Pneumatic conveyance of bulk materials distinguishes between thin-, mixed- and dense stream conveying.
Advantage of the dense stream conveying is the high material load and therefore a low material speed. This has positive effect on the wear in the conveying line and leads to low maintenance and operational costs.
Velco machines allow the conveyance of diverse bulk materials such as carbon, lime, additives, DRI, but also filter dust.
Injection of carbon dust and lime:
The foaming slag technique had been introduced in the 1980s to improve the productivity of electric arc furnaces. In this case, oxygen and fine carbon are injected into the slag via 1-4 spots. The arising foamed slag insulates the melting bath. The consumption is 10-15 kg C per ton/Fe.
Lime can be blown into the EAF due to metallurgical reasons resp. for protection of the side walls.
Injection of filter dust:
By refeeding of filter dust reduction of the overall dust amount and increase of zinc share in the filter dust.
The analysis correction occurs in the ladle furnace. For this purpose fine carbon, lime or CaSi are injected into the melt while using self-consumable or monolithic lances.
Examples of use:
Automatic addition of EBT filling sand by a pneuamtical conveying installation and receiving bin above the EBT.
- Automatic sand filling without operator work
- Significant reduction of operator hazards in the work area
- optionally with camera to check the quality of sand filling
- Sand amount can be programmed and adapted to shell live, resp. tap hole wear
- Proven low speed pneumatic transport for long lifetime of steel pipes and bend
Injection of Rutilit:
The company Hüttenwerke Krupp Mannesmann GmbH (HKM) in Duisburg-Huckingen/Germany use an injection installation of Messrs. VELCO Gesellschaft für Förder-, Spritz- und Silo-Anlagen mbH, Velbert/Germany at their blast furnace B. The installation has been designed for the injection of fine grained solids as for instance Rutilit and carbon dust which are injected through the blast furnace tuyeres. Rutilit is a synthetic titanium oxide carrier. By the specific injection at selected tuyeres the temperature can be reduced in the blast furnace hearth at local hot spots.
The chosen titanium dioxide carriers do principally consist of titanium dioxide and iron oxide that are coexisting in mineralogical advantageous oxidic phase. The free titanium dioxide will be reduced to titanium in the blast furnace by carbon or silicium. In the liquid iron the metallic titanium together with that in the pig iron soluted carbon and nitrogen form titanium nitrides and titanium carbon nitrides - high temperature resistant compounds that will settle at the inner refractory lining of the blast furnace. There it will result in a rapid growth of a protective layer. This protective layer shall protect the hot spots in the furnace to achieve projected lining points. Hot spots in the furnace will be located by thermal elements being installed around the furnace and then Rutilit sand will be injected via the above positioned tuyeres during the slag tap time. The injection process will be stopped when a "normal" temperature has been achieved. If Rutilit is not required, the installation can be used for the injection of carbon fines as cost-saving substitution of heavy fuel. About 4500 t of carbon has been injected in total from October 2008 - März 2009.
The installation consists of a storage silo with a volume of 90 m³ that will be filled by silo trucks. The injection dispenser has two outlets that are connected with the lance in the tuyere by a conveying line of 70 m. The injection capacity is approx. 40 kg/min. per line.
• Einblasen von Filterstaub in den Kupolofen zur Reduzierung des Staubanfalls
• Einblasen von Feinkohle als preisgünstige Alternative zum Satzkoks
• Einblasen von feinkörnigem FeSi zur schnellen und preisgünstigen Analysenkorrektur im Kupolofen
- Injection of filter dust. By refeeding of filter dust reduction of the overall dust amount and increase of zinc share in the filter dust.