Complete difference between vertical mill calcium carbonate and ordinary calcium carbonate (Raymond mill/ring roller mill)
The ordinary calcium carbonate referred to in the industry is mostly heavy calcium produced by traditional Raymond mills and small ring roller mills; Vertical grinding calcium carbonate is a high-end heavy calcium produced by a large-scale vertical roller press grinding integrated production line. There is a significant difference between the two in terms of powder morphology, processing performance, and downstream product effect, especially suitable for making PP/PE filling masterbatch.
Ⅰ、 Difference between production equipment and grinding principle
1. The vertical mill calcium carbonate adopts a vertical grinding disc and hydraulic grinding roller extrusion grinding, with built-in drying and multi-stage wind grading integrated system. The material is compacted in a thin layer, and the grinding roller does not directly contact the grinding disc. It has less dust and built-in water removal function, suitable for large-scale continuous production.
2. Ordinary calcium carbonate (mainly Raymond mill) relies on a shovel to throw the material between the grinding roller and the grinding ring for collision, friction and crushing, without built-in drying, resulting in low grading accuracy; Easy to produce coarse particles and impurities, with fast equipment wear, mostly for small and medium-sized low-end powder production lines.
II、 Core differences in physical indicators of powders
1. Particle shape and particle size distribution (most importantly)
Vertical grinding calcium: extruded into shape, with round and elliptical particles with few edges and corners; Narrow particle size distribution, small span between coarse and fine particles, no large or coarse particles, controllable content of 2 μ m fine powder, and uniform and stable powder.
Ordinary Raymond calcium: shattered by impact, with sharp and needle shaped particles; The particle size distribution is wide, with a large amount of coarse slag and a large difference in thickness, making it easy to produce large particle white spots.
2. Adjustable fineness range
Vertical mill: fully covered with 325-1500 mesh, stable ultra-fine powder, suitable for high-end wire drawing and thin film special calcium powder.
Ordinary Raymond mill: mainstream 325-400 mesh, with a few improved models up to 600 mesh, making it difficult to consistently produce ultrafine powder.
Ⅲ. Moisture, whiteness, and oil absorption value
1. Moisture: The vertical mill comes with drying, and the moisture content is ≤ 0.2%; Ordinary calcium has no drying, and the moisture content is generally above 0.4%. Granulation is prone to foaming and water marks.
2. Whiteness and chromaticity: Low temperature rolling with a vertical mill is not prone to heating and yellowing, and the whiteness is stable and high; Ordinary high-speed friction heating can cause yellowing and significant color difference fluctuations in the powder.
3. Oil absorption value: The rounded particles of the vertical mill have small gaps, resulting in a lower oil absorption value; Under the same mesh size, additional filling can be added without slipping or precipitation, suitable for high filling masterbatch.
4. Liquidity and dispersibility
The flowability of the standing powder is excellent, and the powder is not easy to clump together; Ordinary calcium has many edges and corners, high friction, and is prone to agglomeration. Granulation is prone to crystal points and poor dispersion.
5. Comparison of processing performance when making filling masterbatch
Smooth extrusion granulation of vertical grinding calcium: evenly dispersed, twin-screw extrusion does not block the mesh or accumulate carbon, with few broken bars and high production efficiency; High filling of over 75% is also stable. Ordinary calcium: more coarse particles, frequent clogging of the filter screen, and frequent shutdown for cleaning; High filling is prone to white spots and pockmarks.
6.The appearance of the finished masterbatch is vertical grinding masterbatch: the particles are smooth, the whiteness is high, and there are no mixed colors or black spots; The downstream blown film and injection molding have good surface gloss. Ordinary calcium masterbatch: prone to yellow spots and small black slag, the surface of the product is rough, matte, and has raised particles.
7.Special advantages for wire drawing/thin film: vertical grinding of ultra-fine calcium as film masterbatch: lower haze, better film toughness, and less prone to film breakage; The wire is continuously drawn and the thread is flat and straight. Ordinary calcium film: high haze, rough texture, easy breakage of flat fibers, uneven surface of woven bags.
8.When the mechanical properties of the product are added in the same proportion, the vertical grinding calcium filled product has good rigidity, impact resistance, creep resistance, smaller molding shrinkage, and is less prone to warping and deformation of injection molded parts; After ordinary calcium filling, the toughness decreases significantly and the product tends to be brittle.
Ⅳ、 Cost, Capacity, and Applicable Scenarios
1. Capacity and long-term costs
Vertical mill: A single production line can produce tens of tons per day, saving more than 20% energy. It is suitable for long-term stable supply to large masterbatch factories and has lower comprehensive processing costs.
Ordinary Raymond mill: small single output, high energy consumption, frequent replacement of vulnerable parts, suitable for small low-end building materials and low-end filling.
2. Price positioning
Limestone calcium carbonate belongs to the mid to high end powder category, with a slightly higher unit price than ordinary Raymond calcium; But when making high filling masterbatch, the addition ratio can be increased, and the overall cost of raw materials is actually more cost-effective. Ordinary calcium carbonate is inexpensive and only used for low-end disposable products and low requirement injection molding.
Ⅴ、 Differentiation of downstream application selection
Prioritize the use of vertical grinding calcium carbonate (high-end filling masterbatch)
1. PE blown film masterbatch: for express bags, plastic films, and food packaging films, low haze and high dispersion are required;
2. PP non-woven fabric, flat yarn, and geotextile masterbatch to reduce fiber breakage;
3. High filling injection molding masterbatch: household appliance shells, modified PP for automobiles, turnover boxes;
4. Food grade filling masterbatch, high gloss board, and vacuum formed meal box masterbatch;
5. High filling 70% -80% high content filling masterbatch.
Low end scenarios that can use ordinary calcium carbonate
1. Low end building filling, ordinary cement filling;
2. Low cost disposable plastic flower pots and simple plastic storage;
3. Low requirement woven bags and low-end packing ropes, with no strict requirements for appearance and toughness.
Ⅵ、 Short Summary
1. Vertical grinding calcium: round particle shape, uniform particle size, low moisture content, low oil absorption, good dispersion, smooth granulation, better product gloss and toughness, suitable for high-end films, wire drawing, and high filling masterbatch;
2. Ordinary Raymond calcium: with many edges, uneven thickness, high moisture content, and easy yellowing, it is only suitable for low-cost low-end filling products;
3. Make PP/PE filling masterbatch, pursue high filling, stable production, and good appearance of finished products, and prioritize the use of vertical grinding calcium carbonate.
