Method and device for regeneration of stainless steel mixed acid pickling waste acid by spray roasting process

Abstract

The invention relates to a method and device for regeneration of stainless steel mixed acid pickling waste acid by a spray roasting process. The method comprises that waste acid is oxidized at a high temperature by a roasting furnace so that solid iron powder and acidic gas are produced, and the products are subjected to spraying absorption so that mixed acids are produced. The device comprises the roasting furnace, a raking machine, a pelletizer, a venturi scrubber, an absorption tower and a washing device. The top of the roasting furnace is provided with two spray guns, the spray guns can be lifted by a pneumatic device, the bottom of the roasting furnace is connected to the raking machine, the raking machine is connected to the pelletizer by a rotary valve, the roasting furnace is connected to the venturi scrubber, the venturi scrubber is connected to the absorption tower, the absorption tower is connected to the washing device, and the washing device is connected to a denitrification system by a smoke exhaust fan and a transverse liquid drop separator. Waste acid is roasted and decomposed at a high temperature to produce iron oxide powder and recovered acid, stainless steel metal ions and free acid capable of chemical combination with acid in pickling are recovered, and the recovered acid is returned to a pickling line for recycle so that acid consumption is reduced.

Description

technical field [0001] The invention belongs to the field of stainless steel mixed acid pickling waste acid regeneration in the metallurgical industry, and in particular designs a method and device for regenerating stainless steel mixed acid pickling waste acid by using a spray roasting method. Background technique [0002] Stainless steel must undergo pickling process before cold rolling. The pickling solution is usually prepared by mixing nitric acid and hydrofluoric acid. The waste acid produced after pickling is generally treated by neutralization method in small and medium-sized enterprises, although some parameters can be adjusted to discharge standards. , but the free acid and metal oxides in the waste acid cannot be recovered, which is a waste of resources. The use of quicklime to neutralize the sludge will cause a large amount of sludge, and some harmful elements will also be discharged, causing serious pollution to the environment. In small and medium-sized enterpri...

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Problems solved by technology

[0002] Stainless steel must undergo pickling process before cold rolling. The pickling solution is usually prepared by mixing nitric acid and hydrofluoric acid. The waste acid produced after pickling is generally treated by neutralization method in small and medium-sized enterprises, although some parameters can be adjusted to discharge standards. , but the free acid and metal oxides in the waste acid cannot be recovered, which is a waste of resources. The use of quicklime to neutralize the sludge will cause a large amount of sludge, and some harmful elements will also be discharged, causing serious pollution to the environment. In small and medium-sized enterprises, The law of neutralization is still in use today

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