science

VSI mill

VSI mill is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand VSI mill rather than just read about it. In short: A VSI mill (vertical shaft impactor mill) is a mill that comminutes particles of material into smaller (finer) particles by throwing them against a hard surface inside the mill (called the wear plate). Any hard or friable materials can be ground with low value of metal waste.

Key takeaways

VSI mill belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect VSI mill to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of VSI mill from memory before moving on to harder problems.

Reference excerpt

A VSI mill (vertical shaft impactor mill) is a mill that comminutes particles of material into smaller (finer) particles by throwing them against a hard surface inside the mill (called the wear plate). Any hard or friable materials can be ground with low value of metal waste. This type of mill is combined with a classifier for fine tuning of a product size.

Operating characteristic Strength of material - up to 200 MPa Mohs hardness - up to 7 Absolute humidity - up to 1% (strong condition) Feed size - up to 40 mm Product size - less than 0.5 mm Capacity - up to 20 t/h Mill uses for hard and friable materials. Wood, most metals and plastics are inoperable. Raw material must be dry. Capacity strongly depends on characteristics of material and a product size.

Grinding principle

A schematic drawing of a VSI mill is shown at Fig. 1. Raw material particles transports via hopper (1) into the accelerator (2). An accelerator (2) rotates with a high speed and particles increase their speed by a centrifugal force. After leaving channels of the accelerator particles impact with a wear plate (3) in the grinding chamber. A high speed impact leads to destruction of particles into pieces of different size. Big particles (greater than 1 mm) fall down to outlet (5) and later they transport to hopper by an elevator. Other particles (less than 1 mm) lift by air stream into a classifier where blades (4) make rotating dust flow. Middle size particles shift to wall by centrifugal force in a big chamber of a classifier and fall down to cone (6) and later they move into an accelerator (2). Small particles move by air stream to outlet (8). Fine tune of a product size is achieved by changing of blade angle.

Accelerator

A schematic drawing of a VSI mill accelerator is shown at Fig. 2. Very high speed of particle motion needs to obtain good grinding but high speed must lead to high metal waste. Really it doesn't happen because in an accelerator particles move along same material in special inwall area (3) which is bounded by accelerator body and hard metal blade (4). Material in such region holds by centrifugal force. Wear plates (2) and cone (1) use also to avoid wear and tear of an accelerator body.

Usage of VSI mills You cannot use VSI mill 'as is'. It requires organized feeding, an air stream, and its cleaning from product (dust). Therefore, a full complete grinding line consists of a feeder, an elevator, a VSI mill with an air classifier, a cyclone, a fan and a bag filter. If the raw material is soggy, some form of drying is necessary before grinding.

Grinding and product properties Implementation of dry grinding process. Ability to adjust finished product size on-line, during the operation. Superior selectivity of minerals liberation in Titan M mill as compared to conventional ball mills (for example, copper ore-dressing with Titan VSI mill yields 17,6% copper concentrate with 82,6% extraction as compared to 14,5% and 76,1% obtained with a ball mill grinding, respectively). Ability to achieve minerals liberation by coarser grinding (for example, 95% liberation of copper-zinc ores is achieved by VSI grinding to minus 0,3 mm, in comparison a similar result can be achieved with a ball mill grinding to minus 0,074 mm). Increase durability of construction materials ground by Titan M as a result of a mechanical activation (for example, the cellular concrete strength increases 1,5 - 2,5 fold, while cement and lime consumption is reduced by 15 - 25% and by 20%, respectively). Increase in physical and chemical activity of cements, phosphorites and other materials. Low energy consumption.

Illustrations

Worked examples

Example 1 — a first encounter with VSI mill

Start with the simplest possible case. Write down what VSI mill claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to VSI mill before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about VSI mill ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of VSI mill

In research: VSI mill appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses VSI mill in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: VSI mill is common in secondary-school and first-year university syllabi. It links to neighbouring topics Grinding mills, so understanding it makes those chapters shorter.
In everyday life: Look for VSI mill outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study VSI mill in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what VSI mill means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain VSI mill out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is VSI mill in simple terms?

Why does VSI mill matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study VSI mill?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on VSI mill.