HU186948B - Method for utilizing coal washings by spherical agglomeration - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to a process for preparing an agglomerate having good mechanical and combustion properties from aqueous carbon sludge using a binder.

Methods are known for making aqueous carbon sludge, which is highly polluting to the environment and causes storage problems, suitable for further use.

The utilization of carbon sludge in general, and more particularly its agglomeration, has been reported in numerous patents. (US 4 234 320; DE 29 51; GB 2 024 250 A; DE 27 53 628; US 4 126 426; RB 874 315).

The first step in each of these processes is to mix the aqueous carbon sludge with a with binders - these are predominantly liquid hydrocarbons. The mixing may be carried out mechanically (eg with paddle stirrers), ultrasound or by coalescing high-speed liquid phases, ie hydrodynamically. As a result of the mixing, the granules adhere to the oil emulsified in water and form a well-filterable agglomerate. Generally, it is preferred that the stirring is carried out at a higher temperature. Some descriptions (e.g. US 4,234,320) consider agglomeration to be carried out in two steps.

According to the aforementioned US 4 234 320, an aqueous suspension of a solid is mixed with a hydrocarbon binder with turbulent mixing, the resulting agglomerate is separated from water and non-agglomerated particles, and the agglomerate is transferred to a water-containing mixer having a temperature higher than the binder. - additional binder is added to this mixer and the resulting agglomerate of higher quality is separated from the hot water which is recycled to the cycle by a mobile sieving separator.

The process according to U.S. Pat. No. 4,126,426 differs in particular from the former in that the carbon sludge is separated into two fractions according to the particle size before agglomeration, the smaller particle size (less than 0.1 mm) is agglomerated, separated, and the larger particle - easier to handle - the fraction is added to the agglomerate after dewatering. Liquid hydrocarbons are also used as binders. The process is more effective at higher temperatures.

According to RB 874 315 (Belgian), agglomeration is agitated by hydrodynamic mixing: the liquid hydrocarbon is mixed into the flowing carbon sludge, and the agglomeration and separation is carried out in a filter centrifuge. This patent considers it convenient to form an aqueous emulsion of hydrocarbon prior to mixing with the carbon sludge.

Precise mixing and viscosity data can be found in GB 2 024 250, which states that the agglomeration is preceded by a flotation section to concentrate the dry matter. The advantage of the process seems to be the low oil consumption.

According to DE 27 53 628, agglomeration is carried out with an aqueous emulsion of oil, and after separation it is repeated with non-agglomerated tailings. High boiling oil is used and the efficiency of the process is enhanced by the addition of surfactants. The sludge and water are separated by means of a sieve and the agglomerate is washed by washing from the adherent sludge.

Based on the patents cited above, the generalizable features of the processes employed are as follows;

1. The aqueous carbon sludge is mixed with a liquid hydrocarbon as a binder to form a filterable agglomerate. The mixing methods are varied: various mechanical, hydrodynamic and ultrasonic methods have been described.

2. Agglomeration is more effective if the system temperature is higher.

3. The hydrocarbons used are primarily the various liquid fractions of petroleum and coal distillate products.

4. If necessary, the product is further dried mechanically and / or thermally.

A common disadvantage of these solutions was that the resulting agglomerate had a paste consistency and thus encountered difficulties in further treatment. With the help of known technologies, in no case was the ash content reduced by more than 30%, the quality of the coke and the agglomeration could not be produced at all. A further disadvantage was that a large amount of heavy oils was removed from the agglomerate, thus wasting useful material.

In the prior art, the mixing of the carbon sludge with the agglomerating material and the heating of the mixture each required two separate technological operations, which greatly increased both the time required to carry out the process and the need for equipment.

In our work, we are guided by the goal of overcoming the shortcomings of existing technologies and producing low calorific fuel with high calorific value in the most economical way possible.

In our experiments, it has been found that the addition of a small amount (1-10%) of pitch or crude tar, which may contain 50% pitch, to the fuel or tar oil used as a binder significantly improves the product's filterability, mechanical strength and separation from the barrier. The ash content of the resulting product is reduced by at least 50% and its calorific value increases accordingly.

As a result of our experiments, we have succeeded in developing a process in which stirring and heating are solved in one step. The essence of our technology is that the steam introduced into the color sludge, for example tangentially, is stirred and heated in one step. Our attempts to further eliminate uneconomical mechanical mixing from technology and thus save energy.

We also found that the effect of steam is greatly enhanced by the addition of air, which increases the mixing effect.

It has also been found advantageous to add a surfactant to the carbon sludge as needed. According to our experience, both ionic and non-ionic materials have met the target.

Further experimental experience has shown that the addition of high-quality (low-barrier) porous carbon and the agglomerate obtained as a product to the carbon sludge mixture promotes greater separation of the barley from the granules and also improves the mechanical properties of the agglomerate formed.

If we process carbon sludge which is produced during the coking coal production process, we can reduce the ash content below 12% and thus make the resulting agglomerate suitable for coking. The importance of this fact in the field of energy management is very significant.

The essence of our process with reference to the accompanying flowchart (Figure 1) is described generally below.

