Vertimill® is globally recognised as an energy efficient grinding machine. Through a low total cost of ownership, they bring substantial improvement to the profitability of concentrators. During the years, Vertimill® technology has proven to be efficient especially in primary and secondary grinding, regrinding, fine grinding, and lime slaking applications.

Lower capital cost

Fast to install. Less floor space required.

Lower operating cost

Energy efficient. Less frequent maintenance.

Versatile applications

Capable of handling feed sizes up to 6 mm and grinding to products less than 20 microns.

Support from experts

More than 100 years of grinding and minerals processing expertise.

Vertimill® for lower cost and more versatile grinding

Vertimill® is a unique product offered exclusively by Metso. Grind efficiency, reduced media consumption, lower installation cost, minimal maintenance, and minimal liner wear make Vertimill® the lowest total cost of ownership in many applications, substantially improving the profitability of concentrators.

Mechanically, Vertimill® is a simple machine with an agitating screw suspended into the grinding chamber, supported by spherical roller bearings and driven by a fixed speed motor through a planetary gearbox.

The capacity of each unit size is relative to the required power input for the intended grind, however, mills have been operated with throughputs exceeding 500 mtph.

Lower capital cost

Vertimill® requires a simple and small foundation, which means less floor space is required. It is also faster to install than a traditional ball mill, significantly reducing initial costs.

Lower operating cost

Vertimill® is an energy efficient grinding machine. They tend to grind more efficiently than for example ball mills with feeds as coarse as 6 mm to products finer than 20 microns.

Metso has recently developed a 4500 HP (3352kW) Vertimill®, designated the VTM-4500-C. The development of this mill and larger versions makes the practicality of Vertimill® in primary and secondary grinding applications very economical.

Versatile applications

Vertimill® has proven to be a versatile tool that exhibits many advantages over traditional ball milling.

It is capable of handling feed sizes up to 6 mm and grinding to products less than 20 microns, and has standard mill sizes ranging from 15HP (11kW) to 4500HP (3352 kW). 

Support from Metso experts

Metso draws from more than 100 years of mill design and manufacturing expertise, and over three decades of successful Vertimill® applications.

Our engineers will review your specifications and recommend the proper Vertimill® for your application.

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Technical specifications
Someone else might have had your problem before!

How does Stirred Media Detritor (SMD) work?

The feed slurry enters through a feed spout in the top cover which directs the feed into the bottom of the vortex (bottom of the mill) without any inlet head. Grinding media is added either by the automatic Media Addition System through one of the unused feed ports, or manually through the media feed chute.

Final product leaves SMD through the media retention screens, situated around the top of the body and is collected in an external launder and is then pumped, or flows under gravity, to the next stage in the process.

In operating SMD, there is no set combination of parameters, because the different parameters have influence on each other. Experience and practice usually establish optimum operating conditions with the lab testing indicating the initial set points.

The particle size distribution produced is governed primarily by the throughput and the amount of media and multiple mill arrangement. Primary mill control is by media addition to maintain the required power draw to achieve the desired product. Multiple SMDs can be arranged in parallel or series depending on the circuit requirements to affect the particle size distribution.

SMD Operational Control

The effective operation of the SMD requires the following parameters to be accurately and constantly monitored.

Feed Flow-Rate

This parameter is used in conjunction with the feed density and motor power to establish the grinding rate in kWh/mt. Flow rate should be as steady as possible. If the whole stream is feeding direct to the mill, surge tanks should be considered. Feeding SMD from a thickener or scalping cyclone regulates the flow very well and generates a suitable feed density.

Feed Density

The feed density is required, in conjunction with the feed flow-rate, to establish the feed rate of solids. Typical operational feed density range is 30-60% solids. Optimum grinding efficiency is usually in the range of 40-50% solids.

Motor Power/Media Addition

The power drawn by the SMD motor is required to establish the grinding rate. As the grinding media wears fine enough to exit through the mill screens, the total media charge will diminish, and the power draw will decrease.

Media should be added either manually or automatically to maintain as consistent a power draw as possible. SMD is normally operated at 85-100% of full power.

Grinding Media

The grinding media can be varied with a wide range of alternatives, depending on the application and the process requirements. Grinding media plays an important role in grinding efficiency and mill liner wear life so a high-quality media is beneficial, but an economical solution is also important.

How does Vertimill® work?

Vertimill® is typically arranged in closed circuit and fed by the cyclone underflow. The motor power turns the Vertimill® screw at constant speed to stir the grinding balls and slurry.

As the particles are ground, they rise to the top of the mill and overflow into the separating tank. A change in the rotational direction of the slurry when it transitions from the mill to the separating tank causes turbulence which facilitates a settling of the coarser material.

Product from the mill exits the tank through a stand pipe and then to the cyclone sump. The slightly coarser portion of the mill overflow is recycled back into the bottom of the Vertimill®.

The recycle system can reduce cyclone circulating load by allowing the mill to preferentially grind the coarser material. Also, the uprising velocity in the mill can be controlled by a recycle pump to affect the product size distribution, prevent over grinding, and reduce the circulating load from the cyclone.

Final product size is a factor of applied grinding power, flow rate, and slurry density. The effective operation of the Vertimill® requires these parameters to be accurately and constantly monitored and adjusted to meet the required product specifications.

Motor power and media addition

The power drawn by the Vertimill motor is required to establish the grinding rate. Motor power should be measured using corrected power.

As the grinding media wears fine enough to be carried out by the uprising velocity in the mill, the total media charge will diminish, and the power draw will decrease.

Consistent power draw is required to achieve the desired product size, so media should be added either manually or automatically periodically to maintain as consistent a power draw as possible.

Vertimill® has an excellent turndown ratio and can be operated at lower than installed power with less effect on grind efficiency than for example horizontal ball mills.

Feed Flow-Rate

This parameter is used in conjunction with the feed density and motor power to establish the grinding rate in kWh/mt.

Vertimill®can easily handle a fluctuating flow but it should be monitored and can be varied to achieve required product requirement.

Feed Density

The feed density is required, in conjunction with the feed flow-rate, to establish the feed rate of solids.

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