PROCESSING

Field of the Invention

[001] The present invention refers to an improvement in the stage of magnetic concentration of mineral or ore particles by means of one or more nanomagnetic products functionalized with polysaccharides and other compounds, applied in a dosed form directly to the pulp (ore and water) aiming to modify, during magnetic concentration, some parameters of the particles, whether environmental or physical, such as magnetic susceptibility and surface chemistry, such as electrostatic attraction, whether performed selectively or not, aiming at effects on recoveries and contents of minerals and/or ores, whether magnetic and / or non-magnetic.

Background of the Invention

[002] During most of the mining history, the generation of tailings and the resulting impacts from their disposal in the environment were considered minimal. However, the Industrial Revolution brought not only an increase in the demand for mineral inputs but also, with the introduction of steam power, there was a great increase in amounts produced by exploration processes and the use of mineral substances. Therefore, the generation of tailings also increased, and to be able to be deposited and contained, it was necessary to build barriers and containment dikes (https://ibram.org.br/conteudos-tecnicos/ -accessed in 19/05/2021).

[003] The increase in iron ore production, demanded by a fast-growing world steel market, has led mining companies to constantly seek to make better use of their mineral reserves. The progressive reduction of iron content in the deposits, added to the increasingly rigid requirements of the market and the need to achieve more competitive production costs, given the fact, a frank drop in the product as it becomes imperative to study new routes for ore processing. [004] An event in Brazilian mining, also known as the Samarco disaster, took place on November 5, 2015, at the Fundao dam located in a mine environment in the city of Mariana, state of Minas Gerais. The breach had 19 fatalities and caused the flow of 32.6 million cubic meters of tailings from the structure. All this volume reached the Santarem dam, which retained a large part of that volume (https://www.samarco.com/reparacao/- accessed on 19/05/2021).

[005] The wave of mud produced by the ruptured dam, spread over several kilometers, reaching the Rio Doce, the second largest river in extension in Brazil, transforming it into a “sea” of red mud. Subsequently, Rio Doce's contaminants were discharged into the Atlantic Ocean, after traveling about 665 km, severely affecting coastal environments and marine ecosystems. In all, 39 cities in Minas Gerais and Espirito Santo were affected by the disruption and, professionally, the inventor was very close to mitigating some of the impacts of this accident, working on actions, mainly aimed at restoring the water supply system in some cities affected.

[006] 3 years after the Mariana tragedy, on January 25, 2019, another mining dam composed of iron ore tailings broke catastrophically in Brumadinho, Minas Gerais, Brazil. The rupture produced an avalanche of mud that spread over 10 km and reached the Rio Paraopeba; an important affluent of Rio Sao Francisco. Despite the volume of mud derived from the Brumadinho disaster being smaller than that of Mariana, the event caused much more significant losses of lives. In January 2020, the death toll reached 259 people and 11 individuals remained missing

[007] Because of the impact of this type of accident, studies have been carried out for the processing of tailings or ROM (Run of Mine) inducing the surface of the materials to hydrophobicity by means of collecting agents applied in the process of concentration by flotation. However, when the processing is carried out by magnetic concentration, it depends mainly on the magnetic susceptibility and the environmental magnetism of the mineral particles. Within this context, the present invention intends to contribute with options for reuse of waste and/or improvements in ROM and proposed the use of nanomagnetism applied in the magnetic concentration route as a way to selectively induce the magnetism of mineral particles and justify its processing or improvement of the process.

History

[008] Flotation today applies to virtually all types of mineral resources. Among the metallic resources, it is the basic process for the concentration of copper, lead, zinc, cadmium, cobalt, silver, molybdenum, niobium, and platinum (PGM), and it stands out considerably in terms of application for iron, nickel, terra- rare, tungsten, tin and gold. For non-metallic mineral goods, there are flotation applications for the concentration of various silicates (talc, quartz, feldspar, micas, spodumene, etc.), carbonates (calcite, magnesite, dolomite), sulfates (barite), borates, in addition, to be extremely important in the concentration of raw material suppliers for the fertilizer industry (phosphate and sylvite). Flotation is also applied for the concentration of graphite, sulfur, fluorite, and the elimination of ferrotitaniferous impurities from kaolinite. In the field of energetic materials, flotation is applied to the cleaning of coals.

