Collector reagent for optimising the recovery of metal sulfide particles in flotation processes and method for obtaining same from tyre pyrolysis oil

Abstract

The present invention relates to a formulation and method for a collector reagent obtained from pyrolysis oil from end-of-life (EOL) tyres, designed to optimise the hydrophobicity of metal sulfide particles and to be used as a collector reagent in flotation processes, with a circular economy approach for the mining industry. The invention addresses the challenges associated with the use and refining of pyrolysis oil obtained from recycling EOL tyres, advantageously leading to greater overall recovery of metal sulfides of interest than the collector reagents traditionally used.

Description

[0001] Collector reagent to optimize the recovery of metal sulfide particles in flotation processes, and a method for obtaining it from tire pyrolysis oil.

[0002] State of the art

[0003] The mining industry faces a growing challenge due to declining ore grades as deposits age. This affects the extraction, separation, and refining processes of the minerals of interest, as they must become increasingly efficient to maintain sustainable production.

[0004] In this regard, flotation is the most widely used mineral concentration method in the mining industry. Specifically, in copper mining, it is used to recover sulfide minerals such as chalcopyrite (CuFeS2) and bornite (CusFeS4). Furthermore, this process allows for the recovery of other valuable minerals, such as molybdenum, present in sulfide compounds like molybdenite (MoS2). The concentration of mineral particles occurs through the selective adhesion of gas bubbles to valuable hydrophobic particles that repel water from their surface. This forms particle-bubble aggregates with a significantly lower apparent density than water, allowing them to float on the pulp and promoting the formation of a froth containing a concentrate rich in the desired elements.Non-valuable particles, or gangue, are removed through the flotation tailings [1, 2]. To optimize the recovery of valuable particles, various specific reagents can be used, which, according to their function, are divided into collectors, frothers, modifiers, and depressants. Collector reagents are fundamental in the adsorption process of valuable minerals [3], as they provide or enhance the hydrophobic properties of the particles, forming a coating that significantly increases hydrophobicity. As a result, the selective separation of minerals in the flotation process is improved.Depending on their chemical nature, collectors can be classified as nonpolar, anionic, and cationic

[0001] . Nonpolar collectors are simple hydrocarbon oils (such as diesel), while anionic and cationic collectors have a polar part that selectively adsorbs onto the surface of the particles and a nonpolar part that extends into the solution, generating a hydrophobic coating. Anionic or cationic collectors can adhere to the mineral surface through chemical bonds (chemisorption) or through physical processes (physisorption) [4].

[0005] As mentioned previously, the extraction and production of copper and molybdenum primarily comes from porphyry copper deposits, whose most common polymetallic sulfide minerals are chalcopyrite, molybdenite, and pyrite. For these minerals, oily collectors are commonly used to promote flotation and gangue separation [5]. Specifically, hydrocarbon oils are the most common collectors for molybdenite, including kerosene, diesel, and transformer oil, among others [6]. However, petroleum hydrocarbons differ in their effectiveness at enhancing the natural floatability of molybdenite, depending on their chemical nature [5-8]. Specifically, evidence has shown that the collection and separation capacity of hydrocarbon oils is affected by the aromaticity [8] and chain length of the hydrocarbons [6,7].improving the collection capacity of molybdenite and chalcopyrite in the flotation stages when using fractions rich in aromatic and / or naphthenic compounds [7], and that a mixture of high molecular weight components with a low molecular weight diluent improves the collecting properties for molybdenite [7],

[0006] At the production level, diesel is the widely used collector in the copper mining industry [9], which has an average aliphatic composition of 75 wt%, with a chain length of 10 to 15 carbon atoms and 25 wt% aromatic compounds

[0010] . The amount of diesel used in the flotation stage can vary depending on the mineralogy of the materials, and the values ​​fluctuate between 10-100 g. 1[1, 6, 9, 11] and it is estimated that most of the reagent used is discharged into tailings ponds. These can cause problems by contaminating nearby water resources, due to inadequate tailings dam design

[0012] . This is because they are highly toxic, highly flammable, and can decompose into toxic gases such as carbon disulfide (CS2), with documented adverse health effects

[0013] . In addition, xanthate, another reagent used as a collector, has been shown to be highly toxic to aquatic life

[0014] . The most comprehensive patent related to a collector similar to the one developed in the present invention is detailed below.International patent WO2017116542A1, granted to Chevron Phillips Chemical Company LP and filed by Jim Byers

[0015] , describes a process for metal recovery using a collector whose composition contains sulfur in the form of branched C10 mercaptans and branched C20 sulfides, represented by the structure R1-S-R2, in which R1 and R2 are olefin-derived functional groups. The patent is covered in Australia (AU 2016382447 B2) and Chile (201801770).

[0007] Beyond the above, there is a push within the mining industry to minimize the environmental and occupational health impacts on all stakeholders in the production process. This has led to a need to find new chemical agents that meet the technical and economic requirements of current processes, maximizing their benefits and minimizing potentially harmful side effects for humans and the environment.

