Method for separation of oxide fillers from waste polymer composite materials
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-04-12
- Publication Date
- 2026-08-13
Abstract
Description
[0001] METHOD FOR SEPARATION OF OXIDE FILLERS FROM WASTE POLYMER COMPOSITE MATERIALS
[0002] TECHNICAL FIELD
[0003] The invention refers to a method for separating oxide fillers from waste polymer composite materials, in particular rubber and polyolefin, for the purpose of recycling and reuse.
[0004] PRIOR ART
[0005] Document US2020010765 Al discloses a method for processing rubber waste, in which the waste is chopped, undergo pre-treatment by blowing it with water vapor to a temperature of 100°C, subsequent thermal decomposition in a furnace, separation of the decomposition products into a vapor-gas mixture and a solid residue, and separation of the heavy hydrocarbon fraction from the vapor-gas mixture. Thermal decomposition is carried out at a temperature of 300-500°C, and when separating the mixture, the liquid hydrocarbons from the condensate are used as fuel, and the metal is extracted from the solid residue by magnetic and dielectric separation to obtain a product containing zinc oxide.
[0006] Another document CN115558796A discloses a method for extracting zinc oxide from waste tires combined with blast furnace ash resources, which includes the following steps: shredding of waste tires and magnetic separation of metal components; pyrolysis; pyrolysis gas and pyrolysis oil are used as heat sources for subsequent reduction and oxidation reactions; the pyrolysis solid substance is mixed with blast furnace ash containing zinc and a reduction reaction is carried out in an oxygen-deficient atmosphere to obtain solid waste and zinc-containing air flow, with the reduction reaction temperature being 1100~1300°C; separation of the solid, subsequent oxidation reaction where zinc is oxidized to zinc oxide, cooling and separation of the gas from a solid substance to obtain zinc oxide particles.TECHNICAL ESSENCE OF THE INVENTION
[0007] It is known to date to separate oxide fillers from waste polymer composite materials, in particular rubber and polyolefin materials, separately from rubber or polyolefin mixtures. The oxide fillers obtained from the individual mixtures are either only silicon dioxide or only titanium dioxide or only zinc oxide. There are no known methods for simultaneously separating silicon dioxide, titanium dioxide, and zinc oxide from waste polymer composites while preserving the physicochemical properties and chemical composition of the resulting oxide fillers.
[0008] The task and purpose of the invention is to create a method for simultaneously separating from a mixture of waste polymer materials, which are rubber and polyolefin, oxide fillers that are silicon dioxide and titanium dioxide and zinc oxide, at the same time. The method is supposed to ensure a yield of not less than 80 to 90% of the oxide fillers used in them and guarantee the preservation of the physicochemical properties and chemical composition of the obtained oxide fillers, which should enable their recycling and reuse for the production of polymer composite materials.
[0009] The invention task is solved via a method that entails the following:
[0010] First stage dry shredding, which runs in parallel with a separate installation for waste rubber mixtures and a separate installation for waste polyolefin mixtures
[0011] Second stage when the resulting shredded rubber mixtures and shredded polyolefin mixtures are mixed and undergo thermal treatment and
[0012] Third stage - the oxide fillers are separated from the resulting oxide mixture.
[0013] In accordance with the invention, the method includes the following sequence of technological operations:
[0014] First stage, waste polymer composite materials, rubber mixtures and polyolefin mixtures undergo parallel processing including dry shredding, the rubber mixtures are shredded in a shredder unit for crushing and recycling, followed by a screening process in which particles with a size of 50 mm are separated, and those with a size of 5 mm are removed from the technological process. The polyolefin mixtures undergo dry shredding to a particle size of 70mm, followed by washing to remove liquid and powder impurities and filtration of the washed polyolefins and separation ofwaste filter water, which after purification is reused, as the dehydrated material is dried with hot air at a temperature of up to 70°C.