[009] Magnetic separation is a concentration step, used for the separation of useful species, which can concentrate or purify them. This separation depends on the response of the mineral when subjected to a magnetic field, called magnetic susceptibility. As the market is more and more demanding, and the competition is greater, variations in the levels of iron ores in the deposits, taking into account the geological aspects, such as mineralogy and its genesis, require improvement in technologies and greater knowledge of minerals involved to obtain a product suitable for the consumer. Based on the different levels and suitable products, each ore may require a specific processing technique. There is a variety of magnetic separators on the market, with low and high-intensity separators that operate both dry and wet, they are classified according to their field strength and the material to be concentrated and/or purified. The separators are called drum, induced rollers, cross belts, carousel, etc. The choice of which equipment to use depends on several considerations, the most important being the granulometric distribution, the magnetic distribution of the material to be processed, and the capacity of the equipment.

[0010] When analyzing the current contribution of nanotechnology in mining, there are few examples of investments in research that focus on improving the processes that involve mining activity itself.

The Problem of Recovering Fine Ore

[0011] The concentration of ores by flotation shows good efficiency in a given particle size range, outside of which the recovery of fine or coarse is very low. This size range depends on the mineral species, the scale of operation, and the concentration of reagents, and fluctuates for ores of 5 pm and 150 pm. Due to the low recovery, mainly in the fine and coarse fractions, thousands of tons of high content tailings have been deposited in dams, generating operational costs, production losses, and in many cases environmental disasters. There is great interest in the sustainable exploitation of these tailings or "complex ores".

[0012] The process of magnetic concentration of mineral particles magnetically susceptible or not is carried out only through the use of magnetic field generating equipment, which can be of the type WHIMS (wet high-intensity magnetic separator), SLON (vertically pulsating high-gradient magnetic separator - VPHGMS), or others. In addition to magnetic susceptibility, other variables also interfere in the process of concentration or magnetic separation. Some are listed below:

• Specific weight;

• Degree of release

• Granulometry;

• Grain shape;

• Anisotropy.

[0013] The environmental magnetism of the particles can make the process of magnetic concentration unfeasible, in which case it is essential that mining operations involving magnetic concentration modify the physical properties together with chemical properties of mineral particles that come from the mine (ROM - run of mine) or tailings stored and/or generated from the flotation outlet (underflow), using new chemical products with magnetic characteristics to achieve environmental impacts, obtain financial viability, increase in recoveries, contents and/or reuse of materials (savings circular), the latter may be of materials of precious, non-precious and magnetic or non-magnetic origin.

[0014] US 2021/0069729 describes a process for concentrating iron sludge containing ultrafines through reverse cationic flotation with the addition of amide-amine collectors. This document also says that the process requires the use of starch, because, in the technical field of iron flotation, the starch makes the surface of the iron hydrophilic and improves the selectivity of the flotation. However, in the process of this document, starch impairs metallurgical recovery, thus moving away from the invention.

[0015] The document CN104014417 describes a process for processing ultrafine iron ore that has a step of adding a magnetic carrier that will attract the fine particles of iron ore. This magnetite, hematite, or any other iron ore with strong magnetism.

[0016] There is no state-of-the-art document that reveals or suggests the use of the functionalized nanomagnetic product described in detail below so that the present invention is endowed with novelty and inventive step.

Brief Description of the Drawings

[0017] Figure 1 represents a magnetic concentrator.

[0018] Figure 2 represents an example of a nanomagnetic chemical structure with different radicals.

[0019] Figure 3 represents an example of a matrix, where a magnetic field gradient is generated.