[0008] Tire pyrolysis and pyrolytic oil refining

[0009] Globally, it is estimated that by 2023 approximately 1 trillion tires will reach the end of their useful life annually

[0016] , and about 75% of these will accumulate in landfills [16,17]. End-of-life tires (ELTs) pose a problem because their degradation is extremely slow; the empty space in a tire is close to 75% of its volume, so their accumulation leads to the excessive use of highly underutilized land. Furthermore, in the event of a fire, it is difficult to extinguish the flames using conventional landfill methods

[0018] . The composition of tires varies depending on their use, but they are mainly composed of natural rubber, synthetic rubbers, black carbon, steel, and other materials such as fibers and stabilizers for the vulcanization process, which involves sulfur compounds

[0019] . In the case of light vehicle tires, the composition varies between 14 and 22 wt.% of natural rubber and 27-23 wt.% of synthetic rubber.% of synthetic rubber, while for heavy vehicles, tires have a higher percentage of natural rubber, with values ​​close to 30 wt.%, and 15 wt.% of synthetic rubber. Among the emerging technologies for the recovery and recycling of end-of-life tires, the pyrolysis process, which consists of the thermal decomposition of materials in the absence of air, is a technology that has developed potential for generating new products from end-of-life tires. In general terms, the following products are obtained from the tire pyrolysis process: (1) carbon-rich solid material, (2) steel, (3) liquid with a high percentage of aromatic hydrocarbon compounds, known as pyro-oil or pyrolysis oil (TPO), and (4) non-condensable gases.The proportion and chemical composition of the products depends on several factors, the most relevant being the reactor heating temperature, final temperature, residence time, particle size, and the composition of the raw material.

[0010] In particular, pyrolytic liquid, or TPO, is a viscous, dark liquid with a rather intense and unpleasant odor

[0020] , composed mainly of saturated and unsaturated long-chain hydrocarbons, as well as aromatic and naphthenic hydrocarbons. Specifically, TPO exhibits high concentrations of chemical compounds of significant interest, such as isoprene, styrene, and limonene

[0021] . Furthermore, it has properties similar to diesel, including a calorific value of approximately 40 MJ / kg. 1

[0022] , therefore it also has high appeal as a fuel [21-23]. However, due to the vulcanization process, TPO has a high sulfur content, which makes it difficult to use as a fuel given the high SOx emissions [20,21,23]. In addition, the pyrolytic liquid has a high content of unsaturated hydrocarbons, which limits its stability

[0020] .

[0011] In this regard, various TPO desulfurization techniques have been investigated to make it a viable substance for use in combustion engines by reducing the amount of sulfur. Hydrated desulfurization (HDS) is the most researched, given its sulfur removal via H2S formation [20, 23-25]. Among the industrial processes related to TPO HDS is patent US6402940B1, granted to Unipure Corp.

[0026] , which covers the HDS of liquid hydrocarbons. On the other hand, alternative techniques such as oxidative desulfurization (ODS), investigated as an alternative for deep desulfurization of diesel [25, 27, 28], are not as promising for TPO as a fuel because they oxidize sulfur compounds instead of removing them

[0023] . However, they open up possibilities for other uses, such as the one presented in this invention. Specifically, ODS is a chemical process in which sulfur compounds are oxidized.It consists of the addition of an oxidizing agent such as hydrogen peroxide, sulfuric acid, or another inorganic or organic acid

[0029] , and can be catalyzed by the addition of acid groups (in the liquid or solid state), generally carried out in an acidic medium. This oxidation converts organosulfur compounds that are difficult to hydrogenate, such as sulfides and thiophenes, into polar compounds with a higher degree of oxidation, such as sulfoxides or sulfones [27,30], as illustrated in Figure 1.

[0012] Oxidation is carried out under controlled temperature conditions, ranging from room temperature to 100 °C (depending on the substance), at atmospheric pressure or slightly higher. Once the sulfur compounds have been oxidized, they are generally separated due to their physicochemical differences. These processes may involve the use of solvents to dissolve and extract the oxidized compounds, or distillation methods, taking advantage of their different boiling points, among other separation methods. In this regard, a patent related to this process is the one granted to Unipure Corp

[0031] , which covers the removal of small quantities of organosulfur compounds from fuel hydrocarbons using a solution of formic acid and small amounts of hydrogen peroxide.

[0013] US patent 20090242459A1, granted to General Electric Co.

[0032] , involves the oxidation of fuel oils using hydrogen peroxide, a water-soluble acid, and a binary catalyst at temperatures between 100 and 250 °C and pressures between 1 and 172 bar, the addition of water to generate a two-phase solution, and the separation of the phases to obtain a refined fuel oil. US patent 20070051667A1, granted to Saudi Arabian Oil Co.

