Phosphate rock is a kind of rock with a high concentration of phosphate, which is the main raw material for the production of phosphoric acid and phosphate fertilizers. The global demand for phosphoric acid is about 45 million tons annually.
It is of great significance to maintain life on earth and is an irreplaceable mineral resource to ensure food security. Without it, we can't survive at all, and even all of us become "phosphorus eaters". So, do you know how phosphate rock is processed?
Eight beneficiation ways of phosphate rock
Commercial phosphorus is made from phosphate rock, which is enriched after mining. There are eight main ways for phosphate beneficiation, which are suitable for different types of rock phosphate, to improve the grade and quality of phosphorite.
Process 1: Crushing and smashing
Principle: Phosphorus minerals and impurity minerals in rock phosphate are often cemented together in varying degrees, reducing the particle size of the ore by crushing to dissociate them.
Applicable type: Primary siliceous rich phosphorite
Process 2: Scrubbing and desliming
Principle: Rock phosphate often adheres to wet ore mud, which is placed in water to remove the surface mud materials and separate fine ore particles, such as phosphate mud, clay ore, and fine quartz. Water washing can also remove certain soluble substances, such as sodium chloride.
Applicable types: Weathered or mud-rich phosphorite
Process 3: Grading
Principle: After crushing and washing, it is often necessary to classify the crushed phosphate minerals, to dissociate and separate the fine-grained embedded phosphate minerals from impurity minerals.
Applicable type: Phosphorite with less clay
Process 4: Flotation
Principle: This is the most commonly used beneficiation way, often adding inhibitors to restrain the flotation of certain minerals, making the separation more effective. Positive flotation is to use flotation agent to float phosphorus minerals according to different chemical properties of the mineral surface, to achieve the purpose of separation; reverse flotation is to make impurities float and phosphate minerals sink.
Applicable types: Siliceous phosphate rock, colloidal phosphate rock, sedimentary calcareous phosphate rock, apatite, endogenous apatite
Process 5: Heavy media sorting
Principle: Based on the different densities of minerals, choose magnetite, ferrosilicon, or a mixture of both as a weighting agent, so that the density between phosphate minerals and carbonate minerals. One mineral floats up in the medium and the other sinks to separate phosphorus minerals.
Applicable type: Carbonate phosphorite
Process 6: Magnetic separation
Principle: According to the different magnetism of minerals, ferromagnetic minerals are separated from non-magnetic minerals under the action of the magnetic field.
Applicable type: Rock phosphate containing magnetic minerals such as iron and titanium
Process 7: Calcination and digestion
Principle: A chemical beneficiation way, it is used to remove organic matter, carbon dioxide, and some fluorine from rock phosphate so that phosphate minerals accumulate.
Applicable type: Sedimentary calcareous phosphorite with high carbonate content
Process 8: Photoelectric separation
Principle: A physical separation way, it identifies different ores according to differences in their physical properties, such as the reflectivity of light, the color of reflected visible light, etc., relying on a certain external force to separate phosphate ore from impurity minerals.
Applicable type: Separation of phosphate minerals from high magnesium vein minerals
Phosphate rock production line - Ftmmachinery successful case
The beneficiation process of rock phosphate depends on the specific situation, using different processes to deal with.For example:
- Phosphate rock in Florida: From the layered sediment deposited on the seabed, the process mainly includes wet screen classification, desliming, and flotation.
- Phosphate rock in Morocco: A sedimentary phosphate rock deposit, using processes such as crushing and grading, water washing, wet screening, desliming, and dehydration.
Ftmmachinery engineers can provide tailor-made processing ways according to the nature of different phosphate ores. Taking the production line of the Middle East phosphate project as an example, this blog will explain to you the beneficiation process and the equipment that can be provided, from the four stages of “crushing - grinding - flotation - dehydration”.
Stage 1: Crushing
The rock is sedimentary calcareous rock phosphate and transported to the raw ore bin and enters the jaw crusher through the vibrating feeder. After coarse crushing, the phosphorite enters the cone crusher again for medium and fine crushing and is screened through the circular vibrating screen. After that, the rock phosphate particles enter the grinding bin.
- Achieving coarse and fine crushing, the discharge particle size reaches 5-50 mm.
- High compressive strength and reliable work.
- Easy maintenance and low construction cost.
- About 70% of the concentrate can be produced before flotation, effectively reducing production costs.
Stage 2: Grinding
The grinding process is a closed-circuit grinding process, which consists of a ball mill and a hydrocyclone to form a closed circuit. The material is fed to the ball mill by an electromagnetic vibrating feeder so that the phosphate minerals are ground into powdes.
Equipped equipment: Electromagnetic vibrating feeder → Ball mill → Hydrocyclone
- The discharge particle size can reach 0.075-0.4 mm.
- The machine runs smoothly, with high intelligence and high wear resistance.
- Good environmental protection.
Stage 3: Flotation
The rock phosphate powders overflow from the cyclone to the flotation machine, adopting the reverse flotation process. After the closed-circuit flotation process, the obtained product with high phosphorus content is phosphorus concentrate, which is pumped into the concentrate thickener. The remaining impurities are tailings, sent to the tailings thickener.
Equipped equipment: Flotation machine
- It has triple functions of suction, slurry suction, and flotation.
- Without auxiliary equipment and higher efficiency.
- Low energy consumption, simple operation, and long service life of wearing parts.
Stage 4: Dehydration
The dehydration process usually includes two processes: concentration and filtration. High-efficiency thickener is used to process the ore powder, and it is filtered and dehydrated by a vacuum filter. The phosphate concentrate is sent to the concentrate yard by a belt conveyor, and the tailings are pumped to the tailings pond.
Equipped equipment: Thickener → Filter
- Dewatering of concentrates and tailings of ore.
- Self-control facilities and large processing capacity.
- Good environmental protection.
Through this technical design, the rock phosphate production line is reasonable, efficient, and productive, effectively reducing costs. The entire beneficiation is environmentally friendly and can be recycled. The company provides the professional customized solution. What's more, I didn't expect to have engineer guidance and even on-site service, which greatly reduced my concerns.
Challenges in phosphate processing
With the development of the times, countries around the world pay more and more attention to protecting environment. Of course, phosphorite will also bring challenges in the processing. However, Ftmmachinery engineers carefully plan the equipment to meet the challenges, which reduces environmental impact.
1. Dust problems
Phosphate beneficiation plants are prone to dust problems. The mined phosphate rock will be dried before and after processing, and it is easy to become dusty. But through closed circuit and loop design, or collecting fines in the bag filter, fine-grained aggregation reduces dust problems.
2. Corrosive solvents
Many corrosive solutions are often added when phosphate rock is processed to produce phosphoric acid. Usually, special alloys and liners are used on equipment to prevent corrosion, extend equipment life, and provide special treatment for solvents.
3. Solid wastes
Solid wastes are produced after phosphate ore processing, such as phosphogypsum and quartz sand. Phosphogypsum is a by-product of the phosphoric acid process, and the water used to transport phosphogypsum can be settled and returned to the plant for recycling. The quartz sand produced in the process of phosphate fertilizer production can be separated, washed, and reused as building materials to reduce waste.
According to different types of phosphorite, it is necessary to adopt flexible and effective beneficiation process. The rock phosphate is widely used, such as phosphoric acid, phosphate fertilizer, food, medicine, matches, dyes, chemicals, and other industries.
Ftmmachinery has produced various equipment for more than 40 years, providing professional beneficiation ways and processing equipment. Whether you are using it for phosphating or fertilizers, we can help you. If you have any needs, please contact us immediately!