[0020] Figure 4 represents examples of impellers that can be used to manufacture nanomagnetic chemicals.

[0021] Figure 5 represents a mixing tank or multipurpose reactor where nanomagnetic chemicals are manufactured.

[0022] Figure 6 represents a simplified scheme of magnetic concentration with nanoparticles. [0023] Figure 7 represents a schematic representation of the magnetic concentration steps.

[0024] Figure 8 represents the particle size distribution of the sample.

Summary of the Invention

[0025] In a first aspect, the present invention describes a functionalized nanomagnetic product that allows the processing of ores.

[0026] An object of the present invention is a nanomagnetic product comprising a nanomagnetic core functionalized with organic and/or inorganic groups.

[0027] A further object of the present invention is a process for preparing a functionalized nanomagnetic product comprising the steps of: a) precipitation of Fe+2 and/or Fe+3 chloride and/or sulfate in alkaline medium; b) hydrophilization with surfactants selected from the group comprising amphoteric, anionic and/or cationic surfactants; and c) functionalization with organic and/or inorganic groups.

[0028] In a second aspect, the present invention describes a process for processing ores, extracting compounds of interest through the use of a functionalized nanomagnetic product.

[0029] An additional object of the present invention is an ore processing that comprises the steps of: a) feed a functionalized nanomagnetic product as defined in any of the claims 1 to 5 and an ore to a magnetic separator; and b) submitting the mixture to a magnetic separation process.

Detailed Description

[0030] The present invention is only intended to exemplify some of the numerous embodiments of the claimed scope and should not be seen in a restrictive way.

Funcionalized nanomagnetic product [0031] The functionalized nanomagnetic product of the present invention is composed of a nanomagnetic core which is functionalized with at least one organic and/or inorganic group.

[0032] The process for preparing a functionalized nanomagnetic product comprises the steps of: a) precipitation of Fe+2 and/or Fe+3 chloride and/or sulfate in alkaline medium; b) hydrophilization with surfactants selected from the group comprising amphoteric, anionic and/or cationic surfactants; and c) functionalization with organic and/or inorganic groups.

[0033] The base of the nanomagnetic product, that is, the nanomagnetic core is prepared in mixing tanks or multi-purpose reactors (10) using precursors of Fe2+ and Fe3+, which can be chlorides or sulfates, such as iron chloride III and/or iron chloride II and/or iron sulfate III and/or iron sulfate II by the coprecipitation method using an alkali such as sodium hydroxide (NaOH) or ammonium hydroxide (NH40H) in aqueous medium or using glycol (polyethylene glycol , ethylene glycol). A mixture of the precursors is first made and an alkali is added to this mixture under stirring for approximately 30 minutes using impellers (11) to create turbulence.

[0034] As the nanomagnetic core is naturally hydrophobic, a second step is necessary to turn it hydrophylic using an amphoteric, cationic and/or anionic surfactant.

[0035] Any amphoteric, cationic or anionic surfactant known in the art can be used in the present invention. In a preferred embodiment the product is hydrophilized using DSS. - Dioctyl Sodium Sulfosuccinate in different concentrations (between 45-75% active). Optionally, Cocoamidopropyl betaine can also be used in different active concentrations (between 20 to 50% solid content), cetyl trimethyl ammonium chloride (between 25 to 55% active) and cetyl trimethyl ammonium bromide (between 20 to 60 % active).

[0036] Examples of organic groups used in the functionalization of the nanomagnetic core include, but are not limited to, monosaccharides, oligosaccharides and polysaccharides and their derivatives, such as starch (which can be optionally modified), chitosan, glucose, cellulose (which can be optionally modified) ), syrups, synthetic polymers such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyacrylonitrile, polymethyl methacrylate, polybutadiene, polyvinyl acetate, polyvinyl alcohol, polyethyleneimine, polyacrylamide, polyacrylic acid, polyvinylpyrrolidone, sodium polyacrylate polyesters such as polyethylene terephtalate, polybutylene terephthalate and polycarbonate, polyamides such as nylon, polyacetals such as polyoxymethylene, polysulfone, and their copolymers, carboxylates (COOH), hydroxy (-OH), ethers (-OR) or esters (COOR) where R is an alkyl, alkenyl or alkynyl group of 1 to 10 carbon atoms, saturated or unsaturated, -COH, primary, secondary or tertiary amines. Examples of inorganic groups include, but are not limited to, silicates and silicon derivatives (6), and nitrogenated compounds. Figure 2 illustrates a functionalized nanomagnetic product according to the present invention.

