JPS60180913A - Method for neutralizing modified potassium sulfate by dry process - Google Patents

Abstract

PURPOSE:To neutralize modified potassium sulfate by a simple dry process without requiring drying by adding a proper amount of a powdery neutralizing agent and a very small amount of water to the modified potassium sulfate obtd. by reacting sulfuric acid with potassium chloride by a dry process, mixing them, granulating the mixture under compression, and crushing the granules. CONSTITUTION:To modified potassium sulfate contg. unreacted sulfuric acid obtd. by reacting sulfuric acid with potassium chloride by a dry process are added a powdery neutralizing agent by an amount (equiv.) 0.5-2, preferably about 0.8-1.5 times the amount of said unreacted sulfuric acid and water or steam by 0.03-1wt% of the amount of said modified potassium sulfate, and they are mixed preferably at 0-200 deg.C for 1min-1hr with a suitable blender. One or more among calcium hydroxide, calcium oxide, magnesium oxide and magnesium carbonate are used as said neutralizing agent. The mixture is granulated under compression with a roll press, a briquette machine, an extruder, a tablet machine or the like, and the granules are crushed. The crushed product is optionally sieved with a sieve of 50 meshes (Tyler), and both plus sieve and minus sieve are used as starting materials for fertilizer. The minus sieve may be granulated.

Description

[Detailed description of the invention] The present invention relates to a method for dry neutralizing potassium sulfate.

More specifically, the present invention provides a neutralization method in which modified potassium sulfate containing unreacted sulfuric acid is mixed with a predetermined amount of a neutralizing agent such as calcium hydroxide and a very small amount of water or steam, and neutralized by compression granulation. Regarding.

In recent years, bulk blend fertilizers have been manufactured and used using granular chemical fertilizers as the main raw material. As is well known, bulk blend fertilizer is a fertilizer in which various fertilizing ingredients are mixed together in granular form and stored and applied at a predetermined fertilizer ingredient ratio. Therefore, a granular material is required as a raw material for potash fertilizer. Potassium sulfate, which is used as a raw material for potash fertilizer, is
It is usually produced by dryly reacting potassium chloride and sulfuric acid, but the modified potassium sulfate obtained in this way usually contains several percent of sulfuric acid as unreacted sulfuric acid (described in detail later). If shaken modified potassium sulfate is visually granulated as a potash fertilizer for bulk blending, it becomes impossible to neutralize unreacted sulfuric acid in the granulated product. Therefore, conventionally, before the granulation, the modified potassium sulfate was mixed with an alkaline material as a neutralizing agent and a considerable amount of water (for example, 5 to 8% by weight/
After completing the neutralization reaction, the neutralized modified potassium sulfate was first dried using a dryer or the like, and the resulting powder was granulated. Furthermore, unlike other fertilizing ingredients, no effective granulation method has been developed for modified potassium sulfate.

Therefore, compression granulation method is adopted. Such conventional methods therefore require a neutralization step and a drying step before granulating the modified potassium sulfate.

Therefore, if neutralization and granulation of modified potassium sulfate (unneutralized amount) can be performed simultaneously, the above-mentioned neutralization step and drying step can be omitted, and energy saving and manufacturing process can be simplified.

However, in granular or powdered modified potassium sulfate produced by directly granulating or crushing the mixture of modified potassium sulfate and a neutralizing agent, the neutralization reaction gradually progresses during subsequent storage. Due to the high heat of the neutralization reaction, part of the moisture that had become crystal water is liberated, and the presence of this moisture further promotes the neutralization reaction, accompanied by a so-called caking phenomenon in which granular potassium sulfate adheres to each other. It turned out that. Such a consolidation amount cannot of course be used for bulk blending.

The present inventors have conducted intensive research on a dry neutralization method for modified potassium sulfate that can omit the neutralization step and drying step and does not cause caking accompanying the progress of neutralization after granulation and crushing. As a result, surprisingly, if significantly less water or steam than was used in the conventional dry neutralization process before granulation is mixed with modified potassium sulfate containing unreacted sulfuric acid, the neutralization reaction and heat generation during mixing can be significantly reduced. The present invention was completed based on the knowledge that the modified potassium sulfate powder can be easily and uniformly mixed in a short time and granulated and crushed directly because the fluidity of the modified potassium sulfate powder is not impaired.

Incidentally, the neutralization reaction in the above case progresses relatively quickly during the granulation and disintegration process, and is almost complete by the time the disintegration is completed.
No granules obtained by the crushing and no caking during subsequent storage of the granules are observed.