[0033] involves the removal of sulfur compounds from diesel fuel by a combination of: (1) an oxidation process in which the diesel fuel is mixed with oxidizing agents selected as sulfuric acid, peracetic acid, hydrogen peroxide, sodium hypochlorite, perchloric acid, nitric acid, sodium or potassium peroxydisulfate, or peroxymonosulfate, or a combination thereof, in the presence of a homogeneous or heterogeneous oxidizing catalyst at a temperature range of 50 to 150 °C for a period of time sufficient to oxidize the sulfur compounds; and (2) removal of the oxidized sulfur compounds from the diesel fuel by countercurrent extraction with a water-soluble polar solvent. Patent W02012033780A1, granted to Saudi Arabian Oil Co.

[0034] involves the upgrading of a hydrocarbon feedstock, and involves the following steps: (1) feeding the hydrocarbon feedstock into an oxidation reactor, which involves oxidizing agents such as air, oxygen, nitrogen oxides, peroxides, hydroperoxides, organic acids, or a combination thereof, the utilization of metal oxides of the form M. x EITHER y(1) wherein M is any element of group IVB, VB, or VIB of the periodic table, in a reactor at a temperature between 20–150 °C and a pressure between 1–10 bar, and an oxidizing agent to sulfur compound ratio between 4:1 and 10:1; and (2) the separation of hydrocarbons from the oxidized sulfur compounds by solvent extraction, which may involve polar solvents such as acetonitrile, methanol, acetone, or another polar organic solvent, and carried out at a temperature range between 20–60 °C and a pressure between 1–10 bar. It also involves the use of an adsorption column loaded with a suitable material for the removal of the oxidized compounds present in the extracted hydrocarbon stream.

[0014] Regarding the specific improvement of pyrolytic oil from ODS, no related patents were found. The most similar patent was US11959026B2, granted to Ruifeiniti Co Ltd.

[0035] , which focuses on improving pyrolytic oil derived from plastics or rubber, or a combination of both, by treating it with an aqueous solution and optionally a hydrocarbon fluid to form an organic and an aqueous phase, separate them, and consequently improve the pyrolytic oil. This patent details that the process leads to a reduction of oxygenated sulfur compounds in the organic phase.

[0015] In summary, the technical problem solved by this invention focuses on two key aspects. First, it addresses the improvement of recovery processes in the flotation stage of mining, which is especially relevant due to the decline in ore grade as deposits age. Second, it responds to the mining industry's need to adopt environmentally sustainable technologies. In this context, the present invention improves the recovery of metal sulfides of interest by using a collector reagent derived from the products obtained from tire pyrolysis, thereby promoting a circular economy approach and reducing environmental impact.

[0016] BRIEF DESCRIPTION OF THE FIGURES

[0017] Mistake! Reference source not found.

[0018] Mistake! Reference source not found.

[0019] Mistake! Reference source not found.

[0020] Mistake! Reference source not found.

[0021] Error! Reference source not found.

[0022] REFERENCIAS

[0023] [1] Bulatovic SM. Handbook of flotation reagents: chemistry, theory and practice. 1st ed. Amsterdam; Boston: Elsevier; 2007.

[0024] [2] Arcos F, Uribe L. Evaluation of the Use of Recycled Vegetable Oil as a Collector Reagent in the Flotation of Copper Sulfide Minerals Using Seawater. Recycling 2021 ;6:5. https: / / doi.Org / 10.3390 / recycling6010005.

[0025] [3] Rezaei R, Massinaei M, Zeraatkar Moghaddam A. Removal of the residual xanthate from flotation plant tailings using modified bentonite. Miner Eng 2018; 119:1-10. https: / / doi.Org / 10.1016 / j.mineng.2018.01.012.

[0026] [4] Rao SR. Surface Chemistry of Froth Flotation: Volume 1 : Fundamentals. Springer Science & Business Media; 2003.

[0027] [5] Castro S, Lopez-Valdivieso A, Laskowski JS. Review of the flotation of molybdenite. Part I: Surface properties and floatability. Int J Miner Process 2016; 148:48-58. https: / / doi.Org / 10.1016 / j.minpro.2016.01 .003.

[0028] [6] Lin Q, Gu G, Wang H, Liu Y, Wang C, Fu J, et al. Recovery of molybdenum and copper from porphyry ore via iso-flotability flotation. Trans Nonferrous Met Soc China 2017;27:2260-71 . https: / / doi.Org / 10.1016 / S1003-6326(17)60252-8.

[0029] [7] Smit FJ, Bhasin AK. Relationship of petroleum hydrocarbon characteristics and molybdenite flotation. Int J Miner Process 1985;15:19-40. https: / / doi.Org / 10.1016 / 0301 -7516(85)90021 -3.

[0030] [8] Li L, Li S, Gao L, Chai N, Chao Y, Cao Y. Influence mechanism of a compound collector from coal tar and dodecane in the flotation of fine molybdenite particles. Miner Eng 2023;202: 108242. https: / / doi.Org / 10.1016 / j.mineng.2023.108242.

[0031] [9] Comi T, Garcia C, Potulsha A, Opazo JJ. Chile’s new copper-molybdenum operation n.d.

