Production process of artificial aggregate from tailings from mining, artificial aggregate, concrete composition and use

Patent metadata

Field	Value
Publication number	US-2022371956-A1
Application number	US-202017772486-A
Country	US
Kind code	A1
Filing date	Oct 30, 2020
Priority date	Oct 30, 2019
Publication date	Nov 24, 2022
Grant date	—

Abstract

The present invention relates to the process of producing artificial aggregate from tailings from ore dams. The iron ore sandy tailings are mixed with a binder and, through the mixing and pelletizing process, form the artificial aggregate. The artificial aggregate produced has a spheroidal shape, a large size, a rough surface and a color that ranges between pink and dark red. This artificial aggregate is able to replace the natural aggregate, and can be used in the manufacture of a more resistant concrete, for the base and sub-base of roads, as a decorative element for gardens and beds, in addition to being a form of storage of ore dam tailings in the form of pellets, adding value to these tailings and reducing the environmental mining impacts.

First claim

1 . An artificial aggregate production process,
comprising: (a) a providing sandy mining tailings, arranged in ore dams, with a particle size of between 0.03 and 11 mm; (b) mixing the sandy mining tailings and a binder for 30 to 60 minutes until a mixture thereof is homogeneous, wherein the binder comprises commercial pozzolan or pozzolan produced from mining sterile itself after calcination thereof mixed with CPV Portland cement, and wherein the sandy mining tailings and binder mixture has 65 to 85% by weight sandy mining tailings and 15 to 35% by weight binder; (c) pelletizing the mixture at room temperature in a pelletizing machine to form pellets, wherein forming the pellets comprises adding water sparged to a humidity of from 4 and 12% to the pelletizing machine, and wherein a residence time of the mixture in the pelletizing machine ranges from 30 to 70 minutes, considering a mass of 400 kg of the mixture; and (d) curing the pellets at room temperature for a period ranging from 1 to 14 days; wherein calcining the mining sterile of step (b) is conducted with flash technology at from 750 and 950° C. and the binder comprises a mass ratio of 25 to 30% of calcined mining sterile and 70 to 75% by weight of CPV Portland cement.

2 . The artificial aggregate production process of claim 1 , wherein the sandy mining tailings contain Goethite, Hematite, Quartz and Kaolinite, and optionally Gibbsite.

3 . The artificial aggregate production process of claim 1 , wherein the sandy mining tailings are dried after step (a) if the sandy mining tailings have a moisture content greater than 20% by weight.

4 . The artificial aggregate production process of claim 3 , wherein the drying of the sandy mining tailings is natural or in a rotary dryer used to dry river dredging sand.

5 . The artificial aggregate production process of according to claim 1 , wherein the mixing of step (b) is performed in continuous mixers if the sandy mining tailings have a has moisture content of less than 20%, the continuous mixers having a mixing chamber with a diaphragm for flow adjustment, a central rotor, paddle-type mixing utensils, and side scrapers, and wherein a rotation of the central rotor ranges from 10 to 45 rpm.

6 . The artificial aggregate production process of according to claim 1 , wherein the mixing of step (b) is performed in a pelletizer disc with adjustable edges, the sandy mining tailings and the binder being added at a same time, if the sandy mining tailings has have a moisture content of greater than 20%.

7 . The artificial aggregate production process of according to claim 1 , wherein the pelletizing machine has an adjustable height edge, with rotation from 10 to 25 rpm, disk inclination from 40 to 50°, for a period of time from 30 to 70 minutes.

8 . An artificial aggregate obtained by the process of claim 1 , wherein the artificial aggregate comprises 65 to 85% by weight sandy mining tailings and 15 to 35% by weight binder.

9 . The artificial aggregate of claim 8 , wherein the artificial aggregate has a color ranging between pink and dark red, a spherical shape, a size from 4.8 to 16 mm, a rough surface and a diameter ranging between gravel 0 (B0: −12.5 mm+4.8 mm), 00 gravel (B00: −9.5 mm+4.8 mm) and B0/B1 gravel (B0/B1: −16 mm+9.5 mm).

10 . A concrete composition comprising:
15.2 to 18.6% by weight of Portland cement; 32.8 to 34.3% by weight of natural sand; 48.5 to 50.4% by weight of the artificial aggregate of claim 8 .

11 . The concrete composition of claim 10 , wherein the concrete composition comprises natural aggregate with the artificial aggregate.

12 . The concrete composition of claim 10 , wherein a weight percentage of the artificial aggregate is divided between 25.2% by weight of gravel B0/B1(B0/B1: −16 mm+9.5 mm) and 25.2% by weight of gravel 0 (B0: −12.5 mm+4.8 mm); or 24.3% by weight of B0/B1 gravel (B0/B1: −16 mm+9.5 mm) and 24.3% by weight of gravel 0 (B0: −12.5 mm+4.8 mm); or 12.1% by weight of 00 gravel (B00: −9.5 mm+4.8 mm) and 36.4% by weight of gravel 0 (B0: −12.5 mm+4.8 mm).

13 . A method for manufacturing concrete comprising providing the artificial aggregate of claim 8 and manufacturing concrete therefrom, wherein the concrete is useable as a base and sub-base constructive element for roads, for storage of dam tailings in the form of pellets, or as a decorative element in gardens and beds.

14 . (canceled)

15 . (canceled)

Assignees

• Vale Sa
• Fund Amparo Pesquisa Estado Minas Gerais Fapemig
• Univ Federal De Minas Gerais Ufmg

Inventors

• Da Gama Evandro Moraes
• Fagundes Larissa Virgínia Queiroz
• Gomes Abdias Magalhães

Classifications

• C04B7/12

  Natural pozzuolanas; Natural pozzuolana cements; {Artificial pozzuolanas or artificial pozzuolana cements other than those obtained from waste or combustion residues, e.g. burned clay; Treating inorganic materials to improve their pozzuolanic characteristics (cements containing slag C04B7/14)} · CPC title

• Y02W30/91

  Use of waste materials as fillers for mortars or concrete · CPC title

• C04B18/12 Primary

  from quarries, mining or the like · CPC title

• C04B14/062

  Microsilica, e.g. colloïdal silica (preparing microsilica slurries or suspensions C04B18/148) · CPC title

• C04B7/525

  Briquetting · CPC title