Patent AU-2021100249-A4 (AU)
Title: Preparation of Aluminium Electrolytic Anode Coating by Utilizing Waste Aluminium Dross
Inventor: HE YONGDONG
IPC: C25C3/08
Filed: 2021-01-15
Granted: 2021-04-22
Abstract: The invention discloses a preparation of aluminium electrolytic anode coating using 
waste aluminium dross. The formula component includes hydrated lime, calcium 
aluminate, dry matter from electrolysis-dehydration of aluminium dross aqueous solution 
(a mixture of sodium aluminate and potassium metaaluminate), alumina, sodium 
tripolyphosphate and other components. Specifically, the mass percentage of each 
component is 5%-15% hydrated lime + 10%-2 5 % calcium aluminate + 15%-7 0% dry 
matter + 1%- 3 % sodium tripolyphosphate + industrial alumina.  
The preparation of aluminium electrolytic anode coating from aluminium dross is divided 
into two stages. The first stage is the preparation of aluminium dross and the second stage 
is the batching treatment of anode anti-oxidation coating.  
The first stage specifically includes the following steps. Weigh aluminium dross and 
composition analysis. Aluminium dross is dissolved in water and hydrolysed, and direct 
current is applied to the salt solution, so that NaCl and KCl in the salt are electrolyzed to 
prepare NaOH and KOH. The nanometer NaOH and KOH can directly dissolve the 
precipitated aluminium and alumina at the bottom of the electrolyser. After removing iron 
and silicon from the solution, press filtration treatment is carried out. The main 
components of the filter residue are iron oxide and calcium orthosilicate, which are sent 
to the storage yard; the filtrate is sodium aluminate and potassium metaaluminate. The 
sodium aluminate filtrate is evaporated to obtain the dry matter of the mixture of sodium 
aluminate and potassium metaaluminate, which is then as a raw material for preparing 
aluminium electrolytic anode coating.
The second stage includes the following steps. Weighing hydrated lime, calcium 
aluminate, dry matter mixture of sodium aluminate and potassium metaaluminate, sodium 
tripolyphosphate, and industrial alumina according to the requirements of the formula 
ratio. The mixture is mixed and ball-milled to 100-500 meshes. After passing the 
inspection, it is packaged and stored as the finished product of anodized anti-oxidation 
coating.  
The invention uses aluminium dross to prepare aluminium electrolytic anode coating and 
realizes the purpose of recycling the waste and environmentally polluting aluminium 
dross. The aluminium electrolytic anode coating prepared by the aluminium dross of the 
present invention is automatically sintered into a firm protective shell under the 
conditions of the electrolysis process, and the oxidation effect of oxygen in the 
atmosphere on the high-temperature carbon anode is blocked. As the anode is consumed, 
the coating shell components gradually dissolve in the electrolyte, and the main 
components are converted into calcium fluoride, sodium fluoride, and alumina, which are 
raw materials and fluoride salt additives required for electrolytic production. The anode 
coating also has the advantages of reducing anode carbon oxidation consumption, 
prolonging the life cycle of anode carbon blocks, reducing the amount of raw materials 
used for electrolytic production of alumina, calcium fluoride, sodium fluoride and the 
like, and achieving the effect of reducing production costs.
-1/1
Weigh aluminium dross and composition analysis 
Watersoluble and hydrolysis 
Direct currentelectrolysis 
The first stage 
Removing ron and silicon from the solution treatment faste 
aluminium dross 
Sending iro sa fd silio 
press filtration treatment ding ronslag storage yard 
The filtrate is dehydrated by distillation 
Dry matter, mixture of sodium aluminate and potassium 
metaaluminate 
6-------------------------------------------
Weighing materials based on the hydratedlime, sodium tripolyplphate 
reurements of the formula ratio ad alumina 
M ix, ball-mil linlg and sieving I The second stage 
1M--- batching of anode 
anti-oxidation coating 
Aluminium electrolytic anode anti-oxidation coating 
Package and storage 
L------------------------------------------------------------ J 
Fig. 1 
The process flow of preparing aluminium electrolytic anode anti-oxidation coating with 
waste aluminium dross.