PROCESS FOR OBTAINING ORE DUST SUPPRESSANT RESIN, ORES DUST SUPPRESSANT RESIN, PROCESS FOR INHIBITION OF ORE PARTICULATE EMISSION AND RESIN USE

Abstract

The proposed invention is a process for obtaining the ore dust suppressant resin with the chemical recycling of Poly thermoplastic polymer (Ethylene Terephthalate) or PET. It is proposed a method for obtaining the resin by using the depolymerization reaction methodology of the Poly polymer (Ethylene Terephthalate) obtained from post-consumption PET bottles, in the presence of cationic surfactant hexadeciltrimetrilamonio bromide (CTAB).

The resin is thus obtained being subsequently added to the same PVP K-90 (Polyvinylpyrrolidone) as increasing load on the final viscosity of the resin. Other additives such as lignin extracted from plants such as leaves and tree branches may also be added, in this case, incorporated to make the resin more hydrophobic.

Claims

1-17. (canceled)

18. Ore dust suppressant resin obtained by a process comprising: i) depolymerizing clean fragments of post-consumption polyethylene terephthalate polymer (PETpc) in the presence of hexadecyltrimethylammonium bromide (CTAB) and an alkaline medium to obtain a reaction medium; ii) neutralizing the reaction medium after completion of the depolymerization reaction and precipitation of the terephthalic acid monomer (TPA); iii) filtrating the remaining medium which comprises ethylene glycol and extracting excess salt with an alcoholic solvent to obtain a solution; iv) subjecting the solution in iii) to an evaporation process to remove excess water, thus obtaining an intermediate resin; v) adding a viscosity increasing agent to the intermediate resin obtained in iv), thereby obtaining an ore dust suppressant resin.

19. The ore dust suppressant resin of claim 18, wherein the process further comprises adding an agent to increase the hydrophobicity of the ore dust suppressant resin obtained in v).

20. The ore dust suppressant resin of claim 18, comprising functional groups in five absorption peaks in the infrared region (IV) of 3373, 1457, 1296, 1075 and 1037 cm1 respectively.

21. A process for inhibition of ore particulate emissions comprising applying the ore dust suppressant resin of claim 18 to an area susceptible to ore particulate emissions.

22. A method for ore dust suppression comprising applying the resin of claim 18 to an area susceptible to ore dust.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0030] FIG. 1 is a representation of chemical reactions of PETpc depolymerization occurring in the process object of the present invention, shown without the addition of CTAB (Reaction I) and with the addition of CTAB (Reaction II).

[0031] FIG. 2 illustrates the characterization of the PET resin by infrared spectroscopy in transmission mode.

[0032] FIG. 3 illustrates the thermogravimetric analysis (TGA) of the product, and the experiments conducted at a heating rate of 10 C..Math.min.sup.1, in an inert atmosphere of N.sub.2 and oxidant (synthetic air) at a temperature range of 30 to 450 C. FIG. 3(a) refers to TPA and FIG. 3(b) to PETpc.

[0033] FIG. 4 shows the DSC curves for samples of (a) PETpc and (b) TPA.

DETAILED DESCRIPTION OF THE INVENTION

[0034] For performing the present invention it is common that the post-consumption PET plastic (PETpc) is subjected to a preliminary process of recycling and cleaning before depolymerization reaction comprising i) selecting waste plastic composed of PETpc from selective collect; ii) removing portions of different materials to PETpc from waste plastics (for example, bottle top and bottom); iii) washing; iv) drying; v) grinding and standardization of fragment size.

[0035] After the cleaning process it is initiated the PETpc chemical recycling process itself, comprising the following steps: i) the depolymerization PETpc clean fragments in the presence of a cationic surfactant and an alkaline medium; ii) neutralization of the reaction medium after completion of the depolymerization reaction and precipitation of the terephthalic acid monomer (TPA); iii) filtration of the remaining medium containing ethylene glycol and extraction of complementary salt excess with alcoholic solvent; iv) subjection of the solution obtained in step iii) to an additional evaporation process to remove excess water, thus obtaining an intermediate resin; v) addition of a viscosity increasing agent to the intermediate resin obtained in step iv) obtaining a ore dust suppressant resin, and optionally vi) addition of an agent to increase the hydrophobicity of the ore dust suppressant resin obtained in step v).

