Milling:FCB's comminution adviser assesses the performance of the Horomill in the four years since the original installation
Mar 1, 1998 12:00 PM
Gerard Marchal
  Since the presentation at the 1993 VDZ Congress of the first industrial application of the mill, many units have been installed at plants around the world, and we now have the opportunity to assess its performance in a variety of applications.

The principle has been presented so often that it is not the purpose of this article to put forward another description of the machine other than the briefest outline. Horomill is based on the particle bed compression principle of energy saving in which a shell, supported by slide shoes, rotates at a hypercritical speed. Inside the shell, a hydraulic roller exerts a pressure on the grinding bed, often causing material to become attached to the inner face of the shell by hypercritical shell speed. Scrapers are employed to remove this material, which then falls onto a diverting system, which pushes the material against the shell face for regrinding and adjusts the motion of this material inside the mill. The material is ground several times before leaving the mill and being classified by a high-efficiency TSV classifier.

Tables 1 and 2 show which plants are currently operating the Horomill and the typical results. It is clear that the specific energy is low compared to conventional solutions, with the mill consumption for type 1 and type 2 cements being in the range 14 to19kWh per ton (at motor terminals), and the plant auxiliaries consumption generally being from 5 to 7kWh per ton.

The results obtained on the first plants to be commissioned are plotted on Table 3, and give rise to the following points:

* For material bed grinding machines, the water demand of cement on pure paste is equal to or higher than the value found for ordinary tube mills (from 0% to 1%, more rarely to 3%, when compared to open circuit mills).

* This typical mill feature has no influence on the results when considering mortar or concrete, where the parameters are similar to those of tube mills. For example, statistics from one of the countries where the Horomill is being used for clinker grinding show that water demand for concrete was about 205 kg per m3 when cement coming from other plants employing tube mills showed water demands of between 200 and 210 kg per m3. (Average 205 kg per m cubed).

* Similarly, setting times for concrete made with cement ground in the Horomill were about 320 minutes for initial and 450 minutes for final setting. Values for ball mills ranged from 300 to 320 minutes for initial and 405 to 465 minutes for final.

This confirms that the Horomill allows the milling of "non-exotic" cement in a similar manner to conventional machines.

2, the Horomill powder whet system

The work principle that the tube Gun whet with other smash mechanical work principle a dissimilarity, the tube Gun whet is application anticipate a layer to smash a principle work of, from enter anticipate device, powder to whet to take and unload to anticipate to equip two part constitute.It of the new craft skillfully combined ball to whet with the Gun press grinding basic way of thinking and make use of medium etc. pressure, make material from feed equipments but realization at a time to for many times squeeze powder to whet.Such as figure 1 show, is whetted a material from go into anticipate a people whereabouts in a level the turn-over of the cylinder form tube body, be subjected to leave the mental exertion function even cloth in from the cylinder form tube form inside the body but composing of grinding machine of in carry, along with the turn round of tube body exercise into grinding machine with it above whet Gun to constitute of squeeze inside passage, whet Gun to depend on a liquid to press system toward grinding machine of is whetted a material to bring pressure and ask for help of to squeeze dint to cause of rub a function passively the turn-over exercise, material at squeeze inside passage complete a powder whet homework after drive promote combine through lead anticipate equip realization to whet machine export direction of exercise, accept next time squeeze powder whet a function.Squeeze powder through many times to whet machine behind of the material leave to descend the grinding machine less and anticipate to eject to whet machine from.

Tube Gun's whetting powder to whet system generally can is divided into two kinds of basic patterns: prepare powder to whet pattern, stick to match powder to whet pattern, eventually the powder whet pattern.Generally speaking, two kinds of ex- technique reformations which mainly used for privately owned powder to whet system, the second mainly used for to lately set up powder to whet system.In the fulfillment, powder grinder the choice of the skill system be mainly varied, be decided by customer's request, such as expectation of ability and condition of the characteristic, equipments of the type, product of production ability, original material, invest budget and can waste to use etc., and the tube Gun whet while operate to the request of material, such as material grain degree, glue sex etc., such as figure 6 show of the powder whet the application of system also is limited by to request small strict powder to whet to the powder body tiny view facial look so far, if living to anticipate, coal, original mineral.Currently, according to practice experience and concrete condition, make the material fly to reasonable and equipments to install reasonable, in consideration of can waste to use etc. jailbird's vegetable, thus constitute of the tube Gun whet to fully grow powder a grinder skill process, can mostly induce for from the figure 2 arrive figure 6 a few familiar forms.

