The purification of the aluminium ingot casting technology
Views: 1 Author: Site Editor Publish Time: 2016-10-20 Origin: Site
From all kinds of impurity is contained in liquid aluminum electrolyzer suck out, so the casting needs to be cleaned before.Industry mainly adopts clarification, flux and gas purification method, also some trial directional solidification purification and filtering methods.
1. Flux flux purification is used to join flux form a large number of small droplets of liquid aluminum, the aluminum oxide by these droplets of liquid moisture adsorption and dissolution, the formation of new liquid drop rises to the surface, form scum removal after cooling.Purification with flux choose low melting point, low density, surface tension and large activity, have a very strong adsorption capacity on oxidizing slag composition of salt.When using, the first small flux into the cage, then insert the hybrid furnace bottom agitation, back and forth to take it out of the flux change their cages, rest 5 ~ 10 min. Remove scum on the surface of casting.Also can according to need to flux covering on the surface.
2. Gas purification gas purification is one of the main aluminium purification method, the gas is used in chlorine, chlorine nitrogen or nitrogen gas mixture.
(1) the chlorine gas purification.Before using active chlorine gas purifying agent (chlorination).In chlorination, chlorine gas flux into the aluminum liquid generated within the many abnormal small AlCl3, bubbles, fully mixing in liquid aluminum.Dissolved hydrogen in aluminum liquid, and some mechanical adsorption on AlCl3 bubbles, inclusions and discharge with AlCl3 bubbles rise to the surface of a liquid aluminum.Ventilation with chlorine can also make some more electronegative than aluminum chloride, elements such as calcium, sodium, magnesium has been generated by chlorine gas is piped in corresponding chloride, to separate.So the chlorination process is a very effective aluminium purification method.Chlorine dosage for every 500-700 tons of aluminum g. but because oxygen toxic and is more valuable, in order to avoid the air pollution and reduce the cost of producing aluminum ingots, so in the modern aluminum industry has gradually removed the chlorination process into inert gas, nitrogen gas purification method.
(2) the nitrogen purification method.Is also called smokeless continuous purification method, using alumina ball (418 mm) as filter medium.N2 directly into the liquid aluminum.Furnace to liquid aluminum into continuously, the alumina ball filter layer, and flushing by nitrogen, and non-metallic inclusions in aluminum liquid and to remove dissolved hydrogen, continuous discharge, and then making slight nitrogen foam evenly distributed in the play the role of purification in the treatment of liquid aluminum.Nitrogen gas of atmospheric pollution, and purification capacity is big, can handle 200 ~ 200 kg per minute liquid aluminum, aluminum loss caused by the relative decrease in the process of purification, is now widely used.But it is not like chlorine can remove liquid aluminum calcium, sodium, magnesium.
(3) the mixed gas purification method.A mixture of chlorine gas and nitrogen gas is used to purify liquid aluminum, its effect is on the one hand, remove oxide and hydrogen separation, on the other hand eliminate some metal impurities in the aluminum (e.g., magnesium), the composition of the commonly used 90% nitrogen + 10% chlorine.There are 10% chlorine + 10% co2 + 80% nitrogen.This effect is better, carbon dioxide chlorine and nitrogen good diffusion, can shorten the operation time.
Above is about the purification of aluminium ingot casting technology is introduced, hope can help to you.