O que você sabe sobre o classificador espiral para equipamentos de classificação?

Classificador em espiral

O classificador em espiral is primarily used in mineral processing to separate materials based on particle size by utilizing a rotating spiral screw within an inclined trough, where larger particles settle to the bottom and are carried upwards by the spiral, while finer particles overflow with the water at the lower end; essentially, it classifies materials based on their settling velocity in a water slurry, with coarser particles being separated from finer ones.

Vantagens do classificador espiral

• A areia devolvida é automaticamente elevada a uma certa altura e depois diretamente devolvida à extremidade de alimentação do moinho de bolaseliminando a necessidade de um alimentador combinado e economizando muito o investimento em equipamentos e construção civil;
• A continuidade e estabilidade do retorno de areia e a alta concentração de retorno de areia são conducentes ao aumento da concentração de minério de moagem, melhorando assim a eficiência de moagem;
• O tamanho de classificação pode ser controlado de acordo com as diferentes quantidades de alimentação e concentrações de transbordo;
• Estrutura simples, operação e gestão convenientes, operação fiável e baixo custo de manutenção.

Tipos de classificadores espirais

(1) According to the overflow weir height

According to the overflow weir height, that is, the position of the spiral in the flume is different from the height of the slurry surface, the spiral classifier can be divided into three types: tipo de açude alto, tipo de açude baixo e tipo de afundamento. 

• Classificador espiral de alta resistência
  The overflow weir of a high-weir spiral classifier is generally positioned above the lower bearing center of the spiral shaft and below the upper edge of the spiral at the overflow end. Compared with a low-weir design, the high-weir classifier provides a larger settling area. The overflow weir height can also be adjusted within a certain range, allowing the effective settling area to be modified according to classification requirements. High-weir spiral classifiers are generally suitable for relatively coarse classification. They are often used in the first stage of grinding, particularly when the required separation size is relatively coarse.
• Lclassificador espiral ow weir
  The overflow weir of a low-weir spiral classifier is generally lower than the center of the overflow-end bearing. Consequently, its effective settling area is relatively small, and its overflow capacity is limited. The strong agitation generated by the spiral can also disturb the slurry surface. Therefore, low-weir spiral classifiers are generally not the preferred option for fine grinding classification. They are more commonly used for coarse ore washing, desliming, or dewatering applications involving relatively low mud content, depending on the specific process requirements.
• Sclassificador espiral submerso
  In a submerged spiral classifier, several turns of the spiral blades at the overflow end are completely submerged below the slurry surface. This creates a relatively large and deep settling area. Because the classification zone is deeper and the slurry surface is relatively stable, submerged spiral classifiers are suitable for finer classification.

Due to the difference in structure between the high weir type and submerged spiral classifier, the two play different roles in grading operations. The high weir spiral classifier is more suitable for separating coarse grains with a particle size larger than 0.15mm, often used in the first stage of milling; while the submerged spiral classifier is more suitable for separating overflow products with a particle size smaller than 0.15mm due to its smooth grading surface, high overflow yield, and fine particle size, often used in the second stage of milling to form a joint unit with the mill.

(2) According to the number of spiral shafts

De acordo com o número de eixos espirais, o classificador espiral pode ser dividido em espiral simples e espiral dupla. The grading performance of the two is the same, but the double spiral classifier in the sand processing capacity, overflow processing capacity, and the same specification spiral diameter are significantly larger than the single spiral classifier. The price of the double spiral classifier is much higher than that of the single spiral classifier. So it is more suitable for large-scale milling machines with the use.

Mineral processing experts suggest that the single spiral classifier should be used as much as possible under the determined processing capacity. According to statistics, the spiral working load of the double spiral classifier is 0.6-0.75 times that of the single spiral classifier, and the efficiency is relatively low. Therefore, when choosing the spiral classifier, it is necessary to determine its appropriate spiral speed and number according to the processing capacity.

Conclusão

Spiral classifiers remain an important type of classification equipment in mineral processing plants. Although hydrocyclones have become increasingly common because of their compact footprint and strong fine-classification capability, spiral classifiers continue to offer advantages in grinding circuits that require stable coarse-particle return, simple operation, and reliable mechanical classification.

High-weir, low-weir, and submerged spiral classifiers have different structural characteristics and applications. Likewise, single-spiral and double-spiral models differ mainly in processing capacity and equipment investment.

Therefore, there is no universally optimal classification equipment for every fábrica de processamento de minerais. The best choice depends on ore properties, target particle size, processing capacity, grinding circuit configuration, slurry conditions, plant layout, and economic considerations.

For mineral processing plants, the key is to understand the working principle and application characteristics of each classification equipment type and then select the most appropriate solution according to actual production requirements. Proper classification can reduce unnecessary overgrinding, improve grinding efficiency, stabilize the beneficiation feed, and ultimately contribute to better overall plant performance.