9 Considerations When Buying a Vibrating Screen

How much do you know about vibrating screen? How to choose suitable vibrating screen for mineral processing plant? This article will give you nine suggestions when purchasing vibrating screen. Lets's dive in now!

Screening is the process of separating the crushed materials strictly according to the particle size. The main purposes of the screening operation are as follows:

• Preventing the fine-grained particles from entering the crushing equipment to increase their production capacity and work efficiency.

• Preventing the coarse-grained particles from being selected for the next operation, and ensure that the particle size of the crushed or grinding products meet the requirements.

• Providing feed ore with a narrow particle size range for some gravity operations to improve the separation quality.

• Further improving the quality of the products obtained in the separation process, and ensure that the quality of the final products of the concentrator meet the requirements.

According to the purpose of screening, it can be divided into five types:

• Auxiliary screening. Mainly used in the crushing operation of the beneficiation plant.

• Independent screening. Its purpose is to obtain the final product suitable for the user's requirements, generally divided into pre-screening and inspection screening. Pre-screening refers to the screening operation before the ore enters the crusher. Inspection screening refers to the screening after crushing. Its purpose is to ensure that the final crushed products meets the particle size requirements of the grinding operation and return the unqualified crushed products to the crushing operation.

• Preparation screening. Its purpose is to prepare for the next operation, such as the gravity separation plant to screen and classify the materials before jigging so that to classify particle size as coarse, medium and fine products.

• Dewatering screening. Its purpose is to remove the moisture of the material, which is generally common in coal washing plants.

• Selective screening. If the distribution of useful components in the material is very different in each particle size, you can screen and classify to obtain different quality particle sizes, and screen out the low-quality particle size, thereby correspondingly improving the quality of the material.

The factors affecting the screening process can be divided into the following three categories:

• The physical properties of the materials that enter the screen, including the particle size composition, humidity, mud content and shape of the ore particles. Other factors other than humidity cannot be changed at will.

• Movement characteristics and structural parameters of the screen surface, including movement characteristics, the length and width of screen surface, the size and shape of the screen holes, the effective screen surface area, etc.

• Operating conditions, including productivity and feed ore evenly.

Screening efficiency refers to the ratio of the actual mass of the product under the screen to the mass of the material contained in the screen that is smaller than the screen size.

• Use large-size screen. The large circular vibrating screen increases the vibration force and amplitude, and also reduces the blockage of the screen surface, so that the material to be screened can be loosened, stratified and screened quickly.

• Increase the screening area. When the actual amount of material on the screen surface is about 80% of the screen capacity, the screening efficiency is the highest.

• Adopt a reasonable angle of inclination. The inclination angle affects the flow rate of the material on the screen surface. Generally, the moving speed of the material on the screen surface is controlled below 0.6m/s, and the screen surface maintains an inclination angle of about 15° to obtain a higher screening efficiency.

• Adopt equal-thickness screening. The use of polyline screen surface with different inclination angles controls the different movement speed of the material in each section of the screen surface, so that the ore flow forward, thereby increasing the chance of the difficult-to-screen particles at the discharge end.

• Adopt multi-layer screen with enlarged screen holes. Adopt multi-layer screens with gradually increasing screen holes and decreasing screen surface inclination angles from the lower layer to the upper layer, that is, screen surfaces with different inclination angles and screen holes are used for different particle sizes to prevent block the screen holes and improve the screening efficiency. 

Practice has proved that different shape of the screen surface has different effective screen surface area and different chance for particles to pass through the mesh. The effective area of the rectangular mesh is the largest, followed by the square, and circular mesh is the smallest. The shape of the screen mesh best to match the shape of the material. Block materials should use square mesh, and plate materials should use rectangular mesh.

According to its structure and movement characteristics, it can be divided into the following types: 

• Fixed screen. 

• Cylindrical screen. 

• Plane shaking screen. 

• Vibrating screen. 

• Probability screen.

• Fine screen.

Compared with other screens, the vibrating screen has the following advantages:

• Higher productivity and screening efficiency. Due to the strong movement of the screen surface, the speed of the material passing through the screen holes is accelerated.

• Wide range of applications. It can be used for the screening of fine particles, medium coarse particles and coarse particles, and can also be used in dewatering and desliming operations.

• Favorable screen passing performance. When screening sticky and moist ores, the screen holes are not easy to be blocked.

• Simple structure and convenient operation.

• Low energy consumption.

• Unable to start or small amplitude. The main reasons are: motor damage or circuit components failure; too much material on the screen surface; Vibrator is malfunctioning; insufficient voltage.

• Abnormal material flow. The main reasons are: the horizontal level of the screen is not aligned properly; the stiffness of the support spring is too large or damaged; the screen surface is damaged; the feed is extremely unbalanced.

• Poor screening quality. The main reasons are: the screen hole is blocked; the moisture of the material increases, the material layer on the screen is too thick; the screen is not pulled tightly, and the transmission belt is too loose.

• Breakdown of vibration exciter bearing. The main reasons are: low matching degree between the vibration exciter bearing model and the exciter; insufficient space for thermal expansion of the bearing; poor lubrication of the bearing or the impact of external dust.

Screening equipment is one of the most important automation equipment in the concentrator, and the normal production of the concentrator needs a good operation of the screening equipment. Therefore, it is very important for concentrator to choose reasonable screening equipments.

Through Mining Pedia you can learn about different screening equipment types and scope of application. It is recommended to purchase professional equipment from a qualified manufacturer, which can help you improve the efficiency of mineral processing and maximize your benefits.