Automatic Vacuum Conveyor for Salt: Powder Transfer Equipment Connecting the Screening Production Line

• The "Last Kilometre" After Screening
  

On a salt production line, after the screening process is completed, the classified salt faces one final challenge: how to transport these finished salt particles from the screening workshop to the packing line or downstream processing steps – cleanly, efficiently and continuously?

This seemingly simple conveying step is in reality full of problems. Manual dumping raises clouds of dust, often shrouding the packing workshop in a "salt mist". The material can easily absorb moisture or break during transport, affecting final product quality. Traditional conveying methods are inefficient and cannot keep up with the production pace.

Is there a conveying method that lets the finished salt "move by itself" – cleanly, without breaking and without absorbing moisture?

The Gaofu automatic vacuum conveyor for salt is designed precisely to solve these problems. Driven by vacuum suction, it uses a fully enclosed pipeline system to automatically transport screened finished salt to packing machines, storage hoppers or downstream equipment, achieving a clean connection from screening to packing.

• Vacuum Conveying: How Salt "Moves by Itself"

The technical principle of vacuum conveying can be summarised in one sentence: using air pressure difference to make material "move by suction" inside a closed pipe.

A vacuum pump continuously removes air, creating a negative pressure state inside the conveying system, lower than the outside atmosphere. Under the action of external atmospheric pressure, salt particles – together with a small amount of air – are drawn into the suction nozzle and travel through the sealed pipeline to the vacuum hopper. Inside the hopper, the salt separates from the air via a filter and falls to the bottom, while the air is exhausted. When the accumulated salt in the hopper reaches a preset level, the discharge valve opens automatically and the salt falls by gravity into a packing machine or downstream equipment. The entire process is controlled by a PLC. After discharge, the system automatically begins the next suction cycle, achieving continuous automatic operation.

Compared with manual handling or mechanical conveying, vacuum conveying offers fundamental differences:

No manual dumping – operators no longer need to carry and pour bags of finished salt; they simply start the machine from a control panel;

Fully enclosed operation – the salt never contacts the outside environment during conveying;

Gentle material handling – vacuum suction is much softer than mechanical methods such as screw conveyors, reducing impact on salt crystals.

For salt, which flows well and has a moderate bulk density, vacuum conveying is naturally a good fit.

• Why Does Salt Conveying Need "Automatic + Vacuum"?

1. Dust Problem: Saying Goodbye to the "Salt Mist Workshop"

In traditional manual dumping, workers carry bags of screened finished salt to the packing machine and pour them into the hopper. Every pour throws a large amount of fine salt dust into the air.

This not only wastes material – the dust that drifts away represents a direct economic loss. More importantly, according to national standards such as GB 2721-2015 "National Food Safety Standard – Table Salt" and the "Measures for the Supervision and Administration of Salt Quality and Safety", the entire process from production to transportation of table salt must comply with food safety requirements. Dust that settles on equipment surfaces or finished product packaging creates a cross‑contamination risk that does not meet food‑grade production environment standards.

The vacuum conveyor uses a fully enclosed pipeline. Salt is drawn directly from the discharge port of the screening equipment into the pipe, never exposed to the workshop atmosphere. The dust problem is solved at its source.

2. Material Protection: Vacuum Suction Is Gentler

Salt is a brittle crystalline material sensitive to impact during conveying. Mechanical methods such as screw conveyors tend to break salt particles, generating more fines and affecting product quality and particle uniformity after packing.

Vacuum conveying uses suction‑driven pneumatic transport. The material is suspended in the pipeline and collides with the pipe walls much less violently than in mechanical conveying, providing better protection for the salt crystals. For table salt, where particle integrity matters, vacuum conveying is the gentler choice.

3. Efficiency: No More "Waiting for People" on the Line

Manual carrying and dumping speeds are limited by the workers' physical strength and skill. It is hard to match the continuous pace of modern screening and packing lines.

The vacuum conveyor operates fully automatically. From suction to discharge, no manual intervention is required. For example, the Gaofu GFZK series vacuum conveyor offers a capacity range from 200 kg/h to 6,000 kg/h, allowing flexible selection according to production needs. Once started, the salt begins to flow automatically – the line no longer stops because it is "waiting for people".

4. Corrosion & Moisture Protection: Special Requirements for Salt

Salt imposes two special demands on conveying equipment: one is chloride corrosion, the other is moisture absorption and caking. Ordinary carbon steel equipment, after prolonged contact with salt, will rust and may even contaminate the product with rust particles – an unacceptable quality risk for table salt production.

The Gaofu automatic vacuum conveyor for salt fully considers these characteristics. All material‑contact parts are made of 304 food‑grade stainless steel – corrosion‑resistant, non‑rusting, eliminating the risk of product contamination. The sealed structure effectively prevents outside moisture from entering the pipeline, avoiding moisture absorption by the salt during transport. For salt dust environments that require explosion protection, Gaofu also offers explosion‑proof vacuum conveyor models to meet more stringent safety requirements.

• Core Technical Advantages of the Gaofu Automatic Vacuum Conveyor

1. Seamless Integration with the Screening Line

The Gaofu vacuum conveyor is designed to work closely with screening equipment.

In a typical integrated screening‑conveying application, the vacuum conveyor works with a vibrating screen (rotary vibrating screen, linear screen or tumbler screen). After the vibrating screen completes particle size classification, the vacuum conveyor uses suction to draw the on‑spec undersize product directly from the screen‘s discharge port into the enclosed pipeline, then delivers it to the packing line or downstream equipment. The screening equipment is placed at the front end of the conveying system, becoming part of an automated feeding process.