[0032]

[0010] Schobert H. Chemistry of Fossil Fuels and Biofuels. 1st ed. Cambridge University Press; 2013. https: / / doi.org / 10.1017 / CB09780511844188.

[0033]

[0011] Amelunxen P, Amelunxen R. MOLY PLANT DESIGN CONSIDERATIONS 2009.

[0034]

[0012] Zhang X, Du H, Wang X, Miller JD. Surface chemistry considerations in the flotation of rare-earth and other semisoluble salt minerals. Min Metall Explor 2013;30:24-37. https: / / doi.Org / 10.1007 / BF03402338.

[0035]

[0013] Ellis J. Analysis of accidents and incidents occurring during transport of packaged dangerous goods by sea. Saf Sci 2011 ;49:1231-7. https: / / doi.Org / 10.1016 / j.ssci.2011 .04.004.

[0036]

[0014] Bararunyeretse P, Mpawenayo PC, Niyoyitungiye L, Buhungu S. Essentiality, Fate, Ecotoxicity, and Health Effects of Xanthates and Xanthates Based- Compounds — A Review. J Geosci Environ Prot 2022;10:161-203. https: / / doi.Org / 10.4236 / gep.2022.1012011 .

[0037]

[0015] Byers J, Matson M, Kreider J. Mixed decyl mercaptans compositions and use thereof as mining chemical collectors. WO2017116542A1 , 2017.

[0016] End-of-Life Tires (ELTs). World Bus Counc Sustain Dev WBCSD n.d. https: / / www.wbcsd.org / Sector-Projects / Tire-lndustry-Project / End-of-Life-Tires- ELTs (accessed May 16, 2024).

[0038]

[0017] Ferdous W, Manalo A, Siddique R, Mendis P, Zhuge Y, Wong HS, et al.

[0039] Recycling of landfill wastes (tyres, plastics and glass) in construction - A review on global waste generation, performance, application and future opportunities. Resour Conserv Recycl 2021 ; 173: 105745. https: / / doi.Org / 10.1016 / j.resconrec.2021 .105745.

[0040]

[0018] Zhang G, Chen F, Zhang Y, Zhao L, Chen J, Cao L, et al. Properties and utilization of waste tire pyrolysis oil: A mini review. Fuel Process Technol 2021 ;211 : 106582. https: / / doi.Org / 10.1016 / j.fuproc.2020.106582.

[0041]

[0019] Sienkiewicz M, Kucinska-Lipka J, Janik H, Balas A. Progress in used tyres management in the European Union: A review. Waste Manag 2012;32:1742-51. https: / / doi.Org / 10.1016 / j.wasman.2O12.05.010.

[0042]

[0020] D^bek C. Modification of Pyrolytic Oil from Waste Tyres as a Promising Method for Light Fuel Production. Materials 2019; 12:880. https: / / doi.Org / 10.3390 / ma12060880.

[0043]

[0021] Arabiourrutia M, Lopez G, Artetxe M, Alvarez J, Bilbao J, Olazar M. Waste tyre valorization by catalytic pyrolysis - A review. Renew Sustain Energy Rev 2020; 129: 109932. https: / / doi.Org / 10.1016 / j.rser.2020.109932.

[0044]

[0022] Arya S, Sharma A, Rawat M, Agrawal A. Tyre pyrolysis oil as an alternative fuel: A review. Mater Today Proc 2020;28:2481-4. https: / / doi.Org / 10.1016 / j.matpr.2020.04.797.

[0045]

[0023] Mello M, Rutto H, Seodigeng T. Waste tire pyrolysis and desulfurization of tire pyrolytic oil (TPO) - A review. J Air Waste Manag Assoc 2023;73:159-77. https: / / doi.Org / 10.1080 / 10962247.2022.2136781 .

[0046]

[0024] Toteva V, Stanulov K. Waste tires pyrolysis oil as a source of energy: Methods for refining. Prog Rubber Plast Recycl Technol 2020;36:143-58. https: / / doi.Org / 10.1177 / 1477760619895026.

[0047]

[0025] Rajendran A, Cui T, Fan H, Yang Z, Feng J, Li W. A comprehensive review on oxidative desulfurization catalysts targeting clean energy and environment. J Mater Chem A 2020;8:2246-85. https: / / doi.org / 10.1039 / C9TA12555H.

[0048]

[0026] Levy RE, Rappas AS, Sudhakar C, Nero VP, Decanio SJ. Hydrodesulfurization of oxidized sulfur compounds in liquid hydrocarbons. US20030094400A1 , 2003.

[0049]

[0027] Al-Shahrani F, Xiao T, Llewellyn SA, Barn S, Jiang Z, Shi H, et al. Desulfurization of diesel via the H2O2 oxidation of aromatic sulfides to sulfones using a tungstate catalyst. Appl Catal B Environ 2007;73:311 -6. https: / / doi.Org / 10.1016 / j.apcatb.2006.12.016.

