RU2574929C2 - Processing of oiled scale under conditions of self-propagating high-temperature synthesis - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: claimed process comprises the preparation of the charge by mixing the oiled scale with the content of oil of up to 15% and water of not over 10% with the not oiled scale in the amount of 10-30%. Oil and water are separated in self-propagating high-temperature synthesis. Note here that the combustion reaction is initiated by the feed of oxygen-bearing gas with content of oxygen of up to 50-100% incl. Note here that the combustion wave direction is aligned with that of the gas mass transfer. Oiled scale with water content of 10% is, first, brought to the water content of 10% by spinning or drying.

EFFECT: recovery of scale, fuel saving, high-quality stock for metallurgy.

3 cl

Description

Field of technology: metallurgy, waste processing.

The process of processing oily scale includes the preparation of the mixture and the separation of oil and water in the SHS mode.

The level of technology.

Based on the existing methods for processing oily scale, we can divide them into 3 classes of methods

1. "Wet" methods, turning off the use of solutions of various compositions for the separation of oil. The disadvantage of this class of methods is the accumulation of oil-containing water and the problem of its disposal, as well as the complex and expensive hardware design. Processes can be economically efficient only with the state subsidies or high fines for storing oily scale.

2. Methods of briquetting. The disadvantage of this class of methods is the use of additional materials and binders, the use of sophisticated equipment and the limited use of briquettes in real production.

3. The thermal class of methods. The disadvantage is the use of large amounts of fuel for evaporating (or burning) oil and water from oily scale. In some cases, both the complexity and the high cost of hardware design. The presence of water in oily scale in dumps requires additional "joules", either during drying or in direct processing.

This patent application can be attributed to the thermal class of methods, but it is devoid of their main disadvantage, such as significant fuel costs. The self-propagating high-temperature synthesis mode uses the energy released in a narrow combustion zone (not requiring heating a large volume of the charge), and in fact the energy is stored chemically in pure oxygen when it is received at gas separation cryostations.

There are no analogues to the processing of oily scale in the SHS mode, exactly like using pure oxygen (or mixtures enriched with oxygen), however, the closest application is (21), (22) application: 97115322/02, 09/11/1997, where the SHS mode is not used, but heated air is used to burn oil. A common one is the decision to use a heated oxidizing agent to burn oil and thereby generate energy for the process. However, our method is characterized in that the combustion wave not only and not so much burns the oil, but displaces the main part of the oil and water by successive evaporation, and only part of the oil burns, giving energy to the process. In addition, the hardware design of the method specified in application 97115322/02, 09/11/1997, where separation of the gas-dust mixture is required and fluidized beds are used, is very expensive, and the idea of using gas mixtures enriched with oxygen or pure oxygen is absent in the method.

In addition, in our method, the charge is in a stationary reactor, does not mix and does not move at all during thermal processing, which makes the hardware design of the processing plant simple, and the process itself is economically highly efficient.

1. The preparation of the mixture

1.1. Oily scale with an oil content of up to 15% and water no more than 10% is mixed in the mixer with non-oily scale, which is fed to the granulator mixer in an amount of 10 to 30%, depending on the oil content in the oily scale to prevent it from sticking together and to ensure gas permeability charge layer. Oiled scale with a water content of more than 10% must be pre-processed by centrifugation, drying and other methods to bring up to 10% of the water content.

1.2 The mixture is fed by a belt conveyor to a flow reactor made of ferrous metals.

2. The process of separating oil and water from the prepared mixture in the SHS mode of filtration combustion.

The process of separating oil and water is the movement of the combustion wave from top to bottom of the reactor (directional combustion). The intensity can be controlled by changing the space velocity and oxygen concentration, up to the process attenuation.

The combustion wave is organized by supplying pure oxygen or gas mixtures with a concentration of 50 to 100% oxygen from the top of the reactor and initiating, using a short-term thermal pulse, the upper part of the charge.

