JP4483558B2 - Cement manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a cement in which a waste powder fire extinguishing agent is added to a cement firing step in which a cement clinker is produced by preheating and burning a cement raw material with a high temperature gas.

Than before, chemical powder is periodically checked, refilled with a new one, or when the deficiency occurs in fire extinguishing devices are collected together with firefighting, the powder extinguishing Thereby no longer needed The drug is treated as industrial waste.
However, in recent years, as environmental problems have become more important, a method for treating powder fire extinguishing agents accumulated as industrial waste has become a problem.

Under such circumstances, as disclosed in Patent Document 1, a method of turning a powder fire extinguisher into a fertilizer has been studied. According to the method described in this document, the powder fire extinguishing agent can be used as a fertilizer by performing a pulverizing treatment and applying a hydrophilization treatment that improves wettability.
However, this powder fire extinguishing agent has a problem that it takes time and cost to make the powder hydrophilic.

JP 2003-171665 A

  Therefore, the present invention introduces a powder fire extinguishing agent that is no longer necessary (hereinafter referred to as “waste powder fire extinguishing agent”) into the cement firing process, and processes the cement while minimizing time and costs. The object is to provide a method of manufacturing.

  In the invention of claim 1, the cement raw material is preheated with a high temperature gas fed from a rotary kiln in a preheater and then fired with the high temperature gas in the rotary kiln to produce a cement clinker. A method for producing cement, characterized in that a waste powder fire extinguishing agent having a particle size of 180 μm or less that generates ammonia gas is introduced into the high-temperature gas at 600 ° C. to 1200 ° C.

The invention according to claim 2 is the method for producing cement according to claim 1 , wherein the waste powder fire extinguishing agent contains at least one of ammonium sulfate and ammonium phosphate.

According to the first aspect of the present invention, when a waste powder fire extinguishing agent having a particle size of 180 μm or less is introduced into a high-temperature gas at 600 ° C. to 1200 ° C. in the cement firing step, the waste powder fire extinguishing agent having a small particle size is Efficiently dispersed in hot gas for early thermal decomposition. As a result, the waste powder fire-extinguishing agent can be detoxified while minimizing time and cost in parallel with cement production.
At this time, since the discarded powder fire extinguishing agent generates ammonia gas by thermal decomposition, the effect of reducing NOx generated in the cement firing step and reducing the NOx concentration released to the outside is also obtained.

A discarded powder fire extinguishing agent having a particle size of 180 μm or less is put into a high-temperature gas in the high-temperature gas in the calcining furnace or in the kiln bottom, above the cement raw material supply port provided in the kiln-bottom housing. Therefore, it can disperse | distribute in the hot gas which blows up, and can process stably and efficiently. Thus, waste powder fire extinguishing agent, was mixed into the cement clinker to be produced, without adversely affecting the quality of the cement, Ru preferred der to be able to maintain the quality of the cement.

Therefore, the invention described in claim 1 is particularly suitable for use in the treatment of a powder fire-extinguishing agent containing at least one of ammonium sulfate and ammonium phosphate as described in claim 2 .

  Hereinafter, the method for producing cement according to the present invention will be described.

First, the apparatus used for the cement manufacturing method of this invention is demonstrated using FIG.
As shown in FIG. 1, this apparatus includes a preheater 1 for preheating cement raw material, a calcining furnace 2 for pre-calcining the preheated cement raw material, a rotary kiln 4 for combusting and decomposing the cement raw material into a cement clinker, and a cement The clinker cooler 6 for cooling the clinker is roughly constituted.

  The preheater 1 is provided with four tanks of cyclones (1a, 1b, 1c, 1d). The first stage cyclone 1a is arranged at the top, and two tanks of cyclones (1a, 1c) are on the left side in the figure. However, two tanks of cyclones (1b, 1d) are alternately arranged in the vertical direction on the right side in the figure.

  Between the alternately arranged cyclones (1a to 1d), cement raw material supply pipes 11 for supplying cement raw material are provided from the lower central portion of the former cyclone to the side surface of the latter cyclone. Further, an exhaust pipe 12 for supplying a high-temperature gas supplied from the rotary kiln is provided from the upper central portion of the rear cyclone to the side surface of the front cyclone.

  Further, the first-stage cyclone 1a is provided with an exhaust pipe 12 for releasing the high-temperature gas in the preheater sent from the rotary kiln to the outside at the center of the upper part, and a cement having an opening valve 13 on the side surface. A raw material supply pipe 11 is connected.

  Furthermore, a calcining furnace 2 is connected to the preceding stage of the last-stage cyclone 1d, and the calcining furnace 2 is provided with a coal charging port 21 and a chemical addition port A1. A hot gas introduction pipe from the kiln bottom housing 32 is connected to the bottom of the calcining furnace 2 provided with the chemical addition port A1.