[0036] The cationic surfactant used in step i) is preferably hexadecyltrimethylammonium bromide (CTAB).

[0037] The depolymerization reaction as described in step i) is carried out for 1 to 2 hours, while the temperature is maintained within a range of 90 to 110 C.

[0038] In the extraction of excess complement salt with alcoholic solvent of step iii) the extraction alcoholic solvent used can be any alcoholic solvent, being preferably selected from the group consisting of isopropyl alcohol, ethanol, and methanol, and being preferably the isopropyl alcohol. After its use, the alcohol solvent can be recovered by distillation and reused in another stage salt removal. There is no discarding of the alcohol solvent, and it can be reused more times, until it is completely consumed.

[0039] The viscosity increasing agent added in step v) is selected from the group consisting of pyrrolidones, being preferably polyvinylpyrrolidone.

[0040] The agent for increasing the hydrophobicity optionally added in step vi) is selected from the group consisting of lignin obtained from vegetable and polyethylene wax, preferably with the lignin obtained from leaves and branches of trees through extraction with 50% ethanol-water mixture. The more hydrophobic is the resin, more efficient it is for use in ores.

[0041] The resin product was characterized, in structural terms, as described below.

[0042] The characterization of PET resin by infrared spectroscopy was performed in a FTIR, FTLA 2000-102 (ABBBOMEM) spectrometer, in transmission mode. The analyzes were recorded with a resolution of 4 cm.sup.1 in a wavelength range of 4000 of the 500 cm.sup.1 and an average of 32 scans. The spectrum obtained is shown in FIG. 2, where it was observed that the resin comprises characteristic functional groups on the five absorption peaks 3373, 1457, 1296, 1075 and 1037 cm.sup.1 respectively.

[0043] The assignments of peaks are for axial deformation in the region of 3373 cm.sup.1 for the OH group; 1639 cm.sup.1 for the CO group; 1457 and 1296 and the ethylene glycol (EG) and 1075 for the (CO)O group, where differences are observed in the appearance of intense and broad absorption in the region of 3373 cm.sup.1. This spectrum shows the specificity of PET resin, where it was possible to observe the PET depolymerization products.

[0044] Thermogravimetric analysis (TGA) was performed on a Shimadzu TG-50 equipment, where 10 mg of sample were used for analysis, and the experiments were conducted at a heating rate of 10 C..Math.min.sup.1, in an inert atmosphere of N.sub.2 and oxidizing (synthetic air) at a temperature range of 30 to 450 C., shown in FIG. 3.

[0045] The Differential Scanning Calorimetry Analysis (DSC) was performed on a Q100 equipment (TA Instruments) controlled by Universal V4.7 software (TA Instruments). The data were obtained at heating and cooling rates of 10 C. per minute, with N.sub.2 flow of 50 mL.Math.min.sup.1 in the temperature range of 25 to 260 C., shown in FIG. 4.

[0046] These results show that FIG. 3(a,b) has a thermal decomposition range in the range of 250 to 350 C. However, the PETpc had greater thermal stability in the range of 310 to 600 C. in oxidizing atmosphere and of 370 to 500 C. in an inert atmosphere. The first mass loss is due to the presence of co-monomers such as diethylene glycol (DEG). The second mass loss is the presence of EG in the carbon chain of PETpc.

[0047] The results of DSC calorimetry, FIG. 4 represents the cooling and heating curves for PETpc and TPA respectively.

