Method for Obtaining Microcements for Injection Grouts and Microcement Obtained

Abstract

A method for obtaining microcement and the microcement obtained thereof, by means of using a closed-circuit mill with high-efficiency separators (second generation with cyclones for dust collection), thus allowing to produce at a very low cost, showing excellent properties and quality of the microcement obtained thereof.

Claims

1. A method for obtaining microcement for injection grouts through the use of a grinding system that utilizes a mill connected to a high-efficiency separator (second generation with cyclones for dust collection), wherein the method comprises the stages of: providing raw material to the mill and grind until a determined particle size is obtained, feeding the high-efficiency separator (second generation with cyclones for dust collection) at the top part with the ground raw material, supplying the high-efficiency separator with an air current through an external fan and generating the recirculation of said air current, separating the coarse material through suction inside the main housing of the separator with the air flow or current, discharging the fine material through the top part of the housing with the air flow, moving such fine material to a plurality of cyclones through a gas conduct, separating the fine material inside the cyclones until a fraction of ultrafine material is obtained, discharging the remaining fine material through the top part of the cyclones onto aeration conveyors, moving a part of the air current together with the fraction of ultrafine material from the cyclones to a sleeve filter, and extracting such ultrafine material fraction from the filter.

2. A method for obtaining microcement according to claim 1, wherein the coarse material is discharged at the bottom part of a discharge hopper through a pendulum valve.

3. A method for obtaining microcement according to claim 1, wherein the ultrafine material is extracted from the sleeve filter by a forced air current.

4. Microcement for injection grouts of the type used in bridges, pavements, dams, prefabricated materials, foundations, stand-alone projects, tunnels, mining projects and/or oil & gas wells, which comprises: 30 to 95% by weight of Portland cement clinker, 2% to 6% by weight of plaster, and 0% to 70% by weight of limestone, slag, ash or pozzolan.

5. A microcement for injection grouts according to claim 4, which comprises: 88% by weight of Portland cement clinker, 5% by weight of plaster, and 7% by weight of limestone, slag, ash or pozzolan.

5. A microcement for injection grouts according to claim 4, which comprises: 88% by weight of Portland cement clinker, 5% by weight of plaster, and 7% by weight of limestone, slag, ash and pozzolan.

6. A microcement for injection grouts according to claims 4 and 5, wherein it presents a maximum particle size ranging between 15 and 25 microns.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0014] Referring now to the invention, it consists of a new method for obtaining microcements for injection grouts that uses grinding systems with high-efficiency separators, which allows for a more practical and efficient method taking advantage of a very fine fraction of ground cement (microcement), that if it were not extracted, it would be part of the cement obtained in the grinding, delivering a microcement with adequate properties for its application in higher value injection grouts.

[0015] Firstly, reference will be made to the known closed circuits of cement grinding with high-efficiency separators (second generation with cyclones for dust collection) for exemplary purposes and to facilitate understanding of the present invention. Therefore, the closed-circuit mills with high efficiency separators (second generation with cyclones for dust collection) have the capability of fractioning and mixing raw materials down to an adequate particle size. Subsequently, this material is fed to the separator through a distribution disk, which by means of the air current and rotation forces (gravity and centrifuge forces) makes a separation between fine and coarse particles. The coarse particles return to the mill, while the separation air current, which is mixed with the fine particles (product obtained from the grinding), goes to the dust collection system of the separator materialized by cyclones, where the air current is separated from the material (final product). Upon air extraction, ultrafine material is dragged, which finally materializes the microcement.

[0016] As mentioned above, the method of the invention is characterized by using said high-efficiency separators (second generation with cyclones for dust collection) by which the microcement is separated from the cement that is being ground. This microcement, compared with microcement produced by grinding dedicated exclusively to its production, presents an important reduction in related costs.

[0017] Thus, the method for obtaining microcement for injection grouts comprises a first stage of grinding the cement raw materials to a suitable particle size, where subsequently said material is fed through the top of the separator. Once the ground material is inside the separator, an air current is supplied through an external fan, and recirculation of said air current is generated to assure a constant flow that allows for continuous separation of coarse material from fine material as the separator is fed with raw material. The separation process from the coarse material is produced by suction inside the main housing using air flow. During the aforementioned separation, the fine material is moved and discharged at the top part of the housing with the air flow, while the coarse material falls by gravity towards the bottom of a discharge hopper and exits the same through a pendulum valve.

[0018] Referring again to the method of the invention, the fine material that arrives from the high-efficiency separator is moved to a plurality of cyclones through a gas conduct. Within the cyclones, the fine material is separated until a fraction of ultrafine material is obtained. The separation of the fine material is achieved through an air vortex generated inside the cyclones. Thus, the remaining fine material is discharged at the bottom of the cyclones onto the aeration conveyors which transport the fine material for later packaging. The remaining fine material is what known as cement. On one hand, the ultrafine fraction moves to a sleeve filter by the generated air, thereby retaining the ultrafine fraction for later extraction that is achieved through a forced air stream. It is highlighted that the ultrafine fraction that is extracted from the sleeve filter is the microcement itself.

[0019] As an example, but not limiting the scope of the invention, using a raw material feed current to the mill of 43 tph (100%), fine material is obtained, i.e., cement final product of 42.5 tph (98.8%) and ultrafine material (microcement) of 0.5 tph (2.12%).

[0020] Likewise, in another embodiment, a microcement can be obtained for injection grouts of the type used in bridges, pavements, dams, prefabricated materials, foundations, stand-alone projects, tunnels, mining projects and/or oil & gas wells, which consists of:

[0021] 30 to 95% by weight of Portland cement clinker,

[0022] 2% to 6% by weight of plaster, and

[0023] 0% to 70% by weight of limestone, slag, ash or pozzolan.

[0024] In a second embodiment, a microcement for injection grouts can be obtained using the method of the invention which consists of:

[0025] 88% by weight of Portland cement clinker,

[0026] 5% by weight of plaster, and

[0027] 7% by weight of limestone, slag, ash or pozzolan.

[0028] Given the microcement can show a maximum particle size ranging between 15 to 25 microns in said embodiments, it is highlighted that the microcement, with its respective components and percentages mentioned above, do not limit the invention. Other percentages can be used without departing from the scope of the invention.