[0037] Preferably, the use of solutions of organic groups as polysaccharide derivative of the type corn gritz, corn starch or cassava starch (modified or not), chitosan, glucose, cellulose (and its hydroxy and carboxy derivatives), maltose syrups, oleaginous (corn oil, rice oil, canola oil, soy oil, cotton oil, palm kernel oil, olive oil), vegetable fats and their oleochemical derivatives (esters, surfactants) and also the use of petroleum-based synthetic polymers (methyl polymethacrylate, polyethylene , polypropylene) and PVA base (polyvinyl alcohol), provide a rheology gain in aqueous medium or glycol, useful to keep the solid magnetic particles in suspension.

[0038] Lastly, the preservation of the product against fungi, bacteria and yeasts is achieved by using a common preservative of the prior art, such as parabens, thiazolinones or formaldehyde.

[0039] The entire product can be manufactured using mixing tanks or multi-purpose reactors (10) using impellers (11 ) and unitary operations of mixing, cooling, heating, pumping and filtering, common to a person skilled in the art.

Ore Processing [0040] For the purposes of the present invention, the word "ore" encompasses any and all ores or contaminants of interest present in the mixture used at the beginning of the process.

[0041] The ore processing of the present invention generates a concentrate and tailings, and both products can be used again in the process as feeds, falling within the definition of "ore". In addition, the concentrate or tailings used as feed in the process of the present invention can also come from processes other than that described in the present invention.

[0042] Specifically, the ore processing comprises the steps of: a) feed a functionalized nanomagnetic product as defined in any of the claims 1 to 5 and an ore to a magnetic separator; and b) submitting the mixture to a magnetic separation process.

[0043] After selecting the ore to be used, it must be selected a magnetic field generator (2) and (3) capable of concentrating or magnetically separating mineral particles with or without environmental magnetic properties, these mineral particles may originate from dam or pit tailings, tailing generation or coming from the mine (ROM - Run of mine). It can also be in the form of pulp (ore and water) in different concentrations of solid matter.

[0044] This raw material has a preliminary stage of technological characterization, elementary analysis by X-ray fluorescence, X-ray diffraction of the ore or mineral sample, laser granulometry and magnetic susceptibility analysis, to record the initial data for the purpose of comparison with the result.

[0045] The feeding stage (1) may contain a stirring system with impellers (11) capable of providing turbulence so that mineral particles and nanomagnetic products (5) are adhered to magnetic or non-magnetic mineral particles, wherein the nanomagnetic products are manufactured in mixing tanks or multi-purpose reactors (10) which can use different impellers (11), heating, cooling, re-circulation, packaging, coils or baffles.

[0046] The magnetic concentrate obtained at the output of the equipment (4) can have its elements analyzed via microscopy or diffraction, and can still be magnetically concentrated again as feed in the Cleaner step after the first step, in the Rougher step, to be redirected to the concentration plant to deslurry , dried, stacked, dewatered and filtered, or to be packed in geotextile bags.

[0047] The non-magnetic tailings obtained at the equipment outlet (4) can have their elements analyzed via microscopy or diffraction, and can still be magnetically concentrated as feed in the Scavenger step after the first stage, Rougher, redirected to the concentration plant, to deslurry, dried, stacked, dewatered and filtered, or packed in geotextile bags. Figure 7 illustrates how these three steps (cleaner, rougher and scavenger) are related. The ore processing is the same in all stages, changing only the content of the raw material.