  On the other hand, the lower part of the cyclone 1d in the final stage is connected to a riser pipe 31 for supplying cement raw material to the rotary kiln 4, and this riser pipe 31 is connected to the kiln bottom part 3 of the rotary kiln 4 together with the kiln bottom housing 32. It is composed.

  A chemical addition port A <b> 2 is provided in the kiln bottom housing 32 constituting the kiln bottom portion 3 and above the cement raw material supply port 33. Note that a drug addition port A2 may be provided above the supply port 33 of the riser 31.

  Further, the kiln butt housing 32 holds the rotary kiln 4 rotatably together with the pre-kiln housing 5 provided at the other end of the rotary kiln 4. In addition, a combustion burner 41 is provided in the front furnace housing 5.

A clinker cooler 6 is continuously provided below the front furnace housing 5.
A blower 61 is provided on an end surface of the clinker cooler 6 facing the rotary kiln 4, and a discharge port 62 is provided on the bottom surface.

Next, an embodiment of a cement manufacturing method according to the present invention will be described using the above-described manufacturing apparatus. Incidentally, the solid line arrows in FIG. 1, showing a flow of cement material (cement kiln) c, arrow dashed line denotes the flow of hot gas g.

  In FIG. 1, first, a cement material c is introduced from a cement material supply pipe 11 with the opening valve 13 opened. Then, the cement raw material c is supplied to the cyclone 1a and is heated while rotating along with the high temperature gas in the exhaust pipe 12 rising from the cyclone 1b. Here, the high temperature gas g (about 300 ° C.) is discharged from the exhaust pipe 12 connected to the upper central portion of the cyclone 1a.

Next, the cement raw material c descends along the inner wall of the cyclone 1a, and is further supplied from the cement raw material supply pipe 11 to the cyclone 1b.
Similarly, the cyclone 1b descends while being heated in association with the high temperature gas g (about 500 ° C.) and the high temperature gas (about 600 ° C.) in the cyclone 1c.

  Then, it is supplied to the calcining furnace 2, burned by the combustion of the coal fuel supplied from the coal inlet 21, and then blown up by the high temperature gas g rising from the kiln butt housing 32, and the cement raw material A supply pipe 11 supplies the cyclone 1d.

  Here, the waste powder fire extinguishing agent is introduced downward into the ascending high-temperature gas g from the agent addition port A1. As this waste powder fire extinguishing agent, a mixture having an average particle diameter of 180 μm or less and an ammonium phosphate and sodium bicarbonate in a weight ratio of 1: 0.8 to 1.2 is used. In addition, although it is understood that ammonium phosphate is mixed with phosphorus in the manufactured cement and has an adverse effect, when it is mixed so that the phosphorus component is less than 1% with respect to the cement of the final product, There is no problem with cement quality.

The waste powder fire extinguishing agent charged in the high temperature gas g has a particle size as small as 180 μm or less, so it is efficiently dispersed in the high temperature gas g and thermally decomposed to generate ammonia gas.
As this ammonia gas, NOx in the high-temperature gas introduced into the calcining furnace 2, NOx generated by the combustion of coal supplied from the coal inlet 21, and the like, as shown in the following reaction formula, NOx emission is reduced because it is decomposed and released to the outside.
NO ₂ + NO + 2NH ₃ → 2N ₂ + 3H ₂ O

  Next, the cement raw material c charged into the cyclone 1d descends the rising pipe 31 from the cyclone 1d and is supplied to the kiln bottom housing 32.

Further, the same waste powder fire extinguishing agent as described above is introduced into the high temperature gas g (about 1100 ° C. ) blown from the rotary kiln 4 downward from the agent introduction port A2 in the kiln bottom housing 32. Then, in the same manner as described above, since the particle size of the waste powder fire extinguishing agent is as small as 180 μm or less, it is efficiently dispersed in the high temperature gas g and generated by the combustion of oxygen and nitrogen supplied from the combustion burner 41. Decomposes NOx.

  Next, the cement raw material c partially mixed with the cement clinker is supplied into the rotary kiln 4 and becomes a cement clinker c in the rotating rotary kiln 4.

  Next, the cement clinker c is supplied to the clinker cooler 6 and cooled by the blower 61 in the clinker cooler 6. Then, it discharges | emits from the discharge port 62 and is supplied to the finishing process which is the next manufacturing process.

  On the other hand, the air heated by cooling the high-temperature cement clinker c is supplied into the rotary kiln 4. In the rotary kiln 4, the air further becomes a high-temperature gas by the combustion of the combustion burner 41 and rises to the calcining furnace 2 and the preheater 1.