This synergy allows the vacuum conveyor to form a closed‑loop production flow together with screening, mixing and packing equipment, achieving fully automated material handling.

2. Automatic Continuous Operation

The Gaofu vacuum conveyor is equipped with an automatic level control device that continuously monitors the material level in downstream equipment (such as a packing machine hopper):

When the material level exceeds the set point, the conveyor automatically stops feeding;

When the material level falls below the set point, the conveyor automatically resumes feeding.

The whole process requires no manual intervention and can run 24 hours a day. One machine can replace the manual handling and dumping work of 3‑5 workers, significantly reducing labour costs while avoiding the inconsistent feeding that can occur with manual operation.

3. Fully Enclosed Dust‑Free Conveying

The Gaofu vacuum conveyor features a fully sealed structure, food‑grade seals and quick‑release clamp connections. The entire conveying process takes place inside sealed pipes and hoppers – no dust escapes. For production lines with even higher sealing requirements, an S‑type flanged design between the hopper sections further prevents any dust leakage.

Another important benefit of the fully enclosed structure is the prevention of foreign matter contamination. For the food industry, this directly supports food safety compliance.

4. Easy to Clean and Maintain

When switching between different batches or types of salt, the conveying equipment must be thoroughly cleaned to avoid cross‑contamination.

The Gaofu vacuum conveyor has a modular, building‑block design. The hoppers are connected with quick‑release clamps, allowing rapid disassembly and easy cleaning. There are no gaps or dead corners where material can accumulate, and the surfaces are easy to inspect visually. Cleaning results can be verified, meeting the hygiene requirements of food GMP standards.

5. Flexible Layout

A major advantage of vacuum conveying is flexible pipeline routing. The Gaofu conveyor can achieve horizontal conveying distances of several tens of metres and vertical lifts of up to 15 metres. The pipe route can be adapted to the actual workshop layout, without being constrained by floor space. Whether in a new plant or a retrofit of an existing facility, installation can be carried out with minimal work.

• Food‑Grade Design: Safeguarding Salt Safety

For table salt producers, the conveying equipment that directly contacts the material must meet food safety requirements.

The Gaofu automatic vacuum conveyor for salt provides systematic food‑grade safety:

Material safety – All material‑contact parts are made of 304 food‑grade stainless steel, compliant with GMP standards. Surfaces are finely polished, with no burrs or dead corners to trap residue;

Filtration system – The conveyor is equipped with a polyester membrane filter or a 316L stainless steel sintered mesh filter, effectively capturing fine salt particles to ensure clean exhaust air and prevent dust emission;

Seals – Food‑grade silicone seals are used – non‑toxic and odourless, ensuring purity during conveying;

Traceability – The system can be connected to a manufacturing execution system (MES) for digital management and traceability of raw material usage, meeting the increasingly strict quality traceability requirements of food producers.

• Core Components of the Gaofu Vacuum Conveyor

The Gaofu automatic vacuum conveyor for salt consists of the following core components working together:

About Gaofu Machinery

Xinxiang Gaofu Machinery Co., Ltd. was originally founded in the 1980s. After more than 40 years of development, the company has become a "National Specialized and Sophisticated 'Little Giant' Enterprise", a "National Green Factory", a "National High-tech Enterprise", a "National Intellectual Property Advantage Enterprise", and the "President Unit of the Vibration Association". It also hosts the "Henan Provincial Industrial Design Center", the "Henan Provincial Engineering Technology Research Center for Intelligent Online Screening Systems", and the "Xinxiang Municipal Engineering Technology Research Center for Fine Screening". The company has been granted more than 500 invention, utility model and design patents, has received the "Science and Technology Achievement Award" issued by the Ministry of Industry and Information Technology, and has participated in drafting four "National Standards".

Gaofu's product portfolio covers several series and hundreds of varieties, including vibrating screening equipment, conveying equipment, and automated material handling systems. Its main products include one-stop solutions such as automatic feeding systems, powder feeding systems, pneumatic conveying systems, weighing and batching systems, minor ingredient batching systems, water supply systems, oil supply systems, fluid conveying systems, central kitchen powder feeding systems, powder conveying systems, and top-loading feeding systems. The food system production lines mainly include:

Bakery production lines: bread production line, cake production line, shortbread production line, croissant production line, toast production line, pizza production line, biscuit production line, hamburger production line;

Dough product production lines: steamed bun production line, stuffed bun production line, twisted roll production line, sesame paste baked bun production line, steamed dumpling production line, dumpling production line, youtiao (fried dough stick) production line, stuffed pancake production line.

Gaofu products are not only popular in Greater China but are also exported to more than 100 countries and regions, including Russia, Canada, the United States, New Zealand, Japan, Brazil, South Africa, etc. They are widely used in many industries such as food, pharmaceuticals, chemicals, metallurgy, building materials, mining, thermal power, and environmental protection, earning the trust and praise of over 10,000 customers worldwide. The company adheres to its mission: "Enhance material quality and efficiency, meet customer needs", walking side by side with customers for harmonious and win-win cooperation. Today, Gaofu has become an approved supplier to many Fortune 500 companies, including CNPC, Sinopec, Sinochem Group, China Resources Group, Sinopharm Group, COFCO Group, China National Building Material Group, China Aerospace, and Jinchuan Group.