PAC is a flocculant of new concept, the specific properties of which derive from the action of its basic active constituent, namely Poly Aluminium Chloride.
This is a polynuclear complex of polymerised hydro-aluminium ions, with the following general formula: { Al2 (OH)n Cl 6-n }x
PAC is supplied in form of water solution or as powder, which facilitates the transport and storage operations and subsequent dosage of the reagent.
The PAC 18% production process lines in the batch etching reaction of alumina with an acqueous solution of hydrochloric acid.
The reaction takes place in a glass-lined reactor equipped with internal agitator. During reaction the reactor temperature is controlled and at end of reaction the reaction product is discharged into an holding tank.
The discharged product is maintained in agitation and non reacted alumina and insolubles are separated by filtration.
The clarified product is transferred into vessels where the product is taken to standard specification. To this scope water, hydrochloric acid, aluminium sulphate can be mixed into the product according to market specifications.
A venting system assures the collection of vent discharges for storage tanks and safety valves.
The liquid effluents, mainly acid waters, are collected into a holding tank from which they are recycled to the production plant.
| Technical Name | Poly Aluminium Chloride |
|---|---|
| Chemical Formula | Aln(OH)mCl 3 nm |
| Formation | Poly Aluminium Chloride (Liquid) |
| CAS Registry No. | 1327-41-9 |
| HSN | 2827 |
| Specifications | PAC 18% | Alum 8% | PAC 9HB | |
|---|---|---|---|---|
| Appearance | clear liquid | Liquid | clear liquid | |
| Density at 20°C | kg/dm 3 | 1.35 | 1.20 | |
| Viscosity at 20°C | Cst | 21.6 | 10-20 | |
| Freezing point | °C | -20 | ||
| pH at 20°C | N. | 0.8 - 0.12 | 2 - 3 | |
| Al 2 O 3 content | % | 18 | 8 | 9 |
| Al 2 O 3 /Cl ratio | max | 3.3 - 3.5 |
| Characteristics | Units | PAC 18% Liquid | PAC 14% Liquid | PAC 10% Liquid Medium Basicity | PAC 10% High Basicity |
| Appearance | Yellow | Pale Yellow | Light Yellow | Pale Yellow | |
| Density
at 20 0 C |
(gm/cc) | 1.35-1.41 | 1.300-1.360 | 1.190-1.210 | 1.200-1.220 |
| Al 2 O 3 | % wt | 16.5–18.0 | 13.5–14.5 | 9.5–10.5 | 10.2–10.5 |
| Chlorides
as ‘Cl’ |
% wt | 20–23 | 15–20 | 11–13 | 10.0–10.5 |
| Basicity | % | 35–45 | 25–35 | 40–50 | 64–80 |
| P h of 5% Solution | 3.0–4.0 | 3.0–4.5 | 3.4–4.5 | 3.5–4.5 | |
| Sulphate as SO 4 | % wt | 1.5–2.2 | 1.2–1.8 | 0.8–1.5 | 0.8–1.5 |