Kaolinite Recovery: Dry and Wet Processing Technologies

Kaolinite is a vital industrial mineral whose recovery processes aim to maximise product grade and recovery rates, ensure high brightness standards, and optimise cost-effectiveness in production operations. Currently, two primary processing routes are employed: dry and wet methods. The dry process is simpler but yields lower product quality, while the wet process is more complex yet produces higher value-added products.

I. Dry Recovery Process and Application Fields

The dry process is primarily suited for applications with less stringent requirements for whiteness and purity. Its workflow includes:

Crushing raw materials to the specified particle size;

Feeding the material into a rotary dryer for drying;

Grinding the dried material;

Removing most coarse particles via flotation technology.

Primary Applications: Kaolin processed via the dry method is chiefly utilised in the rubber industry, as well as for manufacturing paper fillers, glass fibre, and sanitary ware.

II. Wet Recovery Process and Core Workflow

The wet process is pivotal for the deep processing and purification of kaolin, finding extensive application in the paper industry where exceptional quality is paramount. Its core lies in progressively separating concentrates of varying particle sizes through multi-stage dispersion, classification, and dewatering. The primary workflow is as follows:

1. Raw Material Preparation and Preliminary Washing

Raw materials are conveyed into hoppers via forklifts or excavators, then transported through feeders and belt conveyors to the sand washer. This equipment disperses, agitates, and preliminarily cleans agglomerated kaolin.

2. Intensive Scouring and Screening

The material subsequently enters a friction-type ore washer, where vigorous friction removes surface-adhering viscous sludge. The cleaned material is screened through a drum screen, where oversize waste rock is discarded. Undersize material proceeds to a twin-spiral sand washer.

3. Multi-stage Spiral Washing and Concentrate Extraction

First-stage spiral sand washer: Overflow constitutes kaolin concentrate, while underflow enters the second stage.

Second-stage spiral sand washer: Overflow again forms concentrate, with underflow directed to a wheel sand washer.

Wheel Sand Washer: Overflow constitutes concentrate, while underflow proceeds to the dewatering screen stage.

4. Dewatering Screening and Waste Separation

First-stage Dewatering Screen: Material passing through constitutes concentrate; oversize material enters the second-stage dewatering screen.

Second-stage Dewatering Screen: Oversize material constitutes coarse waste, discharged via conveyor belt; undersize material constitutes concentrate.