[0015] Second stage in which the shredded mixtures from the First stage are fed simultaneously into the aggregate and mixed, and the thermal treatment process begins, which proceeds through several stages of sequential heating and they are:
[0016] Stage A- The shredded mixture undergo indirect heating in a steel crucible, by externally located resistance electric heaters or by burning natural gas and drying, with stirring using a rotary stirrer at a speed of 5-10 revolutions per minute at a temperature of 95°C in a non-pressurized volume, the heating occurs at a rate of 3-5°C per minute for 25-30 minutes with limited diffusion access of air and removal of the formed gaseous products, water vapor through a gas outlet hole in the crucible lid;
[0017] Stage B - The heating of the mixture occurs at a rate of 5-10 revolutions per minute at a temperature of 250 C, a process of decomposition and evaporation of hydrocarbon components takes place for a time of 30 to 40 min, followed by diffusion penetration of air and partial oxidation of the volatile hydrocarbons formed with limited access to air at a partial pressure of oxygen from 0.5 to 5%;
[0018] Stage C-The heating of the working volume is up to 500°C at a rate of 10-15°C per minute for 20 minutes with unlimited diffusion access to air and processes of evaporation and oxidation of volatile and part of non-volatile hydrocarbons occur for 30-40 minutes;
[0019] Stage D- a process of maintaining a constant temperature of 650°C takes place for 40-50 min with air blowing;
[0020] Stage E - the temperature is increased to 670°C and maintained constant for 30-40 minutes with air blowing;
[0021] Stage F - The resulting oxide mixture is cooled to 250°C for 30-40 min in the working space of the heat unit with cold air blowing, after which the oxide mixture is unloaded into a steel container, where it is convectively cooled to a temperature below 100°C.
[0022] Third stage of separation of the obtained oxide fillers from the obtained oxide mixture, the separation being magnetic and subsequent dielectric separation to separate the oxide fillers or ananalytical method, the obtained oxide fillers being silicon dioxide, titanium dioxide and zinc oxide.
[0023] According to the invention, waste rubber mixtures are from end-of-life automobile tires, in particular light tires, and polyolefin mixtures are from high-pressure polyethylene and / or low-pressure polyethylene and / or polypropylene.
[0024] The amount of separated oxide fillers per 100 w / w of the oxide mixture obtained after the thermal treatment is / in w / w / zinc oxide in an amount of 3.5 to 4, silicon dioxide from 40 to 60 and titanium dioxide from 10 to 15.
[0025] Ensuring the necessary oxidation potential in the working volume during the individual periods of thermal treatment is carried out by adjusting the corresponding openings in the roof of the heat unit in which the process is carried out. The heat unit is a steel crucible with a steel lid, in which there are technological openings for gas removal and for supplying oxidizing air.
[0026] To remove solid phase carbon residue impurities from the oxide material, dry gravity separation of the solid carbon residue particles is performed.
[0027] The advantages provided by the method for separating oxide fillers from waste polymer composite materials according to the invention are:
[0028] The method guarantees the separation of oxide fillers from waste tires and waste polyolefin materials at the same technological site;
[0029] By the method, three oxide fillers are separated: zinc oxide, silicon dioxide, and titanium dioxide.
[0030] The oxide fillers separated by the method are in accordance with the requirements for their reuse, which is achieved with the created technological regime and sequence of technological operations.
[0031] EXAMPLES OF THE INVENTION IMPLEMENTATION
[0032] The invention is illustrated by the following examples, which do not limit it.
[0033] Waste polymer composite materials containing oxide fillers are separated and stored as two separate raw material sources upon receipt at the work site, being the two separate raw materialsources: end-of-life tires containing oxide filler, such as tires being so-called green tires, light tires, and polyolefin materials being end-of-life and being high-pressure polyethylene and / or low-pressure polyethylene and / or polypropylene.
[0034] Example 1.
[0035] First stage
[0036] Waste polymer composite materials, rubber and polyolefin, undergo parallel shredding.
[0037] The waste rubber materials undergo dry shredding, which is carried out in a specialized shredder unit for crushing and recycling of solid polymer materials PROSING type, in which the technical possibility is provided for changing the distance between the cutting elements and the limiting surfaces of the shredder of waste automobile tires with oxide filler of rubber mixtures, followed by screening of the shredded material with a maximum particle size of 50 mm. Two fractions are obtained: a fraction with a particle size from 5mm to 50mm. The fraction with a minimum particle size of up to 5 mm is removed from the technological process due to the insignificant content of oxide filler in it (less than 5%), while the coarse fraction containing up to 40% oxide filler undergoes thermal treatment under a corresponding physicochemical regime in the volume of the treated material.
[0038] Waste polyolefins are processed in parallel with waste rubber materials in a separate plant. Waste polyolefin materials with oxide filler, which are pre-sorted after the end of their life cycle, and after dry shredding to a maximum particle size of 70mm, the resulting material is washed to remove liquid and powder impurities with a maximum particle size of 1mm, in which the wastewater is purified and recycled for reuse, and the solid phase sediment of impurities is recycled or disposed of. After filtering the washed polyolefin material with oxide filler and separating waste filter water, which is reused after purification, the dehydrated material is dried with hot air at a temperature of up to 70°C. The dried polyolefin material, after dry centrifugation and additional removal of residual waste polymer impurities, which are recycled or disposed of, is fed for thermal treatment under a corresponding physicochemical regime in the volume of the thermal treatment unit and, respectively, in the volume of the treated polyolefin material with oxide filler.Second stage - thermal treatment.