[0048] With reference to Figures 1 to 3, it is possible to observe the pulp feed reservoir or tank (1), equipped with a mixing and agitation system where the pulp (ore and water) is added and can be made of metallic or plastic material, it is also in this tank that is dosed the magnetic product that is composed of nanomagnetism (5), and a group that for example can be organic, such as a starch (8) modified or not, a carboxylate group (9) an amine (7) or an inorganic group, such as a silicon derivative (6). The result of this mixture between the pulp (ore and water) with nanomagnetic product will be directed to the magnetic field lines generated at the poles (2) and (3) that have an internal steel matrix (9) through which the ore travels through the flow that can be of the circular, straight or "sawtooth" type, or even be free of matrices (Open gap), and finally the magnetic or non-magnetic ore is directed by gravity or pumping at the outlet of the magnetic concentrator (4) to be directed to dewatering and subsequent chemical and elementary analysis.

Examples

[0049] Samples of tailings analyzed by laser diffraction (LALLS) are shown in Figure 8.

[0050] It is observed in Figure 8 the particle size distribution of the sample, particles up to about 178 mm (size pm) represent about 90% of the sample volume (Vol.Under%). [0051] Table 1 shows the results of XRD, where the presence of the hematite phase (Fe203) is observed.

Table 1 : Phase identification by X-ray diffraction (XRD)

[0052] Table 2 shows the modal distribution of the minerals contained in the sample of tailings in percentage by XRF, the contents presented were measured in a pressed sample, in the STD-1 (Standardless) calibration relative to the analysis without standards of the chemical elements comprised between the uranium fluorine. The loss to fire (PF) was carried out at 1020°C for 2h.

Tabela 2: Chemical analysis by X-ray fluorescence (XRF)

[0053] It was observed through table 2 that the content of the contaminant hematite (Fe2C>3) analyzed is present in the elemental form in 17.20% of the tailings sample. The WHC-01 B, a Wet High Intensity Magnetic Separator (WHIMS) type magnetic concentrator (WHIMS), was used. The operating principle of this equipment consists of the circulation of electric current induced between the poles of the coils, resulting in a high gradient and intensity of the electromagnetic field in the separation zone, the equipment used for the tests consists mainly of a magnetic field generating coil (8000, 10000 and 13800 Gauss) and grooved plate type matrices (1.5 and 2.5 mm).

[0054] As illustrated in figure 6, a functionalized nanomagnetic product with unmodified corn starch (Amidex® 3001 , manufactured by Ingredion) was added to the slurry or pulp (ore and water), stirred for 2 minutes and feeded to the high-field magnetic field concentrator. Upon entering the separation zone a certain amount of mass called magnetic concentrate is attracted to the surface of the matrix, and under gravity combined with hydrodynamics the rest is discarded from the process as non-magnetic tailing. Then the material is filtered under pressure, dried in an oven at 110°C, sieved, weighed, packaged and sent for analysis of X-ray fluorescence and atomic absorption spectrometry for elements that contain a lower detection range (for example Cadmium).

[0055] The magnetic concentration tests were planned in the “rougher” stage, that is, an initial stage of any ore treatment operation where concentrates and tailings of contents supposedly still unacceptable are produced and, therefore, depending on, need to be reprocessed respectively in the later stages called “cleaner” and “scavenger”. The steps are illustrated in figure 7, where the tailings were classified as new feed.

[0056] The results of the magnetic concentration tests using the tailings (new feed) are listed below in table 3.

Table 3: Result of variations of the hematite contaminant Scavenger

Scavenger 60% 25%

Concentrate

[0057] Table 3 shows that the addition of the functionalized nanomagnetic product provided, for the Rougher step, a 5% increase in the hematite content, a 25% increase in mass recovery and a 30% increase in metallurgical recovery when compared to the same process performed without the addition of functionalized nanomagnetic product. These results prove the unexpected and not obvious effect of the product and processes of the present invention