Beneficiation Equipment

High-Weir Spiral Classifier

CAPACITY

30–23300 t/d

Application areas：Closed-circuit classification with ball mills, coarse-particle classification, ore washing, desliming and partial dewatering in mineral-processing plants.

Applicable materials：Wet slurries containing gold, copper, iron, lead-zinc, tungsten, molybdenum, phosphate, quartz, feldspar and other mineral ores requiring coarse classification, sand return, washing or desliming.

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Introduction
Advantages
Working principle
Parameters

Product Overview

The XINGAONAI FLG Series High-Weir Spiral Classifier is designed for coarse-particle classification in wet mineral-processing circuits. It is commonly installed with a ball mill to separate the mill discharge into a fine overflow product and a coarse sand-return stream.

Inside the inclined settling tank, coarser and denser particles settle to the bottom and are conveyed upward by the rotating spiral. Fine particles remain suspended and leave the classifier through the overflow weir for downstream flotation, magnetic separation, gravity separation or leaching.

The series includes single-spiral and double-spiral models with spiral diameters from 300 to 3,000 mm. Model selection depends on feed particle-size distribution, slurry solids concentration, mineral density, required overflow size, sand-return capacity and available installation space.

This page covers the high-weir type, which is generally selected for relatively coarse classification and first-stage closed-circuit grinding. For finer classification duties, a submerged classifier or hydrocyclone may be more suitable.

Key Advantages

Stable Classification in Closed Grinding Circuits

The classifier continuously separates fine overflow from coarse sand return, helping stabilize the circulating load in a ball mill grinding circuit. Final performance depends on feed rate, solids concentration, particle density and equipment settings.

Single- and Double-Spiral Configurations

Single-spiral models are suitable for lower sand-return duties, while double-spiral models provide greater coarse-material conveying capacity for larger grinding circuits.

Adjustable Operating Conditions

Classification performance can be adjusted during commissioning through feed rate, slurry density, spiral speed, overflow level and tank operating conditions. Sampling is required after adjustment to confirm the actual overflow size.

Classification, Desliming and Partial Dewatering

In addition to closed-circuit grinding, the machine can remove fine slime from coarser mineral particles and provide partial dewatering as the settled material is conveyed above the slurry level.

Maintainable Wear Components

Wear protection can be configured for the spiral blades and trough according to ore abrasiveness. Manual or motorized spiral lifting is available depending on the selected model and configuration.

Working Principle

Mineral slurry enters the settling pool at the lower end of the inclined tank. Coarser and denser particles settle more rapidly to the bottom, while finer particles remain suspended and leave the machine with the overflow water over the weir. The slowly rotating spiral collects the settled coarse material, conveys it upward along the trough and allows part of the water to drain before discharge. In a closed-circuit grinding system, this coarse sand is returned to the ball mill for further grinding. The actual classification cut is affected by feed particle-size distribution, mineral density, slurry solids concentration, feed rate, spiral speed, overflow setting and tank inclination.

Technical Parameters

Model	Spiral speed (r/min)	Return sand volume (t/d)	Overflow handling capacity (t/d)	Spiral diameter (mm)	Spiral length (mm)	Slope of sink	Drive motor model	Power (kw)	Lifting motor model	Power (kw)	Weight (kg)
FLG-300	7.7	30-80	10-30	Φ300	3900	14-18	Y100L1-4	2.2	manual	-	668
FLG-500	8	145-260	21-75	Φ500	4390		Y112M-6	2.2	manual	-	1600
FLG-750	7.8	100-455	31-165	Φ750	5500		Y132S-6	3	manual	-	2716
FLG-1000	6.7	473-1026	85	Φ1000	6556		Y132M2-6	5.5	manual	-	4000
FLG-1200	5,6,7	1145-1600	150	Φ1200	6500		Y132M2-6	5.5	Y90L-4	1.5	7943
FLG-1500	2.5,4,6	1140-2730	235	Φ1500	8265		Y160M-6	7.5	Y100L1-4	2.2	11827
FLG-2000	3.6,5.5	3240-5940	400	Φ2000	8700		Y160L-6/4	11,15	Y100L2-4	3	20814
FLG-2400	3.6	6800	580	Φ2400	9130		Y200L2-6	22	Y112M-4	4	24194
FLG-3000	3.2	11625	890	Φ3000	12500		Y200L-4	30	Y112M-4	4	42188

Model	Spiral speed (r/min)	Return sand volume (t/d)	Overflow handling capacity (t/d)	Spiral diameter (mm)	Spiral length (mm)	Slope of sink	Drive motor model	Power (kw)	Lifting motor model	Power (kw)	Weight (kg)
2FLG-1200	5,6,7	2290-3200	310	Φ1200	6500	14-18	Y132M2-6	5.5*2	Y90L1-4	1.5*2	15840
2FLG-1500	2.5,4,6	2240-5360	460	Φ1500	8230		Y160M-6	7.5*2	Y100L1-4	2.2*2	22903
2FLG-2000	3.6,5.5	6400-10800	750	Φ2000	8400		Y160L-4	15*2	Y100L2-4	3.0*2	34621
2FLG-2400	3.63	13600	1160	Φ2400	9130		Y200L2-6	22*2	Y112M-4	4*2	42460
2FLG-3000	3.2	23300	1785	Φ3000	12500		Y200L-4	30*2	Y112M-4	4*2	73030

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Frequently Asked Questions

A high-weir spiral classifier is mainly used for relatively coarse classification in wet grinding circuits. It separates ball mill discharge into a fine overflow stream and a coarse sand-return stream. It can also be used for ore washing, desliming and partial dewatering.

A high-weir classifier is generally selected for coarser classification duties, while a submerged classifier provides a larger submerged settling area and is commonly used when a finer overflow product is required. Final selection should be based on test data and the required separation size.

A spiral classifier is often suitable for relatively coarse separation, visible sand return and applications requiring mechanical conveying or partial dewatering. A hydrocyclone is more compact and is commonly selected for finer, high-throughput pressure classification. Feed size, slurry density, capacity and target cut size should be evaluated before selection.

Overflow size is affected by feed grading, particle density, slurry solids concentration, feed rate, spiral speed, overflow setting, tank inclination and circulating load. These variables interact, so the classifier should be commissioned through sampling rather than adjusted according to one parameter alone.

Please provide the ore type, particle-size distribution, solids concentration, mineral density, dry solids throughput, required overflow size, expected sand-return volume, upstream mill model and available installation space.

Settled solids should be cleared or the spiral should be lifted before restart. Smaller models may use manual lifting, while larger models can be equipped with motorized lifting. Do not start the machine against a compacted sand bed.