[0050]

[0028] Dehkordi AM, Sobati MA, Nazem MA. Oxidative Desulfurization of Nonhydrotreated Kerosene Using Hydrogen Peroxide and Acetic Acid. Chin J Chem Eng 2009; 17:869-74. https: / / doi.Org / 10.1016 / S1004-9541 (08)60289-X.

[0029] Yu G, Lu S, Chen H, Zhu Z. Diesel fuel desulfurization with hydrogen peroxide promoted by formic acid and catalyzed by activated carbon. Carbon 2005;43:2285- 94. https: / / doi.Org / 10.1016 / j.carbon.2005.04.008.

[0051]

[0030] Bokare AD, Choi W. Bicarbonate-induced activation of H 2 0 2 for metal-free oxidative desulfurization. J Hazard Mater 2016;304:313-9. https: / / doi.Org / 10.1016 / j.jhazmat.2O15.10.063.

[0052]

[0031] Rappas AS. Process for removing low amounts of organic sulfur from hydrocarbon fuels. US6402940B1 , 2002.

[0053]

[0032] Soloveichik GL, Bablin JM. Oxidative desulfurization of fuel oil. US20090242459A1 , 2009.

[0054]

[0033] Martinie G, Al-Shahrani F, Dabbousi B. Diesel oil desulfurization by oxidation and extraction. US20070051667A1 , 2007.

[0055]

[0034] Bourane A, Koseoglu OR, Kressmann S. Process for oxidative desulfurization and sulfone disposal using solvent extraction. W02012033780A1 , 2012.

[0056]

[0035] ZHANG Z, WILLIAMS BP. Process of upgrading a pyrolysis oil and upgrading solution used therein. US11959026B2, 2024.

[0057] DESCRIPCIÓN DE LA INVENCIÓN

[0058] The present invention focuses on a collector reagent obtained from the thermochemical decomposition of end-of-life tires (ELTs), designed to optimize the recovery of metallic sulfide particles and increase the selectivity of the collector-mineral complex in the flotation process; and a method for obtaining it, which encompasses both the pyrolysis process and the refining process of the former using an oxidizing agent. Advantageously, the use of this collector leads to a greater overall recovery of copper, between 2 and 4 percentage points, and of molybdenum, increased between 5 and 15 percentage points, compared to diesel, the latter being the collector reagent traditionally used in flotation processes for metallic sulfide mining.

[0059] The performance of the invention depends on the chemical composition of the pyrolytic oil derived from NFUs, which is highly dependent on the pyrolysis conditions. The main control parameters are temperature, heating rate, particle size, raw material composition, and operating time.

[0060] In this context, the NFU pyrolysis process is carried out in batches by loading rotary kilns, with a feed of 10 tons per day, with the following operating ranges:

[0061] 1.- Origin of tires: the origin of the tires varies between 100 - 60% OTR, corresponding to agricultural or mining tires, and 0 - 40% PCR, corresponding to passenger tires.

[0062] 2.- Pyrolysis temperature and time: The final temperature range in the pyrolysis reactor varies between 350 - 550 °C, which is maintained for a range of 1 to 4 hours, with a heating rate from ambient temperature to the final temperature between 2 - 10 °C min' 1 .

[0063] 3.- Pressure: Slightly higher than atmospheric pressure with a range between 1 to 1.5 atm.

[0064] 4. Products and Yields: The products of NFU pyrolysis are pyrolytic oil with a carbon content ranging from 40 to 50 wt.%, carbonaceous material ranging from 22 to 32 wt.%, 17 wt.% steel, and non-condensable gases corresponding to 1.1 wt.%. The characteristics of the pyrolytic oil obtained from the process described above are detailed in Table 1. It is observed that it is a liquid with a high carbon content, which varies between 68.9 and 86.2 wt.%, and an oxygen content between 1.9 and 18.4 wt.%, which affects the heat of combustion of the product, which varies between 43.9 and 45.8 MJ / kg. -1Gas chromatography-mass spectrometry (GC-MS) analysis shows that the pyrolytic liquid is primarily composed of aromatic compounds, representing approximately 80% of its composition, with limonene being the main component at concentrations between 15 and 20 wt%. Additionally, aliphatic compounds, with chain lengths ranging from 7 to 16 carbon atoms, constitute approximately 13 wt%., followed by nitrile compounds at 2 wt%., and sulfur compounds derived from benzothiophenes at approximately 1 wt%. These characteristics position the pyrolytic oil as a potential alternative for use as a flotation agent. However, its sulfur content of approximately 1%, derived from benzothiophenes, is a limiting factor due to its composition.

[0065] Table 1 Characterization of pyrolytic oil obtained from the pyrolysis of tires under the described conditions.