[0039] The thermal treatment of the mixture obtained in the first stage goes through the following technological stages:
[0040] -Heating stage A: indirect heating in a steel crucible using externally located resistance electric heaters or by burning natural gas and drying the shredded mixture in a bulk bed and stirring with a slow rotating stirrer 5 rpm (revolutions per minute) at a temperature of 95 °C in an unpressurized volume, heating at a rate of 3° per minute for 25 min with limited diffusion access of air as well as the possibility of removing the formed gaseous products. Water vapor and the gases released at high temperatures are removed from the unpressurized crucible through a gas outlet hole in the crucible lid / gas mainly (water vapor);
[0041] Stage B of heating at a rate of 5° per minute of the mixture in the working volume at 250° C, during which decomposition and evaporation of hydrocarbon components occur for 30 min, followed by diffusion penetration of air and partial oxidation of the volatile hydrocarbons formed with limited access to air such that the maximum partial pressure of oxygen in the working space is 0.5%, / i.e. in a weakly oxidizing environment / ;
[0042] Stage C of heating the working volume to 500° C at a rate of 10° degrees per minute for 20 minutes with unlimited diffusion access of air in the working space and a correspondingly higher oxidation potential, during which the processes of evaporation and oxidation of the volatile and part of the non-volatile hydrocarbons in the volume of the material layer are completed in 30 minutes;
[0043] Stage D a process of maintaining a constant temperature in the working volume of 650°C for 40min and blowing air into the residual material layer, which ensures a high oxidation potential in the volume of the bulk material for the most complete oxidation of the organic mass of the composite and obtaining residual oxide material containing impurities of unbumed solid phase carbon;
[0044] Stage E increasing the temperature, which is maintained constant in the working volume of 670°C for 30 min, after which air is blown into the residual material layer, which ensures a high oxidation potential in the volume of the bulk material for the most complete oxidation of theorganic mass of the composite and the production of residual oxide material containing impurities of unbumed solid phase carbon.
[0045] Stage F The oxide mixture is cooled to 250°C for 30 min in the working space of the heat unit by blowing cold air into its volume, after which the product is unloaded into a steel container, where it is convectively cooled to a temperature lower than 100°C.
[0046] The third stage is the separation of the obtained oxide fillers from the oxide mixture obtained after thermal treatment by magnetic and subsequent dielectric separation to separate the oxide fillers based on their dielectric properties and the obtained oxide fillers. 100 w / w of the obtained oxide mixture are in the following quantities: zinc oxide in quantity is 3.5, silicon dioxide is 40 and titanium dioxide is 10.
[0047] Example 2
[0048] First stage
[0049] Waste rubber materials undergo dry shredding, which is carried out in a specialized shredder unit for crushing and recycling of solid polymer materials, PROSING type, which provides a technical possibility to change the distance between the cutting elements and the limiting surfaces of the waste tire shredder. The shredded material is then sieved with a maximum particle size of 50 mm. Two fractions are obtained: a fraction with a particle size of 5 mm to 50 mm and a fraction with a maximum particle size of up to 5 mm. The smaller fraction of shredded tires is removed from the technological process due to the insignificant content of oxide filler in it (less than 5% of the mass of the polymer material), while the coarse fraction containing over 40% oxide filler undergoes thermal treatment under a corresponding physicochemical regime in the volume of the treated material.
[0050] In parallel, the waste polyolefin materials with oxide filler undergo dry shredding to a maximum particle size of 70mm, after which the resulting material is washed to remove liquid and powder impurities with a maximum particle size of 1mm, in which case the wastewater is purified and recycled for reuse, and the solid phase sediment of impurities is recycled or disposed of. After filtering the washed polyolefin material with oxide filler and separating waste filter water, which is reused after purification, the dehydrated material is dried with hot air at a temperature of up to 70°C. The dried polyolefin material, after dry centrifugation and additional removal of residualwaste polymer impurities, which are recycled or disposed of, is fed for thermal treatment under a corresponding physicochemical regime in the volume of the thermal treatment unit and, respectively, in the volume of the treated polyolefin material with oxide filler.
