RU2138087C1 - Liquid organic waste recovery technique - Google Patents

Abstract

FIELD: recovery of liquid organic wastes by extraction technique. SUBSTANCE: liquid wastes containing organophosphorous compounds are mixed up with binder of group of alkaline-earth metal carbonates in proportion of 1: 3-5 mass parts, respectively, and subjected to heat treatment at 300- 350 C until mixture is fully cured. Degree of conversion obtained in the process is about 99,7%. EFFECT: facilitated procedure, reduced cost. 2 cl, 1 tbl

Description

 The present invention relates to the field of liquid organic waste processing technology according to the method of extragenic technology and can be used at enterprises of the chemical industry, the waste of which contains spent organic extractants and impurities of heavy metals.

 The urgency of the problem being solved consists in the need to extract traces of heavy metals from solutions of spent extractants, mainly organophosphorus, the presence of which is an inevitable consequence of the removal of toxic substances by traditional means, which prevents landfill in the soil in accordance with applicable environmental safety standards. This necessitates either their preliminary destruction or their transformation into safe products that are stable under natural storage conditions.

 A known method for the disposal of liquid waste containing impurities of toxic metals by evaporation at a temperature below the boiling point in combination with the supply of heating gas, followed by contact with a self-curing waterproof material. However, the known method is time-consuming and unacceptable for the case when the waste contains minor impurities of heavy metals and at the same time organophosphorus compounds that do not decompose under the conditions of the known method (patent N 563403, MKI G 21 F 9/00, publ. 05.07.97, therefore further disposal and disposal of waste is difficult.

 Known closest to the claimed technical essence of the method of disposal of liquid organic waste containing organophosphorus compounds, the patent of Germany N 23 56253, CL. IPC G 21 F 9/16, publ. 06/09/02, which consists in the thermal decomposition of their mixture with a binder and curing, while the organic waste in the form of oils or solvents is mixed with an organic binder from the group of polyethylene, polystyrene or polyvinyl chloride, or mixtures thereof, taken in the form of an aqueous suspension. At the same time, for 100 parts by weight a binder accounts for 30 to 40 parts by weight water, and the ratio of waste and hydraulic binder is in the range from 2: 1 to 3: 1 parts by weight respectively.

The disadvantages of this method include the difficulty of achieving the complete decomposition of tributyl phosphate (TBP) contained in the waste, because the processing temperature of the reaction mixture does not exceed 100-200 ^o C, which negatively affects the efficiency of extraction of heavy metals and ultimately reduces the quality and completeness of the recycling process.

 The technical problem to which the invention is directed is to develop a simple and affordable method for the disposal of liquid organic waste containing organophosphorus compounds, for example TBP, and minor impurities of toxic elements from the group of heavy metals in amounts not exceeding 4.0% wt. (505-510 mg / l), while the final disposal products must meet the requirements of environmental friendliness and safety and should be suitable for subsequent disposal in the soil.

 A new technical result achieved by using the proposed method is to simplify and reduce the complexity, increase the efficiency of extraction of toxic elements contained in liquid organic waste (the realized degree of conversion of the order of 99.7%), and reduce the volume and cost of the method by reducing the consumption of raw materials compared to the prototype.

The specified technical result is achieved by the fact that in the known method for the disposal of liquid organic waste containing an organophosphorus compound by thermal decomposition of their mixture with a binder, in accordance with the proposed method, the waste is fed to the reactor simultaneously with a binder from the group of alkaline earth metal carbonates in the form of natural minerals the mixture is subjected to heat treatment at a temperature in the range from the boiling point of the organophosphorus compound to 350 ^o C.

 An additional technical result is achieved by introducing magnesite, or calcite, or dolomite as a binder of a natural mineral per 100 wt. including organic waste take 300 - 500 parts by weight binder. The presence of essential features that are distinctive from the prototype indicates that the proposed method meets the criterion of "novelty."

 The essence of the proposed method is illustrated as follows.

 In the process of operating chemical objects using heavy metals and applying toxicity to reduce their toxicity (for example, in the production of solid fuels), organophosphorus compounds such as TBP are extracted, in which, after extraction of the main share of toxic impurities in the waste composition, an insignificant amount of heavy metal impurities remain, not amenable to final and complete isolation. The proposed method allows, in contrast to the prototype, to obtain final solid products, stable under variable climatic conditions of the middle band, using low temperatures in the process of single-stage heat treatment of a mixture of waste with a binder.

 It was experimentally shown that such a regime is realized so effectively when alkaline earth metals are used as a binder from the carbonate group.

