This invention refers to an ejector-mixer device for a method for sawing hard rocks, in which the action of the cutting elements is facilitated by the incorporation to the cutting groove of grit functioning as an abradant, suspended in a sludge which acts not only as the support for the grit but also as a coolant in the cutting zone, whereas the aim of this procedure is to improve recovery of grit and particularly, to reduce the cost of such sawing (see for example ES-A-8702220).

The invention also concerns a method for sawing hard rocks using an ejector-mixer device.

The process consists of eliminating continually or intermittently part of the water with residues or sawing detritus and the lime with its derivatives where the case may be, without reaching the maximum concentration limit that allows to maintain the abradant in suspension, in other words, that the suspension of the abradant is largely due to the sawing detritus. Therefore, the sludge processing method is the factor that most limits the possibility of advancement in sawing, due to the high content of sawing detritus in the sludge, and is the cause for the excessive consumption of energy, abradant and metal strips.

Patent no. ES 9300185/PCT 9400009, among others, described the possibility of sawing with sludge containing low percentages of sawing detritus where the supporting power is due to the presence of fine, soft powders that allow to reduce the total cost of the sawing to a third and simultaneously treble the production, but this solution has not been applied yet due to the high investment needed for its application.

After that, as may be seen in Patent no. ES 9801558, there was a proposal for a method based on maintaining a high content of rock particles, pouring out part of the sludge containing the rock particles produced in the sawing, whereas this latter operation may be performed on a continuous or frequent basis, as may the replacement of adequate amounts of water, lime and fine, soft materials that have been removed from the sludge circuit.

In this patent, the composition of the sludge entering the machine, excluding the grit, would be less than 66% for rock particles, over 28% for lime water and more than 6% for fine, soft materials; with the volume and according to the characteristics of the rock to be sawed.

This patent described and claimed an installation to implement the aforementioned method, whereas the addition of the installation method allowed to improve the results in the cutting operations.

Nonetheless, the ratio between the volumes of water and fine, soft materials, in accordance with the aforementioned conditioning factors, should be approximately 3.5 to sustain the minute grains of steel and allow the latter to flow through the grooves, so that the 21% of water corresponds to 6% of fine, soft materials, meaning that the maximum volume of sawing detritus is limited to 73%, also in volume and excluding the grit.

Furthermore, the difficulty in recovering the grit from a sludge with the aforementioned proportions of fine, soft materials/ water, i.e. 3.5, in the hydrocyclones that are normally used in hard rock sawing industries is so important that the loss of grit could be excessively increased.

The present invention provides an ejector-mixer device according to claim 1 and a method for sawing hard rocks according to claim 5.

In accordance with the procedure of this invention, the grit are recovered in the sludge that is continuously or intermittently separated from the circuit to recover the rock residues that are continuously produced in the sawing process. More specifically, the invention provides for dilution of the sludge for evacuation and that it shall be re-mixed uniformly with water or lime water before passing through the hydrocyclone, whereas in this regard the amount of water used may go from one part water to three of sludge as far as more than ten parts water to one of sludge.

Moreover, the invention provides that the content of lime water in the sludge may oscillate between 21% and 28% and that the sawing detritus content may also account for between 73% and 66%.

In order to achieve correct recovery of the grit, as explained before, the invention provides for a vertical ejector-mixer, with descending flow, in which the ejected jet impacts against a horizontal wall, either regular or irregular, made of wear-resistant material, such as virgin rubber or other such material, easily replaceable by fitting and sticking; a horizontal wall situated inside a chamber with a vertical axis, preferably cylindrical and also lined with wear-resistant material; whereas on the horizontal wall and outside the impact area, there are several holes through which jets of the product pass on their way to a lower chamber, in which they also impact on a tronco-conical or tronco-pyramidal surface with an inverted vertical axis, which is also wear-resistant and defines an outlet for the mixture, where there is a waterjet or pressurised drag system, which shall preferably function after the ejector-mixer stops, for several seconds, but which could also function simultaneously with the latter if necessary.

In order to complement the description and with the aim of allowing for a better understanding of the characteristics of this invention, according to an example of the preferred embodiment of same, a single map sheet is included, representing schematically in a single figure and in an illustrative and non-restrictive manner, a side elevation and diameter section of an ejector - mixer according to the object of the present invention.

In the aforementioned figure, it may be observed that the ejector-mixer device that participates in the invention is formed by a cylindrical body (1), with a vertical axis, whose side and internal surface is covered by a layer (2) of wear-resistant material, for example, virgin rubber or other such material, whereas this body receives through its upper base (3) an ejector (4), also with a vertical axis, whereas a water injector (5) is placed coaxially opposite the latter, crossing a small chamber (6) also associated to the upper base (3) of the body (1) and to which the inlet (7) for sludge to be evacuated accesses radially.

Inside the body (1), there is a transversal partition (8) which constitutes the means of support and attachment for a bridge (9), also materialised in a piece of wear-resistant material, like the aforementioned, whereas such bridge defines a horizontal surface (10), which shall initially be flat, but in which there shall be irregularities due to the effect of the impact of the sludge on same, whereas this piece (9) shall preferably be fixed to the partition (8) with adhesive, allowing for replacement.

In the perimeter zone of the partition (8), outside the body (9), there is a circumferential line of holes (11) communicating the upper chamber (12) defined in the body (1) by the intermediate partition (8), with the lower chamber (13), the lower end of which is a tronco-conical surface (14), also with a vertical axis, defining the outlet hole (15) established in the lower base (16) of the body (1) and which establishes communication between the ejector-mixer itself and the outlet pipe (17) for the mixture.

A water injector (18) is situated on the closed end (19) of the tube (17), at the lower level, to drag the grit that might be deposited in the tube (17) and ensure their entry in the hydrocyclone in which the aforementioned tube enters (17), not represented in the figure.

In accordance with this structure, the functioning of the ejector - mixer is as follows:

The sludge enters same through the pipe (7), reaching the small input chamber (6) at an appropriate, properly regulated flow, from which it is displaced towards the ejector (4) on which the water jet generated by the injector (5) acts parallel and simultaneously, so that there is a jet that impacts at high speed on the surface (10) of the bridge (9) from which, by the effect of the slope in its route determined by the downwardly diverging configuration of the ejector (4), the mixture suffers a sudden change in its route and is directed at the lining (2) of the side wall of the body (1), thereby achieving a high degree of agitation inside the chamber (12), after which the mixture is passed to the lower chamber (13) through the holes (11), where it impacts on the slanted plane (14), producing a new agitation with the consequent increase in the homogeneity in said chamber (13), from where the mixture finally accesses, through the outlet (15), the evacuation pipe (17) towards the hydrocyclone.

Thus, more grit recovered in the said hydrocyclone and there is a reduction in the cost of sawing at the aforementioned sludge composition stages.

The ejector-mixer should be installed to function in the vertical position shown in the figure, so that the flow of the mixture may descend and it should also be situated as close as possible to the entrance to the hydrocyclone for recovery of the grit.