[0051] Second stage - heat treatment.
[0052] The heat treatment of the mixture obtained in the first stage from automobile tires with oxide filler and polyolefin materials with oxide fillers goes through the following stages:
[0053] -Stage A heating / indirect heating in a steel crucible using externally located resistance electric heaters or by burning natural gas / and drying of the shredded mixture in a loose layer and stirring with a slow rotating stirrer 10 rpm. at a temperature of 95° C in an unpressurized volume heating at a speed of 5° per minute for 30 minutes with limited diffusion access of air as well as the possibility of removing the formed gaseous products. Water vapor and the gases released at high temperatures are removed from the unpressurized crucible through a gas outlet hole in the crucible lid / gas mainly (water vapor);
[0054] - Stage B heating at a rate of 10° degrees per minute of the mixture in the working volume at 250° C, during which decomposition and evaporation of hydrocarbon components occur for 40 min, followed by diffusion penetration of air and partial oxidation of the volatile hydrocarbons formed with limited access to air, with the maximum partial pressure of oxygen in the working space being 5%, / i.e. in a weakly oxidizing environment / ;
[0055] -Stage C: heating the working volume to 500°C at a rate of 15°C / min for 20 min with unlimited diffusion access of air into the working space and a correspondingly higher oxidation potential, whereby the processes of evaporation and oxidation of the volatile and part of the non-volatile hydrocarbons in the volume of the material layer are completed in 40 min;
[0056] -Stage D is a process of maintaining a constant temperature in the working volume of 650°C for 50 min and blowing air into the residual material layer, which ensures a high oxidation potential in the volume of the bulk material for the most complete oxidation of the organic mass of the composite and obtaining residual oxide material containing impurities of unbumed solid phase carbon;-Stage E, increasing the temperature, which is maintained constant in the working volume at 670°C for 40 minutes, after which air is blown into the residual material layer, which ensures a high oxidation potential in the volume of the bulk material for the most complete oxidation of the organic mass of the composite and obtaining residual oxide material containing impurities of unbumed solid phase carbon.
[0057] -Stage F the oxide mixture is cooled to 250°C for 40 min in the working space of the heat unit by blowing cold air into its volume, after which the product is unloaded into a steel container, where it is convectively cooled to a temperature lower than 100°C.
[0058] Third stage - separation of the resulting oxide fillers from the oxide mixture obtained after the thermal treatment by an analytical method, which includes:
[0059] A finely ground sample of 0.5 - 1 g is weighed. A 10-fold excess of the flux (KNaCO₃) is measured. 2 / 3 of the measured amount of melter is separated to carry out a “dry wash”. A special feature of loading the platinum crucible is the requirement that the sample is not in direct contact with its walls. A portion of the melter is poured into it in advance. A dimple is carved into the fill, into which the sample mixed with the flux is placed. It is covered with the rest of the melter. Place a lid on the crucible and place it in a cold muffle furnace. The temperature gradually rises to 10000C. Heating continues for 30 minutes, during which the mixture is completely melted and the release of CO₂ bubbles ceases. The crucible is cooled in air until its red color disappears, 1 / 3 of its capacity is filled with distilled water and heated moderately, without allowing it to boil. The alloy (melt) is transferred to a beaker, 20 ml of concentrated HC1 and 10 ml of a 1% freshly prepared and heated to 70-80C gelatin solution are added. The solution contents are evaporated on a water bath to dryness. The dry residue is treated twice with HC1 concentration. The latter method is used: 5 ml of concentrated HC1 are added, after which the solution is evaporated to dryness. This aims to completely convert the resulting colloidal silicic acid into the precipitable gel form. The dry residue is poured again with 5 ml of concentrated HC1. After 10 min. 100 ml of hot water are added. The resulting patchy silicic acid precipitate is filtered hot through a “white ribbon” filter. The precipitate is washed with hot 2% hydrochloric acid and then with hot water to prevent its peptization, until a negative reaction for chloride ions (AgNC sample).The filter with the silicic acid precipitate (precipitated form) is dried, carbonized and the precipitate is calcined at 10000 C for 40 min. The weight form is SiO₂.
[0060] After filtration, the filtrate containing TiO₂ and ZnO₂ is precipitated with ammonia (NHs). The precipitate of Ti(OH)₄ is amorphous and has strongly pronounced absorption properties. This requires precipitation to be carried out from more concentrated solutions and to be filtered immediately while hot. The precipitate is washed to remove chloride ions with a hot solution of ammonium nitrate, neutralized with NH₃ (pH=5-6).