C₄H₉H₂PO₄+MeO₂(NO₃)₂ --->C₄H₉MeO₂PO₄+2HNO₃, (2)
2C₄H₉H₂PO₄+CaMg(CO₃)₂---> (C₄H₉)₂CaMg(PO₄)₂+2H₂CO₃ (3)
Выделяющийся горючий газ по (1)для случая использования ТБФ может быть направлен для повторного использования в процессе в качестве топлива для термического разложения экстрагента.Organic waste is pre-mixed with a binder in a ratio of 1: 3 to 1: 5, their mixture is fed to the reactor, where the heat treatment is carried out at the boiling point of TBP, as a representative of the group of organophosphorus compounds. In this case, chemical reaction processes occur in the reaction volume, expressed by the following equations of chemical reactions:

C ₄ H ₉ H ₂ PO ₄ + MeO ₂ (NO ₃ ) ₂ ---> C ₄ H ₉ MeO ₂ PO ₄ + 2HNO ₃ , (2)
2C ₄ H ₉ H ₂ PO ₄ + CaMg (CO ₃ ) ₂ ---> (C ₄ H ₉ ) ₂ CaMg (PO ₄ ) ₂ + 2H ₂ CO ₃ (3)
The emitted combustible gas according to (1) for the case of using TBP can be sent for reuse in the process as a fuel for thermal decomposition of the extractant.

 Moreover, part of the liquid phase (according to equation 1) in the form of butylphosphoric acid interacts with nitric acid salts of toxic metals in organic waste with the formation of solid butylphosphate compounds of these metals. Another part of the liquid phase is associated with a bonding agent from the group of alkaline earth metal carbonates, for example, dolomite (according to equation 3), forming a solid phase of alkaline earth metal butyl phosphates. The resulting solid phase is stable and sparingly soluble, as experimental studies have shown; Thus, when boiling for more than 14 hours, no corresponding chemical processes were observed, indicating the instability of the products. Such solid products comply with environmental safety requirements and are considered suitable for subsequent disposal in soil.

 In this case, a significant decrease in the initial volume of the mass of utilized waste occurs, of the order of ~ 5 times.

The experimentally substantiated choice of the temperature regime of heat treatment. At temperatures below the boiling point of the organophosphorus compound, the completeness of its decomposition and, consequently, the completeness of binding of toxic elements, ultimately reducing the efficiency of utilization, are not realized. If the upper limit is exceeded over the declared value (350 ^o C), an unproductive over-expenditure of thermal energy occurs, and in addition, there is a possibility of a thermal explosion under the conditions of accumulation of gaseous decomposition products in the reaction volume. A significant influence on the degree of extraction of toxic elements is provided by the optimal choice of ratios of interacting reagents. It has been experimentally confirmed that in the case of a decrease in the amount of binder relative to the mass of waste disposed of less than 1: 3 in the reaction volume, a sufficient amount of reagent is not provided for complete binding of heavy metals, as well as the completeness of binding of the intermediate reaction product, butyl phosphoric acid, as a result of which there will be no significant decrease volume of hardening mass. If the amount of the binder is exceeded in excess of 1: 5 relative to the mass, a significant decrease in the volume of the utilized mass is not realized and unreasonable overspending of the raw material occurs.

 Thus, the use of the proposed method in the entire volume of materials, modes and operations allows us to simplify the prototype method, reduce the complexity and increase the efficiency of the extraction of toxic elements while reducing the volume of utilized mass ~ 5 times.

 The possibility of industrial implementation of the proposed method is confirmed by the following examples of specific performance.

 Example 1. Organic liquid waste containing tributyl phosphate as spent extractant was subjected to disposal at the previous stage of extraction and removal of the bulk of heavy metal impurities, for example, from the REE group.

Under laboratory conditions, preheated to 80-100 ^o C calculated volume flask supplied with a mixture of TBP Ce impurities in an amount of about 0.5 g per liter of volume of the liquid phase of the waste, as well as dolomite based on 100 parts by weight waste 300 wt. h. dolomite. The temperature is gradually brought up to 289-300 ^o C (temperature, boiling point TBP ("Chemistry Handbook", M; Izd. "Chemistry", 1966, p. 562, table: properties of organic compounds) and the reaction mixture is maintained until the bubbles of the evolved gas are completely removed during the interaction of the reagents and the hardening of the mass. Solid waste products were tested for resistance to extreme storage temperatures. According to experimental studies in the proposed method, the indicators of the final waste disposal products can be presented in the form of the following table.

 An additional technical result is to expand the range of natural materials from the group of alkaline earth metal carbonates.

 The table shows that when using the claimed temperature regime of heat treatment, using natural minerals from the number of carbonates in alkaline earth metals and the ratio of reagents as a binding agent, higher utilization efficiency, a reduction in volume of almost 5 times, with less labor and costs compared with the prototype .

Claims (2)

1. The method of disposal of liquid organic waste containing organophosphorus compounds by thermal decomposition of their mixture with a binder and curing, characterized in that the organic waste is fed into the reactor simultaneously with a binding agent, which is used alkaline earth metal carbonates from among natural minerals, based on for every 100 parts by weight organic waste add 300 to 500 parts by weight a binder, then the mixture is subjected to heat treatment in the range from the boiling point of the organophosphorus compound to 350 ^o C to complete curing of the mixture.  2. The method according to claim 1, characterized in that the natural mineral dolomite, or calcite, or magnesite is used as a binder.

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