Method for recovering high-quality polyether polyol from refined polyether waste residues

Abstract

The invention discloses a method for recovering high-quality polyether polyol from refined polyether waste residues, which comprises the following steps: adding process water into the waste residues to separate polyether polyol from the waste residues, adding a metal capturing agent into the separated polyether polyol to blend, complexing the metal capturing agent and potassium ions in the blending process to form floccules, and separating the floccules from the waste residues to obtain the high-quality polyether polyol. After blending is completed, the materials are subjected to standing and layering, a polyether product layer is collected and subjected to dehydration treatment, and high-quality polyether polyol is obtained and is low in acid value and potassium ion content and light in product color.

Description

Technical Field

[0001] The invention belongs to the field of chemical industry and relates to a method for recovering high-quality polyether polyol from refined polyether waste residue. Background Art

[0002] Polyether is obtained by polymerization reaction of active hydrogen-containing compounds with ethylene oxide, propylene oxide, etc. under the action of catalysts. When potassium hydroxide is used as a catalyst, crude polyether is generated after the polymerization reaction is completed. The potassium ions remaining in the crude polyether are removed through a refining process (the potassium ion content in the product is generally ≤30ppm) before it can be used normally. The traditional polyether refining process is to add soft water and phosphoric acid to the crude polyether, stir and neutralize it at a certain temperature, add magnesium silicate, stir for a period of time, dehydrate and filter, and after the potassium ion content is less than the specified value, discharge the material to obtain qualified polyether and filter residue. These filter residues contain 20-35% polyether polyol, 40-55% potassium dihydrogen phosphate, and 15-25% magnesium silicate. If it is discharged directly, it will not only seriously pollute the environment, but also cause a huge waste of resources.

[0003] The current treatment method is to add the filter residue to the treatment kettle, add water or ethanol, stir and stand at a certain temperature, the upper layer is liquid phase and the lower layer is solid phase. After the upper liquid phase is taken out, it is dehydrated to obtain a polyether product, which has a darker color, a high acid value, and a very high potassium ion content. It affects the foaming performance when used in combined polyether polyols, and can only be treated as inferior polyether, which is not economical.

[0004] Sodium fumarate is a DTC broad-spectrum heavy metal precipitation / chelating agent. Sodium fumarate reacts with heavy metal ions to form water-insoluble chelated salts and precipitate. Sodium fumarate can react with a variety of heavy metal ions (such as chromium, nickel, copper, zinc, manganese, potassium, cadmium, vanadium, tin) at room temperature to form water-insoluble chelated salts and precipitate, thereby achieving the purpose of removing heavy metal ions. This reaction can be carried out at room temperature, and the drug cost is low, which is suitable for use in the presence of multiple heavy metal ions.

[0005] Trimercaptotriazine sodium salt can chelate with various heavy metal ions (copper, nickel, chromium, lead, cadmium, potassium, etc.) to form organic sulfide products that are insoluble in water and have good chemical stability. Trimercaptotriazine trisodium salt is effective in a wide range of pH values ​​and can be used to treat acidic and alkaline wastewater. Regardless of the concentration of heavy metal ions in the wastewater, it can achieve the removal effect. When multiple metal ions coexist, they can also be removed at the same time; when heavy metal ions exist in the form of complex salts (EDTA, tetramine, etc.), they cannot be completely removed by hydroxide precipitation method, and trimercaptotriazine trisodium salt can play a good removal role. Trimercaptotriazine trisodium salt is not affected by coexisting salts in the wastewater when precipitating heavy metals. Summary of the invention

[0006] To solve the above problems, the present invention provides a method for recovering polyether polyols from refined polyether waste residues. The polyether recovered by the method has good quality, low acid value and potassium ion, and light color.

[0007] In order to achieve the purpose of solving the above technical problems, the present invention adopts the following technical solutions:

[0008] The invention discloses a method for recovering high-quality polyether polyol from refined polyether waste residue, which is characterized in that it comprises the following steps: adding process water to the refined polyether waste residue to separate the polyether polyol, adding a metal scavenger to the separated polyether polyol for potassium ion complexation, then allowing the blend to stand and separate, collecting the polyether polyol product for dehydration treatment, and obtaining the target product, high-quality polyether polyol.

[0009] Furthermore, the process of the method for recovering high-quality polyether polyols of the present invention can be as follows: the volume ratio of refined polyether waste residue to process water is 1:0.5~1, the process water temperature is 15~80°C, the metal capture agent is 0.2~0.8 times the potassium ion concentration, the mixed solution is allowed to stand and layered, and then the polyether polyol material is collected for dehydration treatment to obtain the target product, high-quality polyether polyol.

[0010] Furthermore, in the method for recovering high-quality polyether polyols of the present invention, mechanical stirring is required when the process water is used to purify the polyether waste residue, and the stirring time is 10 minutes to 120 minutes. The waste residue liquid needs to be treated by a centrifuge and the centrifuge liquid is collected.

[0011] Furthermore, in the method for recovering high-quality polyether polyols of the present invention, the mass fraction of the metal scavenger is 1% to 20%, and the material temperature during the complex reaction is 20° C. to 50° C.

[0012] Furthermore, in the method for recovering high-quality polyether polyols of the present invention, the polyether polyols collected after the complexed materials are allowed to stand and layered need to be dehydrated at a temperature of 100 to 120° C. and a pressure of -0.095 MPa to -0.098 MPa.

[0013] By adopting the above technical solution, the present invention has the following beneficial effects:

[0014] Compared with the traditional method, the polyether polyol recovered by the present invention has good quality, low acid value and potassium ion, light color, no influence on product quality and foaming activity during the use of the prepared combined polyether.

Claims

1. A method for recovering high-quality polyether polyols from refined polyether waste residues, comprising adding process water to the refined polyether waste residues to separate polyether polyols, adding a metal scavenger to the separated polyether polyols for potassium ion complexation, then allowing the blend to stand and separate, collecting the polyether polyol products for dehydration treatment, and obtaining high-quality polyether polyols.

2. According to claim 1, process water is added to the refined polyether waste to separate the polyether polyol, wherein the process water temperature is 15~80°C, and the mixture is mixed under mechanical stirring for 10min~120min, and the mixed material is transported to a centrifuge for solid-liquid separation, and the centrifuge liquid is collected.

3. According to claim 1, a metal scavenger is added to the separated polyether polyol to carry out potassium ion complexation, wherein the metal scavenger comprises: One or more of sodium thiocyanate, trisodium thiocyanate, sodium trimercaptotriazine, and dithiocarbamate derivatives.

4. according to claim 3, wherein the concentration of sodium thiocarbamate is 1% to 20%, the concentration of trisodium thiocyanate is 1% to 15%, the concentration of sodium trimercaptotriazine is 1% to 15%, and the concentration of dithiocarbamate derivatives is 1% to 20%.

5. According to claim 3, the metal scavenger is added to the polyether polyol for potassium ion complexation reaction at a temperature of 20-50°C, and mechanical blending is performed at the same time. After the blending is completed, the polyether polyol product layer is collected after standing for 30 minutes.

6. According to claim 1, the polyether polyol product is dehydrated at a temperature of 100-120°C and a pressure of -0.095Mpa--0.098Mpa.