[0061] Upon addition of NH₃, a white precipitate of Zn(OH)₂ is formed, but the precipitation is incomplete. In the presence of ammonium salts (when washing the precipitate from Ti(OH)₄) no precipitate is formed. In excess ammonia, the precipitate dissolves due to complexation.
[0062] Potassium hexacyanoferrate (II) is used to separate ZnOz. White zinc hexacyanoferrate Zn2[Fe(CN)6] precipitates.
[0063] Zinc belongs to the third group of cations (subgroup II), with the group precipitant (NH₄)₂S, ZnS is obtained. Zinc sulfide has a small solubility product Ks=1,6.10⁻²⁴.
[0064] The obtained quantities of oxide fillers after the analytical method are zinc oxide in an amount of 4, silicon dioxide is 60 and titanium dioxide is 15 per 100 w / w. of the obtained oxide mixture after thermal treatment
Claims
PATENT CLAIMS1. A method for separating oxide fillers from waste rubber and polyolefin mixtures including dry shredding and thermal treatment, characterized in that the method includes, in the first stage, dry shredding, which takes place in parallel in a separate installation for the waste rubber mixtures and in a separate installation for the waste polyolefin mixtures, in the second stage, the obtained shredded rubber mixtures and shredded polyolefin mixtures are mixed and undergo thermal treatment, and in the third stage, in which the oxide fillers are separated from the obtained oxide mixture, the method including the following sequence of technological operations: in the first stage, waste polymer composite materials, rubber mixtures and polyolefin mixtures, undergo parallel processing including dry shredding, being the rubber mixtures shredded in a shredder unit for crushing and recycling, which is followed by a screening process, in which particles with a size of 50 mm are separated, and those with a size of 5 mm are removed from the technological process, the polyolefin mixtures undergo dry shredding to a particle size of 70 mm, which is followed by washing to remove liquid and powder impurities and filtration of the washed polyolefins and separation of waste filter water, which is reused after purification, as the dehydrated material is dried with hot air at a temperature of up to 70° C, which is followed by a second stage, in which the shredded mixtures from the first stage are simultaneously fed into the unit and mixed, and the thermal treatment process begins, which takes place in several stages and they are: stage A - the shredded mixture undergoes indirect heating in a steel crucible, by means of externally located resistance electric heaters or by burning natural gas and drying, with stirring using a rotary stirrer at a speed of 5-10 rpm at a temperature of 95°C in an unpressurized volume, heating at a speed of 3-5°C per minute for 25-30 minutes with limited diffusion access to air and removal of the formed gaseous products, water vapor through a gas outlet hole in the lid of the crucible, followed by stage B in which heating is at a speed of 5-10°C per minute of the mixture at a temperature of 250°C, a process of decomposition and evaporation of hydrocarbon components takes place for a time of 30 to 40 minutes, followed by diffusion penetration of air and partial oxidation of the volatile hydrocarbons formed with limited access to air at a partial pressure of oxygen from 0.5 to 5%, at stage C the heating of the working volume is up to 500°C at a rate of 10- 15 °C per minute for 20 minutes with unlimited diffusion access of air and processes of evaporation and oxidation of volatile and part of non-volatile hydrocarbons occur for 30-40 minutes; stage D follows in which a process of maintaining a constant temperature of650°C occurs for 40-50 minutes with air blowing; in stage E the temperature is increased to 670°C and maintained constant for 30-40 minutes with air blowing; in the next stage F the resulting oxide mixture is cooled to 250°C for 30-40 minutes, in the working space of the heat unit with cold air blowing, after which the oxide mixture is unloaded into a steel container, where it is convectively cooled to a temperature below 100°C; a third stage of separation of the obtained oxide fillers from the obtained oxide mixture follows, the separation being magnetic and subsequent dielectric separation for separation of the oxide fillers or an analytical method, the obtained oxide fillers being silicon dioxide, titanium dioxide and zinc oxide.
2. Method according to claim 1, characterized in that the waste rubber mixtures are from end-of-life tires, in particular light tires, and the polyolefin mixtures are from high-pressure polyethylene and / or low-pressure polyethylene and / or polypropylene.
3. Method according to claim 1, characterized in that the amount of the separated oxide fillers per 100 w / w of the oxide mixture obtained after the thermal treatment is / in parts per million / zinc oxide in an amount of 3.5 to 4, silicon dioxide from 40 to 60 and titanium dioxide from 10 to 15.