  According to the above-described embodiment, the waste powder fire-extinguishing agent is thermally decomposed by being put into the high-temperature gas in the calcining furnace 2. Further, NOx generated by the combustion of coal fuel supplied from the coal inlet 21 can be reduced and immediately reduced. Furthermore, since about 1000 degreeC high temperature gas which blows in the said location is supplied toward the downward direction, it is disperse | distributed in high temperature gas and is processed stably and efficiently.

  Similarly, it is thermally decomposed by introducing it into the high-temperature gas in the kiln bottom housing 32. Further, by introducing the gas into the high temperature gas above the cement raw material supply port 33 in the kiln bottom housing 32, NOx generated by the combustion of oxygen supplied from the combustion burner 41 and nitrogen can be immediately reduced. it can. Furthermore, since it supplies downward about the hot gas of about 1100 degreeC which blows up in the said location, it is disperse | distributed and it processes stably and efficiently. Thereby, the quality of the cement manufactured can be maintained.

  Moreover, since the chemical | medical agent with an average particle diameter of 180 micrometers or less is used as a waste powder fire extinguisher, it is efficiently disperse | distributed in high temperature gas and is thermally decomposed at an early stage. In addition, by using a mixture of ammonium phosphate and sodium bicarbonate in a weight ratio of 1: 0.8 to 1.2, ammonium phosphate is introduced as a mixture with sodium bicarbonate. Also dispersed in cement. For this reason, the influence of phosphorus can be reduced and the quality of cement can be maintained.

  In addition, this invention is not limited at all by the above-mentioned embodiment. For example, although ammonium phosphate and sodium bicarbonate were used as waste powder fire extinguishing agents, ammonium sulfate and other particles having a particle size of 180 μm or less that generate ammonia gas by thermal decomposition can be used.

  Moreover, although the chemical | medical agent addition port (A1, A2) was provided in the inside of the calcining furnace 2 and the kiln bottom housing 32 above the cement raw material supply port 33, you may provide in any one.

  Using the manufacturing apparatus described above, 0 kg, 2 kg, 5 kg, 7 kg, or 10 kg of the waste powder fire extinguishing agent used in the above embodiment was added to the cement raw material 1t, and a cement clinker was manufactured while processing. At this time, Table 1 shows the concentration of NOx released to the outside from the exhaust pipe 12 and the reduction rate of the NOx concentration compared with the case where the waste powder extinguishing agent was not added (0 kg of the waste powder extinguishing agent).

  Next, in the finishing step, a clinker and an appropriate amount of gypsum were mixed and ground to produce a cement. Table 1 shows the CaO ratio (% by mass) of each cement thus obtained. Further, the setting start time and setting time of each cement, the compressive strength when allowed to stand for 3 days after setting, and the compressive strength when allowed to stand for 28 days are based on JIS R 5201. Measured and shown in Table 1.

  As can be seen from Table 1, it can be seen that even if 10 kg or more of the waste powder fire extinguishing agent is added to the cement clinker 1t, it can be treated. It can also be seen that as the amount of waste powder extinguishing agent added increases, the amount of NOx released to the outside decreases.

  Furthermore, even if the waste powder fire extinguishing agent is added or the amount added is increased or decreased, there is no significant change in the setting time and setting time of the cement, and when left for 3 days after setting and when left for 28 days. It can be seen that there is no significant change in compressive strength. Thereby, even if a waste powder fire extinguishing agent is added, it turns out that it mixes in the cement clinker manufactured and can maintain the quality of cement, without having a bad influence on the quality of cement.

It is the cross-sectional schematic diagram which showed one Embodiment of the manufacturing apparatus which can be used for the cement manufacturing method of this invention.

Explanation of symbols

A1, A2 ... chemical addition port c ... cement clinker (cement raw material)
g ... Hot gas (exhaust)
DESCRIPTION OF SYMBOLS 1 ... Preheater 1a, 1b, 1c, 1d ... Cyclone 2 ... Calciner 3 ... Kiln bottom part 4 ... Rotary kiln 5 ... Front kiln housing 6 ... Clinker cooler 11. ..Raw material supply pipe 12 ... Exhaust pipe 21 ... Coal input port 31 ... Rise pipe 32 ... Kilder bottom housing 33 ... Cement raw material supply port 41 ... Combustion burner 61 ... Blower 62 ... Discharge port

Claims (2)

  The cement raw material is preheated with a high-temperature gas sent from a rotary kiln in a preheater, and then calcined with the high-temperature gas in the rotary kiln to produce ammonia gas by thermal decomposition when producing a cement clinker. A method for producing cement, characterized in that the waste powder fire-extinguishing agent is put into the high-temperature gas at 600 ° C to 1200 ° C. The method for producing cement according to claim 1, wherein the waste powder fire-extinguishing agent contains at least one of ammonium sulfate and ammonium phosphate .

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