The approx. 30% dry matter carbon sludge with a sludge content of approx. 35-40% of the settling tank 1 is fed via the slurry pump 13 to the pre-mixing tank 5 via the heat exchanger 4. In the premixer 5, if necessary, powder-carbon and / or powder-carbon are added. The agglomerate may be mixed in accordance with steps 3 and 3, respectively. 21 reservoirs. The carbon sludge to be agglomerated is agglomerated in a steam reactor 6, optionally tangentially introduced, from tank 2 with heat pump 3 or tar oil preheated by pump 12 on heat exchanger 4 and addition of crude tar and optionally surfactant. Preferably, the oil is sprayed with steam into the mixing vessel where air is simultaneously introduced. The agglomerate produced in the mixing reactor 6 and the separated sludge are recycled via the heat exchanger 4, countercurrently with water recycled from the settler 11 or with water supplementation, to the countercurrent separator 7, the bottom product of which is an oil agglomerate and slurry removed as slurry. The agglomerate leaving the countercurrent separator 7 is dewatered by the mechanical separator 9 and transported to the conveyor system 10 for use or storage. The effluent from the countercurrent separator 7 is mixed with a flocculant known per se in the mixing tank 8 and then discharged into the settler 11, whereupon the sediment is settled for approx. The 40% moisture barrels are pumped into the desiccator with the pump 15. The near mud-free water that appears in the overflow is used in valve 19 via pump 14 to partially feed backflow separator 7 and partly to return to the carbon concentrator through valve 17. The filtrate from the mechanical separator 9 is fed into the same water circulation through valve 18. The following non-limiting examples of embodiments of the process are set forth below.

Example 1

Carbon sludge with a dry solids content of 250 g / l, with a non-flammable residue of 35%, is passed through a heat exchanger at a rate of 4 l / min to the premixer and then to the agglomeration mixer. To the carbon sludge preheated to about 50-60 ° C, heating oil at 20 ° C (light sulfur fuel oil P60 / 130) is added at a rate of 100 g / min. The fuel oil used has a viscosity of 5.2 ° C at 70 ° C and a softening point of 85-95 ° C in the resin. Intensive mixing of the carbon sludge and the additive oil was accomplished by direct steam tangential injection, which was followed by atomization of the introduced oil component and heating of the mixture to 60-90 ° C.

The saturated water vapor at 100-102 ° C used for stirring was pressurized to 0.1 MPa. The agglomerate produced in the agglomeration and the separated sludge are fed through the heat exchanger to the countercurrent separator, the bottom product of which is the slurry leaving as a slurry. The agglomerate leaving the countercurrent separator is dewatered with a vacuum filter and supplied to a conveyor system.

place it in the place of use or storage. The resulting The amount of agglomerate is 0.95-1.0 kg / min. water 9% solid 80% oil content 11% non-combustible residue 17%

In the countercurrent separator 7, the effluent is mixed in the mixing tank 8 with a known booster and then discharged into the settler 11, whereupon the precipitate settles for approx. 40% moisture barrels are delivered to the desiccator.

The amount of infertility produced is 420-450 g / min with a moisture content of 40-42%

The dried 170-180 g barley has an oil content of 1.2-1.3%, a measured carbon content of 3-4%, and a non-combustible residue of 87-89%. The nearly sludge-free water on the settler and the filtrate obtained at the separator are recycled to the water circulation of the coal preparation system.

Example 2

The process was the same as in Example 1, but the same 10% pitch tar oil was used instead of the 3% pitch fuel oil and 0.1% dodecylsulfonic acid Na salt was added to the carbon sludge solids content.

The amount of agglomerate formed is 1.05 kg / min water content 9.5% solids content 80% oil content 10.5% non-combustible residue 17%

The amount of barley produced is 450 g / min water content 43%

Example 3

The technology is essentially the same as in Example 1, except that a pre-fabricated agglomerate is mixed in the premix tank with the initial carbon sludge.

Amount of agglomerate added 60 g / min solids content 75% oil content 16% water content 8.2% non-combustible residue 12.4%

The amount of agglomerate formed is 1.10 kg / min water content 9% oil content 16% solids content 75% non-combustible residue 13.5%

The amount of produced barrels has a water content of 480 g / min 43-44%

The dry matter has an oil content of 1.3% C content 4: 0% non-combustible residue 88%

Example 4

The technology used is identical to that described in Example 1 except that the initial carbon sludge has a lower ash content (25%).

A centrifuge was used for the dewatering process.

The amount of agglomerate formed is 1.05 kg / min. Composition: water 10% oil 10% solids content 80% non-combustible residue 10%

If the starting coal was otherwise suitable for the production of blast furnace coke, the resulting agglomerate would also be of coke quality.

The amount of waste removed was 380 g / min water content 41%

1.2-1.3% of its dry matter is oil, the carbon content of its combustible part is 3.5-4.0%, and its combustible residues 91-91.5%.

Claims (4)

Claims 5 A process for the use of carbon sludge by spherical agglomeration, characterized in that the carbon sludge is optionally mixed with 0.01 to 1.0% ionic or nonionic surfactant, optionally mixed with carbon powder or the final agglomerate and preferably with the solids content of the carbon sludge. Mixed with 2-4% pitch fuel or tar oil or crude tar, agglomerated with pressurized steam of at least 0.02 MPa and concomitantly supplied air; process, recycle the resulting water into the system. ^υ 2. A method according to claim 1 characterized in that the steam is introduced tangentially to agglomeration. Process according to any one of claims 1 or 2, characterized in that the oil for agglomeration is sprayed onto the carbon sludge with the agglomerating steam. 4. A process for the production of a coking product according to any one of claims 1 to 3, characterized in that: Carbon sludge from the production of 30 coking coal is agglomerated.