones, in the first of which contains the pelletizer, this being supplied with only the amount of water needed for pelletization. In the second zone containing the slag pile a plurality of very fine mist producing nozzles supply water to the gases to cool them using its latent heat of evaporation, the amount of water supplied being such as to cool them as much as possible while being limited so that it all remains vaporized and cannot enter the slag pile to increase its moisture content. In the third zone the quantity of water supplied is sufficient to condense the water vapor, entraining the soluble hydrogen sulfide and the particulate matter. The condensed water and entrained material is removed and treated, preferably with waste alkaline water, to stabilize the hydrogen sulfide, remove the particulate material, and recycle the water. The non-condensible gases exiting from the top of the third zone can pass through a chimney to the atmosphere or to a gas scrubber for further scrubbing.

Enclosures for slag pelletization apparatus and method of operation

An enclosure for slag pelletizers, and a method of operating such an enclosure, that minimizes the escape into the ambient atmosphere of airborne fibres produced by the pelletization process, while permitting the necessary free passage of the steam and gases that are also produced. The enclosure roof consists of at least one layer of wire mesh and a system of overlapping baffles is provided beneath the roof at least above the pelletizer to intercept the particulate material, so that the pellets do not disrupt a blanket of the fibre which is allowed to accumulate on the wire mesh to facilitate removal of the remainder of the fibre from the air stream. The method allows the deposition of an effective blanket, while preventing the deposition of too much fibre, so that the gas stream is diverted and flows out of the open end of the enclosure. A first plurality of water-mist producing nozzles is disposed between the mesh roof and the baffles, while a second plurality is disposed above the mesh roof both delivering a fine mist of water to wet fine particulate, causing it to deposit. A plurality of water-jet producing nozzles are disposed above the roof and delivers jets of water to wash the deposited particulate from the roof and baffle system down into the enclosure interior as and when required.

Growing community of inventors

Hamilton, Canada

David T Horvat