A decrease in oxygen concentration, as well as a decrease in its space velocity, leads on the one hand to its more efficient consumption, but on the other hand it reduces the speed of the combustion wave, the time of the secondary burning of the charge, and the productivity of the reactor. The oxygen consumption for oily scale containing 15% oil, 75% iron oxides and 10% water is 150 cubic meters per 1 ton of oil scale, which is cost-effective for cryogenic plants of metallurgical plants, taking into account the consumption of 1-1.5 kW / h electricity for the production of 1 cubic meter of oxygen). The velocity of the front of the combustion wave is 1 cm / min. The amount of oxygen consumed may vary depending on the percentage of oil. With an unknown oil content (up to 15% and water up to 10%), pure oxygen is fed into the reactor with a maximum flow rate in the “breakthrough” mode through the combustion front, then both the concentration (dilution with air) and the flow rate are reduced almost to the decay limit of the combustion wave and maintained automation at this level.

Mass transfer of gases is unidirectional with the movement of the combustion wave. The temperature developed in the combustion wave is more than 600-700 ° C and is sufficient to separate the oil. Since sintering and partial melting of iron oxides takes place, the temperature in the reactor can reach 1500-1600 ° C. It is also possible to initiate a combustion wave from below the reactor while supplying oxygen from below the reactor. Then the oil and water will be displaced upward, but less efficiently, since the gravitational force will act in the opposite direction on the oil and water condensing in the cold regions of the reactor above the combustion wave.

(The start of a combustion wave in opposition to the mass transfer of gases does not allow separating oil and water from the scale, since oil and water have time to cool and condense in the charge layer where the wave has already passed and reduce the gas permeability of the layer, not having time to leave the reactor).

The combustion wave, moving down the reactor, successively displaces the oil and water contained in the charge by evaporation. Water and oil vapors condense in the charge layers below the combustion wave, which are partially heated by the exhaust gases, which also helps to reduce energy costs. Thus, at the end of the reaction, oil and water flow out of the reactor and can either be collected using a refrigeration unit in a tank and sent for processing, or, if this is undesirable for some reason, they can be burnt in the combustion chamber.

In the process of separating oil and water in SHS mode, part of the oil burns out, releasing energy, and the combustion products, including carbon monoxide, are burned together with oil vapor, preferably using a porous afterburning catalyst. Oxygen, if its feed rate is higher than its absorption rate in the combustion wave (breakthrough mode), also contributes to the most complete combustion of exhaust gases and prevents the release of oil vapor and carbon monoxide into the atmosphere.

Since the oil is oxidized and contaminated, as well as the risk of a mixture of carbon monoxide and oxygen and the complexity of the installation due to explosion protection, it is economically feasible to burn it at the outlet of the reactor in the combustion chamber, using both the oxygen “slip” and the catalyst.

Part of the obtained dry oil-free scale is crushed in a jaw crusher to a size of 2 mm or less (you can also use a disintegrator to crush it into dust for better granulation and less adhesion) and return it to the granulation process with oily scale.

Technical result:

As a result of burning oily scale in oxygen in SHS mode, sintered porous magnetically active pieces of a mixture of iron oxides (magnetite and hematite) are obtained containing, in addition, alloying metals such as manganese and chromium, since oily scale is produced at metallurgical plants from various grades of steel , including alloyed with these elements. Thus, the process eliminates waste 3-4 hazard class and at the same time generates high-quality raw materials for the metallurgical industry.

The effectiveness of the SHS regime for processing oily scale is to save fuel, i.e. energy efficiency inherent in SHS processes in general. The process does not generate new waste, unlike “wet” recycling methods. Raw materials do not have application restrictions inherent in briquetting methods, where oil and water are not removed from the scale.

The presence of powerful oxygen stations at metallurgical enterprises, which have low costs for the production of oxygen, as well as a large stock of oily scale dumps (hundreds of thousands of tons) and their continuous generation, creates the economic conditions for the implementation of the process and the use of waste accumulated over decades as a new cheap source of raw materials.

Claims (3)

1. The method of thermal processing of oily scale of metallurgical production, characterized in that the preparation of the mixture by mixing oily scale with an oil content of up to 15% and water no more than 10% with non-oily scale in an amount of 10 to 30%, the separation of oil and water in the mode self-propagating high-temperature synthesis, while initiating the combustion reaction by supplying an oxygen-containing gas with an oxygen content of from 50-100% inclusive. 2. The method according to p. 1, in which the direction of the combustion wave coincides with the direction of mass transfer of gas. 3. The method according to p. 1, in which the oily scale with a water content of more than 10% is previously adjusted to a water content of 10% by centrifugation or drying.