[0066] Parameter Unit of measurement Value

[0067] Carbon wt. % 68.9 - 86.2

[0068] Hydrogen wt. % 9.6 - 10.3

[0069] Oxygen wt. % 18.4 - 1.9

[0070] Nitrogen wt. % 0.9 - 1.4

[0071] Sulfur wt. % 0.3 - 1.1

[0072] Aromatics wt. %

[0073] Aliphatic wt. % 7 - 18

[0074] Heat of combustion 43.9 - 45.8

[0075] Density (15°C) kg m' 3 870 - 890

[0076] V

[0077] (4 is 0c o C os) kinematics mm 2 ? s -1 „ . 1.25 - 1.45 c

[0078] Flash point °C 20 - 35

[0079] Additionally, the flash point near room temperature and the inherently unpleasant odor due to the presence of sulfur compounds, such as thiophene derivatives, in pyrolytic oil obtained from tires pose a risk to its use, transport, and safe storage. Based on this, the following method was developed to address the limitations of pyrolytic oil, which involves adding an oxidizing agent to the oil to oxidize the sulfur compounds.

[0080] 1 Addition of between 1-20 wt. % of oxidizing agent (e.g. sulfuric acid) to the pyrolytic oil, under mechanical stirring conditions with a shear rate between 800 and 2000 s -1 , and a percentage feed rate of the oxidizing agent between 0.1 and 2% per minute of the total reactor volume.

[0081] 2.- Reaction temperature between 20°C and 80°C, depending on the flash point of the pyrolytic oil, which is maintained until the desired conversion of the sulfur compounds.

[0082] 3.- The addition of an oxidizing agent may lead to phase separation, which can be improved by the addition of suitable polar solvents and phase extraction processes, including decantation processes, co-current extraction processes, countercurrent extraction processes, or other polarity-based phase separation processes.

[0083] The refined product has a higher flash point and eliminates unpleasant odors due to the treatment used. Furthermore, the oxidative desulfurization (ODS) process allows the conversion of sulfur groups present in pyrolytic oil from NFUs to obtain sulfone and / or sulfoxide groups, which are stable, polar compounds with surfactant properties, of interest in the flotation process of copper and molybdenum sulfide minerals.

[0084] Table 2 describes the main characteristics of the refined product using this method with sulfuric acid at a ratio of 1:10 and 60°C for 2 hours, separating the phases formed by decantation, in which the light fraction is the fraction of interest, which corresponds to about 70 wt. % of the initial product.

[0085] This fraction, characterized by GC-MS, shows that the hydrocarbon mixture contains approximately 76.7 wt.% aromatics, most of which are benzene derivatives with methyl or ethyl substituents resulting from the oxidation of limonene. The next largest group consists of aliphatic compounds, representing approximately 16.7 wt.% of the detected compounds, with chains ranging from 7 to 18 carbon atoms. Finally, 4.3 wt.% of the detected compounds are naphthenes.

[0086] Table 2 Characterization of the pyrolytic oil refined from oxidative desulfurization with sulfuric acid.

[0087] Parameter Unit of measurement Value

[0088] Carbon wt. % 78.2 - 86.6

[0089] Hydrogen wt. % 10.3 - 12.4

[0090] Oxygen wt. % 2.1 - 6.8

[0091] Nitrogen wt. % 0.1 - 1.0

[0092] Sulfur wt. % 0.9 - 1.6

[0093] Aromatics wt. %

[0094] Aliphatic wt. % 10 - 20

[0095] Density (15°C) 890 - 950

[0096] Kinematic viscosity 21 oo

[0097] (40"C) mm S 8 3

[0098] Flashpoint

[0099] Thus, the pyrolytic oil refined by the method described above preferably comprises an amount of aromatic compounds within a range of 65 to 85 wt.%, and a percentage of aliphatics within a range of 10 to 20 wt.%, and more preferably close to 77 wt.% of aromatic compounds and 17 wt.% of aliphatic compounds, a flash point within a range of 45 to 90 °C, and more preferably close to 70 °C.

[0100] Application Examples 1

[0101] The pyrolytic oil obtained from tire pyrolysis, whose properties are described in Table 1, was used as a collecting agent in the flotation of copper and molybdenum minerals. Commercial diesel was used as a comparative collecting agent to that of the present invention. The copper and molybdenum content was estimated by X-ray fluorescence (XRF) using the Bruker S1 Titan instrument. The source ore came from a Chilean copper mine whose porphyry copper deposit contains head grades of 0.86 wt.% Cu and 0.03 wt.% Mo. The collecting reagent was added during the ore grinding process, which was carried out in a 5.4 L stainless steel Marcy laboratory ball mill with a standard ball collar. A solids content of 67 wt.% and 1 kg ore charges were used for approximately 11 minutes at 130 rpm to obtain a Pso of 150 µm.For the flotation process, the EDEMET laboratory flotation cell was used under the conditions detailed in Table 3. Flotation froth recoveries were made at times of 0, 1, 2, 4, 8, and 12 minutes. The material collected at each stage and the tailings were placed in an oven at 80 °C for 24 hours, after which the mass recovered at each stage and the tailings product were quantified. The copper and molybdenum content was also estimated for each sample.