[0048] The resin obtained was originated from PET pc and thus on its composition produced TPA after depolymerization reaction, where the cooling curve does not show a defined crystallization peak (T.sub.c), so the material has a slow crystallization kinetic, justifying its high molecular mass and the presence of copolymers that retard the crystallization process (the property that provides the desired transparency to PET during processing by injection-blow), FIG. 4(a). The crystallization of PETpc is only completed when the second heating curve is performed, and it is observed a T.sub.c=158 C., FIG. 4(a). The second heating curve showed a glass transition temperature, T.sub.g=81 C. and the melting temperature, T.sub.m=247 C. for PET.sub.pc in accordance with the work published by Prof. group De Paoli (Spinace, M. A.; De Paoli, M-A., J. Appl. Polym. Sci, 78, p. 20 (2001)). On the other hand, in FIG. 4(b), there was a peak of Tc=190 C. and Tm=225 C. which are typical for samples of TPA recovered from depolymerization of PETpc and present products of the resin preparation.

[0049] Pour point of he resin was also determined, by the manual method, in which the determined value of the pour point for the PET-UFES resin was 22 C., and this shows that the PET resin shows a good stability in critical conditions of low temperatures.

[0050] In a preferred embodiment, the depolymerization reaction described in step i) of the process of the present invention is carried out in an alkaline medium (NaOH 7.5 mol/L) at a temperature of 100 C. in a stainless steel reactor under temperature, pressure, time and pH control.

[0051] The following examples are presented for better understanding of preferred embodiments of the present invention, which are not limiting the scope thereof.

EXAMPLE 1

[0052] PETpc depolymerization reaction in the presence of CTAB surfactant. The depolymerization reaction is carried out using PETpc previously cleaned with water and detergent and dry, then ground into a size of 1 cm1 cm. The PETpc fragments are added to a flat bottom flask with three joints with a capacity of 1000 mL, in the presence of 650 mL of sodium hydroxide solution (NaOH) at a concentration of 7.5 mol/L in the presence of 160 mL of cationic surfactant CTAB, kept under constant stirring for 60 minutes at 100 C.

[0053] After 60 min of the depolymerization reaction it was added concentrated hydrochloric acid to neutralize NaOH and precipitation of the monomer terephthalic acid (TPA) with sodium chloride salt (NaCl), which are removed by filtration. The remaining medium containing ethylene glycol, is filtered under vacuum and isopropyl alcohol is added to remove excess sodium chloride salt (NaCl). The solution obtained is again subjected to an evaporation process at 100 C. for removal of excess water, obtaining 200 mL of the intermediate resin.

EXAMPLE 2

Preparation of Dust Suppressant Resin

[0054] At 200 mL of the intermediate resin obtained as described in Example 2 it was added 10 g of the product PVP K-90 (polyvinylpyrrolidone) in order to increase the final viscosity, obtaining the ore dust suppressant resin with a density of d=1.17 g/mL and viscosity of =55.6 mm.sup.2/s or 55.6 cSt.

[0055] The results presented in Examples 1 and 2 demonstrate the relevance and inventiveness of the present invention when demonstrating that the presence of the cationic surfactant in the reaction medium allows the reaction to obtain the intermediate resin is carried out at a much lower time (2 h according to Example 1) compared to the reaction time of the reaction without the presence of cationic surfactant (average time of 6 hours, according to the state of the art). Besides the significant reduction in reaction time it is emphasized that high purity products are obtained by the process of the present invention. FIG. 1 shows the schemes of the chemical reactions of PETpc depolymerization, with or without the use of CTAB surfactant as catalyst.

[0056] Alternatively, also as part of the invention, to the ore dust suppressant resin may be added other components to make the resin more hydrophobic. As example of an additive, but without limiting the understanding of the scope of the present invention, plant lignin can be added (such as leaves and tree branches) obtained by extraction with a mixture of 50% ethyl alcohol and 50% distilled water.

[0057] Having the present invention been described in the form of its preferred embodiments and examples, it should be understood that other possible variations are covered by the scope of the present invention, which is limited only by the contents of their claims, including possible equivalent modifications.