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There are many methods for preparing flotation reagents. With different preparation methods, the dosage and effect of the same flotation reagents are also very different. Proper preparation before using will play an important role in improving the efficacy of the flotation reagent. Next, we will introduce 9 commonly used flotation reagent preparation methods.
Most water-soluble flotation reagents can be formulated in this way and are typically formulated as 5% to 10% aqueous solutions. Flotation reagents using this preparation method include xanthate, copper sulfate, water glass, and the like.
With this method, the concentration of the flotation reagent solution should not be too low. If the concentration is too low, the volume would be too large. But the concentration should not be too high either. For a flotation reagent with a small dosage, if the concentration is too large, it would be difficult to properly control the dosage of it, and the transportation would be inconvenient too.
When preparing an aqueous solution, we often dissolve the flotation reagent in the container with a small amount of water. After the dissolution, we can gradually add more water to reach the desired concentration.
At the production field, in order to prepare the solution more conveniently, we can engrave a scale with a marked volume on the dispensing tank. Then we can add a known amount of flotation reagent therein and add water till it reaches the scale mark. After stirring the flotation reagent to mix and completely soluble, we can use it.
For some flotation agents that are insoluble or poorly soluble in water, they can be dissolved in a special solvent and added.
For example, dianilinodithiophosphoric acid is insoluble in water, but it can be dissolved in alkaline solution of sodium hydroxide. Therefore, when using dianilinodithiophosphoric acid, it is necessary to prepare an alkaline solution of sodium hydroxide, and then add dianilinodithiophosphoric acid to the alkaline solution to make it become dianilinodithiophosphoric acid solution and then add it to the flotation machine. In addition, dissolving the oleic acid in kerosene and add it into the flotation machine can enhance its dispersion in the ore pulp.
For some non-soluble solid flotation reagents, it can be formulated into an emulsion. For example, the solubility of lime in water is very small. We can grind the lime into a powder, and add water to make it into a milky suspension (such as Calcium hydroxide). Or it can be directly added to the ball mill as dry powder.
For fatty acid collectors, saponification is the most common method. For example, during the flotation of hematite, paraffin soap oxidated and tall oil are often used as collectors. In order to improve the water solubility of the mixed flotation reagent, when preparing the flotation agent, we can add about 10% of sodium carbonate to saponify the tall oil and heat the mixture with hot water to prepare a hot soap liquid.
Another example is the water solubility of oleic acid is very poor, but after adding sodium carbonate to produce sodium oleate, the water solubility becomes better and it is more convenient to apply in the flotation process.
After emulsification, the degree of dispersion of the fatty acid collector and diesel in the pulp will be enhanced, thereby improving its effect.
Emulsification is usually carried out by means of ultrasonic waves, steaming or mechanical agitation. If a part of the emulsifier is added, the emulsification effect will be better. Many kinds of surfactant can be used as emulsifiers. For example, tail oil and diesel oil can be emulsified by adding an emulsifier alkyl aryl sulfonate in water.
For cationic collector (amines), we usually use acidification method. Since the cationic collector is poor in water solubility, it must be pretreated with hydrochloric acid or acetic acid to form ammonium salt, so it can be dissolved in water and used in flotation process.
Some flotation reagents (such as pine oil, dithiophosphate 25, kerosene, etc.) have very low water solubility, and it is difficult to formulate a true solution or a stable emulsion. Instead of formulating it into a solution, it can be directly added into the ore pulp according to the dosage.
The electrochemical treatment of the flotation reagent is to let in a direct current into the solution to electrochemically act on the flotation reagent. This method can change the state of the flotation reagent itself, the pH value of the solution, and the redox potential value, thereby increasing the concentration of the most active flotation agent ingredient, increasing the critical concentration of forming colloidal particles, and improving the degree of dispersion of the insoluble flotation reagent in water.
The aerosol method is a new preparation method that enhances the effect of flotation reagents. The essence of this method is to use a special spray device to directly add the flotation reagent to the flotation cell after the flotation reagent is atomized in the air medium, so this method is also called “aerosol flotation method”. This method can not only improve the floatability of useful minerals, but also significantly reduce the dosage of flotation reagents. With this method, the amount of the collector is only 1/3 to 1/4 of the usual amount, and the amount of the flotation foaming reagent is only 1/5.
In summary, the selection of flotation reagent preparation methods mainly has the following principles:
(1) Flotation reagent that is soluble in water generally using the method of formulating into an aqueous solution. Such as xanthate, copper sulfate, water glass and so on.
(2) For some flotation reagents that are insoluble or poorly soluble in water, they can be dissolved to a special solvent and added into ore pulp. For example, the dianilinodithiophosphoric acid can be dissolved in an alkaline solution of sodium hydroxide, and the oleic acid can be dissolved in kerosene.
(3) For some non-soluble solid flotation reagents, it can be formulated into an emulsion or suspension. For example, lime can be ground and added with water to form a suspension.
(4)For fatty acid collector, the most common methods are emulsification and saponification. If paraffin soap oxidated and tall oil are used together as a collector, they can be treated by saponification. Fatty acid collector and diesel oil can also be emulsified to enhance the degree of dispersion in the ore pulp.
(5)For cationic collectors (amines), acidification is usually used.
(6)Some flotation reagents (such as pine oil, dithiophosphate 25, kerosene, etc.) have very low water solubility and can be added directly to the stock solution.
The above are the nine methods for the preparation of flotation reagents. In practice, it is necessary to select the preparation method suitable for the production situation of the mineral processing plant according to the actual situation and the suggestions of the technicians to achieve the best flotation effect.