[0102] Table 3 Edemet cell flotation parameters to estimate copper and molybdenum recovery, for comparison of TPO with Diesel.

[0103] Parameter Value Unit

[0104] Conditioning 30 s

[0105] Agitation conditioning 600 rpm

[0106] Float time 12 min

[0107] Agitation flotation 900 rpm

[0108] Paleo interval 10 s pH 10

[0109] MIBC 13 g tm- 1

[0110] buoyant agent

[0111] The copper and molybdenum recovery results for the rougher flotation process of the head ore are shown in Figures [Error! Reference source not found] and [Error! Reference source not found], respectively. It can be observed that both Diesel and TPO follow common flotation kinetic models for both copper and molybdenum, with similar cumulative recovery values. In the case of copper recovery, TPO shows a 6 percentage point improvement over Diesel in terms of cumulative copper, achieving a recovery of 78.7 wt.% copper. As for molybdenum, the recovery reaches a value of 39.7 wt.%, representing a 1% improvement. It is important to note that the use of picol oil (Tico) obtained from used tires generates a higher solids recovery in the flotation stage, reaching a maximum value of 10.7 wt.%, with copper and molybdenum concentrate grades similar to or lower than those obtained with diesel, as observed in Part B of the Error! Reference source not found, and Error! Reference source not found.

[0112] Application Example 2

[0113] The pyrolytic oil was subjected to oxidative desulfurization at 30°C (sample code: ODS-30) and 60°C (sample code: ODS-60) for 2 hours. The resulting phases were then separated, with the lighter fraction being of interest. In both cases, the lighter fraction was evaluated as a collecting agent in the flotation of copper and molybdenum minerals, the parameters of interest for which are detailed in Table 2. Commercial diesel was also used as a collecting agent for comparison with the one of the present invention. The copper and molybdenum content was estimated by X-ray fluorescence (XRF) using the Bruker S1 Titan instrument. The source ore comes from a Chilean copper mine whose porphyry deposit has head grades of 0.86 wt.% Cu and 0.04 wt.% Molybdenum. % of Mo. The collector reagent was added in the ore grinding process, which was carried out in a 5-inch Marcy laboratory ball mill.A 4 L stainless steel flotation cell with a standard ball collar was used, in which a solids percentage of 67 wt. % and 1 kg of ore were charged, for an approximate time of 11 minutes at 130 rpm to obtain a Pso of 150 pm. For the flotation process, the EDEMET laboratory flotation cell was used under the conditions detailed in Table 3, as in application example 1. Flotation froth recoveries were made at times of 0, 1, 2, 4, 8 and 12 minutes.

[0114] The material collected in each stage and the tailings were placed in an oven at 80 °C for 24 hours, after which the mass recovered in each stage and the tailings product were quantified. The copper and molybdenum grades were estimated for each sample. The flotation cell recovery results for copper and molybdenum are shown in Figures [Error! Reference source not found] and [Error! Reference source not found], respectively. It can be observed that for both copper and molybdenum, there is a higher recovery compared to diesel. Oxidative desulfurization at both 30 °C and 60 °C leads to a substantial improvement in the amount of copper accumulated in the concentrate, reaching recoveries of up to 79.0 wt.% of the copper present in the ore, which represents a 4 percentage point improvement over the performance of diesel for the head ore used.Furthermore, an increase in the selectivity of copper minerals can be observed when using refined pyrolytic oil, as the copper grade increases in both cases with similar percentages of recovered material compared to diesel.

[0115] Regarding molybdenum, recovery increases significantly due to the combination of long-chain aromatic and aliphatic compounds, as described in the state-of-the-art review. In fact, ODS-30 flotation exhibits a substantial increase in molybdenum recovery, achieving a cumulative recovery of 42.9 wt.%, which represents 14.4 percentage points above the performance of diesel.

[0116] The application examples shown above are illustrative, serving to demonstrate the advantages of the invention. In this context, the appended claims are intended to claim the invention as broadly as possible, as conceived, and the examples presented are illustrative of applications selected from a multitude of all possible embodiments. It is also anticipated that advances in science and technology will make possible equivalents and / or substitutes not currently contemplated, and these variations should also be interpreted, where possible, as covered by the appended claims.

Claims

Claims 1. A collector reagent for use in the flotation of metal sulfide minerals, comprising a chemical composition with an aromatic compound content greater than 65 wt.% and aliphatic compound content less than 20 wt.%, with a flash point between 50 and 90 °C, wherein said product is obtained from a refining of tire pyrolysis oil, including: a) A thermal conversion of tires, involving a heating rate between 2 and 10 °C min -1 , to reach a final temperature between 350 - 550 °C, and a pressure range between 1 to 10 bar, from which a tire pyrolysis oil is obtained; and b) A treatment of the pyrolysis oil obtained from the thermal conversion of tires, by adding an oxidizing agent, in a temperature range between 20 and 80°C.

2. The collector reagent described in claim 1, comprising the use of new, used or out-of-use passenger origin (PCR) tires or new, used or out-of-use off-road type (OTR) tires, or a mixture of the above.

