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Flotation: Stirring, Concentration, Mass Fraction of Pulp

Published time:04 April 2023

Ore slurry is a liquid mixture formed by adding solid raw materials such as ore and ore soil to water and other auxiliary materials to extract target elements in industrial production.

In the flotation process, there is a certain relationship between pulp and flotation. Next, we will talk about the stirring effect of pulp, the relationship and influence of pulp concentration and flotation, and the influence of pulp mass fraction on flotation.

What is the role of the stirring of the pulp?

The agitation of ore pulp can promote the suspension of ore particles and even dispersion in the tank; it can promote the good dispersion of air and make it evenly distributed in the tank; it can promote the dissolution of air in the high-pressure area of the tank, and strengthen the precipitation in the low-pressure area, to create a large number of active microbubbles.

Strengthening aeration and agitation is beneficial to flotation, but it should not be overdone because excessive aeration and agitation will cause the following disadvantages:

  • Promote the merger of bubbles;
  • Reduced concentrate quality;
  • Increased power consumption;
  • Increased the wear and tear of various parts of the flotation machine;
  • The volume of slurry in the tank decreases (this is because the part occupied by air bubbles increases the volume of the tank);
  • Excessive stirring may also cause the mineral particles attached to the air bubbles to fall off.

The most suitable aeration volume and stirring degree in production should determine through experiments according to the type and structural characteristics of the flotation machine.

 

What is the influence of pulp concentration on the flotation index?

The pulp concentration can affect the following technical and economic indicators:

  • Affect the recovery rate. When the pulp concentration is small, the recovery rate is low. As the pulp concentration increases, the recovery rate will also increase, but the recovery rate will decrease if it exceeds the limit. The main reason is that the concentration is too high, which destroys the aeration condition of the flotation machine.
  • Affect the quality of concentrate. The general rule is that the quality of the concentrate is higher when flotation in a thinner slurry, and the quality of the concentrate will decrease when flotation is in a thicker slurry.
  • Affect drug consumption. When the ore pulp is thicker, the dosage per ton of ore is less, and when the concentration of the pulp is thinner, the dosage per ton of ore is increased.
  • Affect the production capacity of the flotation machine. As the pulp concentration increases, the production capacity of the flotation machine calculated by the processing capacity also increases.
  • Affect water and electricity consumption. The thicker the pulp, the smaller the water and electricity consumption per ton of ore.
  • Affect the flotation time. When the flotation pulp is thicker, the flotation time increases slightly.

In short, when the pulp concentration is thicker, it is beneficial to the flotation process. But if it is too large, the pulp and air bubbles cannot flow freely, and the aeration effect will deteriorate, reducing the quality and recovery rate. Therefore, the department of flotation of various ores should determine the appropriate slurry concentration according to the properties of ores and related technical requirements.

 

pulp and flotation

 

 

What is the relationship between pulp concentration, flotation conditions, and ore properties?

Determining the most suitable pulp concentration during flotation is related to ore properties and flotation conditions. The general rule is:

  • Thicker pulp is used for minerals with large specific gravity, and thinner pulp is used for minerals with small specific gravity;
  • Thicker pulp is used for the flotation of coarse-grained materials, and thinner pulp is used for the flotation of fine-grained and muddy materials.
  • Thicker pulp is used for roughing and sweeping, which can reduce the consumption of reagents and the number of flotation machines. In comparison, the thinner pulp is used for beneficiation, which can obtain high-quality qualified concentrate.

The slurry concentration is 25%-35% for roughing ore, 10%-20% for flotation fine-grained and high-mud ore, 10%-20% for beneficiation, and 20%-30% for sweeping.

 

What is the influence of pulp mass fraction on flotation?

The pulp mass fraction is an important process factor of flotation and has a very important influence on flotation. There are generally two ways to express the mass fraction of the pulp:

  1. The Liquid-solid ratio is the ratio of liquid to solid mass (or volume) in the pulp. This representation method is very convenient for the calculation of the pulping process.
  2. The percentage of solid content (%) indicates the percentage of solid mass (or volume) in the pulp. This method of expression is widely used in beneficiation experiments and production.

 

The primary influence of pulp mass fraction on flotation has the following aspects:

  • Recovery rate. Within a specific range, when the pulp mass fraction is low, the recovery rate is low; when the pulp mass fraction increases, the recovery rate increases accordingly. However, the mass fraction of the ore pulp should be a manageable size. If it is too large, it will be difficult for the flotation machine to aerate normally in the ore pulp, reducing the recovery rate instead.
  • Concentrate grade. The general rule is that the concentrate rate is higher when flotation is in thinner pulp, and when flotation is in thicker pulp, the concentrate rate is lower.
  • Dosage of medicine. The flotation agent must maintain a certain mass fraction in the pulp to have a good flotation effect. When the ore pulp is thicker, the mass fraction of the chemical agent increases. Accordingly,  the required mass fraction of the chemical agent can achieve with a less chemical agent, and the dosage of the chemical agent per t of ore is correspondingly reduced. Conversely, when the pulp is thinner, the dosage of the agent increases.

 

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