As is clear from the above description, the purpose of the present invention is to provide a novel dry neutralization method for modified potassium sulfate, which is based on the premise of producing granulated products of modified potassium sulfate (note: powder is also produced). fish.

From another point of view, an object of the present invention is to provide a compression granulation method for modified potassium sulfate that does not require a neutralization step or a drying step.

The present invention has the following main configuration (1) and the following embodiment configurations (2) (1) to (4).

(1) To the modified potassium sulfate containing unreacted sulfuric acid obtained by dryly reacting sulfuric acid and potassium chloride, to the unreacted sulfuric acid,
0.5 to 2 equivalents of calcium hydroxide.

Mixing one or more powdered neutralizing agents selected from calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide, or magnesium carbonate and 0.03 to 1% by weight of water or steam with respect to the modified potassium sulfate, A dry neutralization method for modified potassium sulfate, which comprises compressing and granulating the mixture and then crushing it.

(2) The method according to item (1) above, wherein the crushed amount is sieved to obtain particles with a particle size larger than 50 mesh (Tyler) and powdery particles with a particle size of 0 mesh or less.

(3) The method according to item (1) above, wherein the mixing is carried out at 0°C to 200°C for 1 minute to 1 hour.

(4) Roll press and briquette machine for compression granulation.

, an extruder, or a tablet machine.

The configuration and effects of the present invention will be explained in detail below.

The modified potassium sulfate used in the present invention is prepared by mixing sulfuric acid and potassium chloride in the ratio of 1 mole of the former and 2 moles of the latter in the absence of moisture.
Note, the following formula (1)) approximately 100℃, latter part (note, the following formula (2)
)) Manufactured by reacting at approximately 300 to 400°C・H2SO4+ KC1+KHS04+ HCI (1st
Stage) (1) KH8O4+ KC1+KISO4+ I(
Cl (2nd stage) (2) Since the reaction in each stage is a heterogeneous phase reaction, it does not proceed 100%, and the reactants in the 2nd stage contain small amounts of H2SO4゜KCI and KHSO4. . Especially KCI and KHS (k is H2SO
Even when reacting 4 and 2 KCI, each
It is often used in amounts on the order of 5% by weight.

As the unreacted sulfuric acid, the above-mentioned H2SO4 and KHS are used.
In addition to O4, there is potassium pyrosulfate produced by the following formula (3). Potassium pyrosulfate is produced by thermal decomposition of acidic potassium sulfate as shown in the following formula.

2KHSO4d Ka 3207-17 H20(3)
Potassium pyrosulfate reacts with water and returns to K HSOs.

As a neutralizing agent used for wood/invention, it can react with the reactive acid content in unneutralized potassium sulfate at 0 to 200℃, and the product (sulfate) after the reaction becomes potassium sulfate as a fertilizer ingredient. It can be used as long as it does not add any harmful effects to the product. in particular,
Calcium hydroxide, calcium oxide, calcium carbonate,
One or more compounds selected from calcium or magnesium compounds such as magnesium hydroxide, magnesium oxide, or magnesium carbonate can be used. For example, it is preferable to use a powder with a particle size of 100 mesh (the same goes for Tyler and below), but a granular product with a particle size of 20 mesh is undesirable. The amount is 0.5 to 2 times equivalent, preferably 0.8 to 1.5 times equivalent, relative to the sulfuric acid content. If the amount is less than 0.5 times equivalent, the acidity of the potassium sulfate after neutralization will be extremely high (low pH), making it unsuitable for use as a bulk blend fertilizer. This is not desirable because the concentration of component (&0) tends to decrease.

The water or steam used for neutralization in the present invention is 0.03 to 1% by weight, preferably 0.05% by weight, based on the modified potassium sulfate.
The mixing method of the modified potassium sulfate of 0 or more to be used at ~0.5% by weight, the neutralizing agent, and water or steam is not limited, but
Three types of mixed raw materials are charged simultaneously or sequentially into an open or closed mixer and heated to a temperature of 0 to 200°C, preferably 15 to 100°C.
Mix at 110° C. for 1 minute to 1 hour, preferably 5 minutes to 30 minutes. The temperature of the steam used is not necessarily 100
The temperature is not limited to 100°C or above, but if the pressure inside the closed mixer is maintained at a reduced pressure of, for example, 100 mg, steam at a temperature of less than 100°C, for example 80°C, can be used. The mixer is not limited as long as it can mix like powder in a short time, and for example, a ribbon blender, a V-type blender, a seed blender with a stirrer, etc. can be used.