3. The collector reagent described in claim 1, comprising the generation of an inert atmosphere for the thermal conversion of tires, including, but not limited to, atmospheres of nitrogen, helium, argon, carbon dioxide, water, decomposition gases from the tires themselves, or another source with a low oxygen level.

4. The collector reagent described in claim 1, comprising the use of oxidizing agents for the oxidative desulfurization of the pyrolysis oil, including, but not limited to, sulfuric acid, hydrogen peroxide, sodium, potassium or other perchlorates, organic acids such as formic acid, acetic acid, tert-butyl acid, or inorganic acids such as sulfuric acid, nitric acid, phosphoric acid, or a mixture thereof.

5. The collector reagent described in claim 4, comprising a ratio between 1:100 wt. and 20:100 wt. of oxidizing agent and pyrolysis oil, respectively.

6. The collector reagent described in claim 4, comprising the separation of the phases of the pyrolytic oil due to the oxidation process, using polar solvents including, but not limited to, acetone, carbon disulfide, methanol, ethanol, propylene glycol, ethylene glycol, acetonithlo, water, or a combination thereof.

7. The collector reagent described in claim 6, wherein the phase separation comprises a solvent extraction process carried out at a temperature between 20 and 60°C and a pressure between 1 and 10 bar.

8. The collector reagent described in claim 6, wherein the phase separation is achieved by decantation processes, cocurrent extraction processes, countercurrent extraction processes, or other polarity-based phase separation processes.

9. The collector reagent described in claim 1, comprising a carbon content between 78.2 and 86.6 wt.%, hydrogen between 10.3 and 12.4 wt.%, oxygen between 2.1 and 6.8 wt.%, and sulfur less than 1.6 wt.%.

10. The collector reagent described in claim 1, comprising a concentration of aromatic compounds of at least 65 wt. %, in which are included all types of aromatic compounds, whether monocyclic, heterocyclic, polycyclic and / or substituted by functional groups containing carbon, oxygen, hydrogen and / or sulfur, or a combination thereof.

11. The collector reagent described in claim 1, comprising a concentration of less than 20 wt. % of photic compounds with a carbon chain of between 7 and 18 atoms, which may contain functional groups composed of carbon, oxygen, hydrogen and / or sulfur, or a combination thereof.

12. The collector reagent described in claim 1, comprising a ratio of 1 to 300 g per tonne of ore treated in the flotation processes.

13. The collector reagent described in claim 1, further comprising a pH adjustment of the reagent.

14. The collector reagent described in claim 1, wherein the minerals of interest recovered in the flotation process contain chalcopyrite, pyrite and molybdenite, or a combination thereof.

15. The collector reagent described in claim 1, wherein the collector composition comprises the addition of water, a pH control agent, an agent stabilizer, a preservative, an emulsifying agent, the combination with other hydrocarbons or water-immiscible liquids, or a combination of these.

16. A method for obtaining a collector reagent for the flotation of metallic sulfide minerals, comprising the steps of: a) Carrying out a thermal conversion of tires, involving a heating rate between 2 and 10 °C min -1 , to reach a final temperature between 350 - 550 °C, and a pressure range between 1 to 10 bar, from which a tire pyrolysis oil is obtained; and b) Carry out a treatment of the pyrolysis oil obtained from the thermal conversion of tires, by adding an oxidizing agent, in a temperature range between 20 and 80°C, where a chemical composition is obtained with a percentage of aromatic compounds greater than 65 wt. %, and alpha-hydric compounds less than 20 wt. %, with a flash point between 50 and 90 °C.

17. The method described in claim 16, comprising the generation of an inert atmosphere for the thermal conversion of tires, including, but not limited to, atmospheres of nitrogen, helium, argon, carbon dioxide, water, decomposition gases from the tires themselves, or another source with a low oxygen level.

18. The method described in claim 16, comprising the use of oxidizing agents for the oxidative desulfurization of the pyrolysis oil, including, but not limited to, sulfuric acid, hydrogen peroxide, sodium, potassium or other perchlorates, organic acids such as formic acid, acetic acid, tert-butyl acid, or inorganic acids such as sulfuric acid, nitric acid, phosphoric acid, or a mixture thereof.

19. The method described in claim 16, comprising a ratio of 1:100 wt. and 20:100 wt. of oxidizing agent and pyrolysis oil, respectively.

20. The method described in claim 16, comprising the separation of the phases of the pyrolytic oil due to the oxidation process, using polar solvents including, but not limited to, acetone, carbon disulfide, methanol, ethanol, propylene glycol, ethylene glycol, acetonithlo, water, or a combination thereof.

21. The method described in claim 20, wherein the phase separation comprises a solvent extraction process carried out at a temperature between 20 and 60°C and a pressure between 1 and 10 bar.

22. The method described in claim 20, wherein the phase separation is achieved by decantation processes, co-current extraction processes, countercurrent or other polarity-based phase separation processes. 21

Images