From the figure 2 go to figure 6 the powder show grinder skill system the process can see and the tube Gun whets powder to whet system to have as follows several squares but characteristics:

(1)Fully grow craft process although the formality have small homology, constitute an unit homology, tube Gun's whet is the key that the whole powder whets system to constitute part.

(2)The difference of formality is the difference that the material fly to.Prepare powder to whet pattern is whet through a tube Gun of all of the material enter ball to whet machine, the stick matches powder to whet product and ball that pattern whets out from the tube Gun to whet a machine to anticipate medium qualified and thin powder from choose powder machine to select into a finished product database, the part is thick anticipate to return to tube Gun to whet:eventually the powder whet pattern is all thick anticipate to return to tube Gun to whet, in the system have no ball to whet machine existence.

(3)Fully constitute a set of dollar is on the spot and all separated certain distance, consider the customer requests to make sure that the concrete powder whets a system craft process.

Obviously, a small difference in the water demand always exists on the basis of a pure cement probe, but as there is no physical action in relation to this test, everybody, with the exception of one European country, forgets it.

Finally, the results from Horomill grinding compared to tube mills is equivalent to the difference found by users when third-generation classifiers, giving more Rosin rammler slope, began to be used causing more water demand on the pure cement probe. Third-generation classifier cement is good, even if the grain size is different from cement ground in an old grinding plant.

Raw grinding Initially, many clients were sceptical about using the new system for raw meal grinding with many being unable to understand how the moisture could be removed from the material by a non-airswept mill.

However, extensive tests conducted in Trino (Italy) and industrial tests in Tepetzingo (Mexico) have shown that the Horomill is able to efficiently dry materials with high moisture levels and that the principles involved allow efficient grinding of raw material.

The Moctezuma Tepezingo plant is now using the Horomill for both cement and raw material grinding, and the results for raw material can be seen in Table 4. On the basis of these results, another manufacturer, Galadari in Pakistan, intends to use the Horomill for grinding both cement and raw materials, when commissioning occurs next year.

Other applications Following the presentation at VDZ in 1993, the first client for the machine was a Heidelberg subsidiary, which ordered a Horomill for its SMA Faulquemont plant in France. The mill is currently grinding 12 mtph of anhydrite at 5500 Blaine. Power consumption is claimed to be three times lower than the vibratory mill used before.

Again considering anhydrite, Maxit has ordered a 40-mtph mill for Krolpa (Thuringen), which should be in full operation in the middle part of 1998.

Many suppliers of ground calcium carbonate (GCC) also have expressed an interest in the Horomill solution, and two mills have been ordered so far; one was scheduled for commissioning at the beginning of 1998.

The curves in Table 5 show the results from the Horomill grinding of different products, the substitution ratio is defined as the number of kW consumed when using a tube mill, which can be replaced by one kW using a Horomill.

Conclusion : *The item's technique is mature dependable, equipments operation steady, vibrate noise smaller, equipments maintenance convenience be easy to an operation, the Horomoll powder whets system to have higher automation level, the equipments starts procedure simple.

*Should whet machine system to be used as eventually powder to whet a system host an equipments little, the craft process is simple, decoration convenience.

*The cement powder whets an electricity to consume low, the stanza electricity's effect is outstanding.

* Make use of the Horomoll powder whets cement and tube to whet to compare various cement function index sign normal.

* Along with cooperate with French FCB company technique of further thorough, equipments manufacturing of the national product turn a rate can gradually extend, the FCB company exterior kit equipments,such as electrical engineering and lubrication system, also has gradually a possibility of convert the domestic equipments in that system.