Method for reducing content of polycyclic aromatic hydrocarbons in coal tar pitch

Abstract

The invention discloses a method for reducing the content of polycyclic aromatic hydrocarbons in coal tar pitch. The method comprises the following steps: adding a potassium hypermanganate modifier into distilled water, and uniformly mixing to obtain a potassium hypermanganate solution; fully freezing original coal tar pitch at the brittleness temperature, grinding and screening to obtain coal tar pitch powder with the particle size of less than 80 meshes, adding the coal tar pitch powder into the prepared potassium hypermanganate solution at the normal temperature, and stirring at a constant speed for reaction at the room temperature to obtain modified coal tar pitch. The method is carried out at the normal temperature; the content of high-activity carcinogens, namely polycyclic aromatic hydrocarbon substances in the obtained modified coal tar pitch is greatly reduced; moreover, the process is simple to carry out, saves energy, reduces consumption, cannot cause secondary pollution and is easy for industrialized production.

Description

technical field [0001] The invention relates to a method for modifying coal tar pitch, in particular to an environment-friendly method for modifying coal tar pitch using potassium permanganate as a modifying agent. technical background [0002] Coal tar pitch is a bulk product obtained after deep processing of coal tar. my country is a major producer of coal tar pitch. In the last century, coal tar pitch was widely used in road paving. The content of polycyclic aromatic hydrocarbons in coal tar pitch is relatively high, among which strong carcinogens such as benzopyrene A large amount exists in coal tar pitch. With the enhancement of people's awareness of environmental protection, the application of coal tar pitch is largely restricted due to its potential toxicity. However, with the increasing shortage of oil resources in recent years, it can be used for road paving. Therefore, it is particularly important to carry out low-toxicity modification of coal tar pitch so that it ca...

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Problems solved by technology

[0005] For example, "Reducing Benzo(a)pyrene Content of Coal-tar-pitch Modified by Styrene-butadiene Rubber Through Dynamic Vulcanization" in 2012, page 292-300 of volume 743-744, the reaction uses SBR as a modifier and sulfur as a cross-linking agent agent, reacted at 180°C with a stirring speed of 4000rpm for 30 minutes, and the content of benzopyrene was reduced by nearly half, but the process was complicated and the high temperature energy consumption was large

[0006] 2014 "Research on Coal Tar Pitch Toxicity Reduction and Its Performance" Issue 01-03 and 08, the document reported that 3% PS, 7% PEG, 5% paraformaldehyde and 0.5% polyphosphoric acid and other mixtures to process coal tar pitch, the content of poisons contained in the obtained modifier is greatly reduced, and the effect is obvious, but it is obvious that this method involves many modifiers and the cost is high

[0008] The publication number is CN103450693A, and the name is "composite modified coal tar pitch and its preparation method". The main raw materials are coal tar pitch and residual oil, and the polymer materials with modifiers of 0-20wt% are waste rubber, most polymers , benzaldehyde, paraformaldehyde, trioxane polyethylene glycol, etc., and 0-5wt% additives such as polyphosphoric acid, elemental sulfur, etc., after treatment, the content of benzopyrene in the modified coal tar pitch is reduced by 30-70%, However, many modifiers are involved and the dosage is large, which makes the modification cost higher and limits the industrial application of coal tar pitch

[0009] Most of the above-mentioned coal tar pitch modifiers are limited to polymers, and the dosage is about 20% of the coal tar pitch, or directly adding petroleum pitch to the coal tar pitch can more or less reduce the content of toxic substances in the coal pitch, but most of the process It is cumbersome, not only uses a large amount, but also is expensive, and the space for reducing toxicity is limited, which greatly limits the application of coal tar asphalt pavement