What is a spiral classifier？

The spiral classifier is a device that utilizes the principle of different sedimentation speeds of solid particles in a liquid based on their specific gravity for mechanical classification. It is widely used in closed-circuit processes in conjunction with ball mills to separate and classify ore sand in mining plants. It can also be applied in gravity separation plants for classifying ore sand and fine mud, as well as in metal ore dressing processes for size classification of ore pulp. Additionally, it finds application in de-sliming and dewatering operations during ore washing.

Types: There are four classifiers: high weir single spiral and double spiral, submerged single spiral and double spiral.

• High weir spiral classifier is suitable for coarse particle classification, the maximum size of overflow is generally 0.4~0.15mm;
• Submerged spiral classifier is suitable for fine particle classification, the maximum size of overflow is generally below 0.2mm.

Applications of Spiral Classifier

• Mining Plants: Used in conjunction with ball mills to form a closed-circuit for ore sand separation and classification.
• Gravity Separation: Applied for classifying ore sand and fine mud to enhance mining efficiency.
• Metal Ore Dressing: Used in the ore dressing process for size classification of ore pulp to meet subsequent process requirements.
• Ore Washing Operations: Involved in de-sliming and dewatering processes during ore cleaning.

Advantages Of Spiral Classifier

• The energy consumption of spiral classifier is 50% lower than other classification equipment, and the output is also increased by 50%.
• The water tank has a large slope, which is convenient for forming a closed-circuit ring grinding operation with the ball mill, and forms a self-flow sand return.
• Simple operating process and stable working status, greatly reducing maintenance costs.
• Its spiral structure can ensure a large enough settling area to extend the material suspension time, which is more conducive to the even distribution of materials during the classification process.
• Users can adjust the parameters of the spiral classifier according to their needs, such as spiral speed, inclination and outlet size to achieve different classification requirements.

Principle of Spiral Classifier

The working principle of the spiral classifier is based on the different sedimentation speeds of solid particles in a liquid due to their varying specific gravities. When the ore pulp enters the tank from the side feed inlet, it forms a sedimentation zone at the bottom of the tank. The slowly rotating spiral provides a certain degree of agitation to the pulp. After agitation, the light and fine particles suspend on the surface, forming an overflow that flows over the weir at the end of the water tank into the next mineral processing step. The heavy and coarse particles settle at the bottom of the tank, forming a return sand that is transported by the spiral to the discharge port for removal, thus achieving the desired classification.

Structure of Spiral Classifier

The spiral classifier mainly consists of the following components:

• Transmission Device: Includes an electric motor, reducer, cylindrical gear pair, and bevel gear, responsible for driving the rotation of the spiral.
• Spiral Body: Composed of a hollow shaft, supports, spiral blades, and lining iron, which is the main working part of the classifier.
• Tank: Holds the entire slurry and bears the weight of the machine and all its loads. Constructed by welding steel plates and various steel sections.
• Lifting Mechanism: Used to raise or lower the spiral for maintenance or to adjust the processing level within the tank.
• Lower Bearing (Bushing): Supports the spiral and bears the load during operation.
• Discharge Valve: Located at the bottom of the tank, allowing the slurry to be drained when necessary.

General Specification

Model	Spiral  Diameter (mm)	Trough  Length (mm)	Spiral  rotate  speed (r/min)	Processing  capacity（t/d）		Motor  Power （kw）		Dimensions （mm≤）			Total  weight （t）
				Sand -return	Overflow	For  driving	For  lifting	Length	Width	Height
FG-3	300	3000	12-30	80-150	20	1.1	—-	3850	490	1140	0.7
FG-5	500	4500	8-12.5	135-210	32	1.1	—-	5430	680	1480	1.9
FG-7	750	5500	6-10	340-570	65	3	—-	6720	980	1820	3.1
FG-10	1000	6500	5-8	675-1080	110	5.5	—-	7590	1240	2380	4.9
FC-10		8400		675-1080	85	7.5	—-	9600	1240	2680	6.2
FG-12	1200	6500	4-6	1170-1870	155	7.5	2.2	8180	1570	3110	8.5
FC-12		8400		1170-1870	120	7.5	2.2	10370	1540	3920	11.0
2FG-12		6500		2340-3740	310	15	4.4	8230	2790	3110	15.8
2FC-12		8400		2340-3740	240	15	4.4	10370	2790	3920	17.6
FG-15	1500	8300	4-6	1830-2740	235	7.5	2.2	10410	1880	4080	12.5
FC-15		10500		1830-2740	185	7.5	2.2	12670	1820	4890	16.8
2FG-15		8300		2280-5480	470	15	4.4	10410	3390	4080	22.1
2FC-15		10500		2280-5480	370	15	4.4	12670	3370	4890	30.7
FG-20	2000	8400	3.6-5.5	3290-5940	400	11-15	3	10790	2530	4490	20.5
FC-20		12900		3210-5940	320	11-15	3	15610	2530	5340	28.5
2FG-20		8400		7780-11880	800	22-30	6	11000	4600	4490	35.5
2FC-20		12900		7780-11880	640	22-30	6	15760	4600	5640	48.7
FG-24	2400	9130	3.67	6800	580	15	3	11650	2910	4970	26.8
FC-24		14130		6800	490	18.5	4	16580	2930	7190	41.0
2FG-24		9130		13600	1160	30	6	12710	5430	5690	45.8
2FC-24		14130		13700	910	37	8	17710	5430	8000	67.9
2FG-30	3000	12500	3.2	23300	1785	40	8	16020	6640	6350	73.0
2FC-30		14300		23300	1410	—-	—-	17091	—-	8680	84.8