During mixing, some of the unreacted sulfuric acid begins to react with the neutralizing agent, but
Since the mixing time is shorter, for example by 175 to 1/100 l/100, than the time required for compression granulation and crushing in the next step, there is no significant temperature rise in the mixer due to neutralization heat. The mixing step can be carried out not only batchwise but also continuously.

The resulting mixture (modified potassium sulfate, neutralizing agent and water) is
It is fed to the compression granulation and crushing steps, which are the main steps of the method of the present invention. Since the mixture is a powder with good fluidity, the supply can be carried out smoothly.

Modified potassium sulfate cannot be granulated using a pan or plunger like other fertilizer ingredients or composite fertilizer raw materials, so granulation is performed using a compression molding machine such as a roll press, briquette machine, extruder, or tablet machine. . For example, since the residence time of the above mixture treated with a roll press is extremely short, 20 seconds to 1 minute, the neutralization reaction between the unneutralized sulfuric acid and the neutralizing agent in the mixture is rather delayed after granulation. Processing proceeds substantially up to and after crushing (11!i minutes, etc.). The time for crushing and sieving after granulation molding is 30
minutes to 5 hours, preferably 1 to 3 hours.

During this time, the neutralization reaction is substantially completed. The reason why the neutralization time is short even though the moisture content is extremely low is that compression granulation increases the bulk density in the mixture, so the movement speed of moisture and sulfuric acid in the powdered mixture increases. It is presumed that this is because it is significantly faster than that of . During this time, due to the heat of neutralization, part of the water evaporates from the surface of the briquette, and the other part becomes water of crystallization of one of the salts.

The molded compression granulated product is crushed by a crusher, for example, and the crushed amount is processed by a sieve to separate it into, for example, a 50 mesh granule and a 50 mesh powder. If so, it is processed again in a roll press or in a tablet machine to form granules. Of course, it is not for bulk blend fertilizers, but for compound fertilizers, powdered mago may be used.

The type of crusher and sieve used and operating conditions follow known methods.The processing conditions for the compressed granulated product or crushed product are room temperature 3.
The obtained granular product or granular product (neutralized denatured potassium sulfate) at 0°C for 5 minutes to 1 hour (residence time of the supplied material) is usually stored in a silo and removed from the bag as needed. Pack it.

According to the dry neutralization method of the present invention, since a neutralization step is not necessary, a neutralization device and the power necessary for its operation are not required. In addition, it is possible to save the drying device for the amount of neutralization and the thermal energy required for its operation. Furthermore, since the neutralization mixture containing a small amount of water and undergoing a neutralization reaction is supplied to the roll press, briquettes are formed smoothly and the yield of granular products after crushing is also good.

Furthermore, since no heat generation or caking is observed during subsequent storage of the obtained granular products or granular products, they can be used without any problem for bulk blend fertilizers or regranulation.

The present invention will be explained below with reference to Examples.

Example: 100 tons of modified potassium sulfate containing 2.8% by weight of neutralized sulfuric acid (HxSOa@calc) were mixed with slaked lime (Ca (containing 80% by weight or more) of 2.3% by weight) The mixture was mixed at room temperature using a container.Meanwhile, the modified potassium sulfate was mixed by spraying 0.2% water by weight using a sprayer.The resulting neutralized mixture was heated to room temperature using a roll press. It was compressed into flakes.

The obtained flakes were crushed at room temperature using a crusher, and the crushed products were subsequently separated into granular and granular products using a sieve.

The granular product (50 tons) was placed in a silo (3 m x 4 m x 10 mH) and left for one week at room temperature. During this time, there was no temperature rise due to neutralization heat in any of the silos, and no caking was observed during the extraction described below.

After the above-mentioned standing period, the above-mentioned granular products and granular products are
They were filled into 0 kg bags, stacked indoors at the height of 3 intestines, and left for 6 months. Next, sample bags were taken out from each bag and the solidification status was inspected according to the stacked height. However, no caking was observed for either the single granule product or the granular product at any height.

Comparative Example The same procedure as in the Example was carried out except that water was not mixed using a sprayer. As a result, the temperature of the granular products in the silo, which was initially 30°C, rose to 80°C after one day and water vapor was generated, and when the granules were taken out one week later, significant caking was observed. On the other hand, the temperature of the granular product in the silo containing granular potassium sulfate (initially 30°C) increased by about lθ°C after one day, but then gradually decreased, and when it was removed after one week, the temperature was particularly low. No consolidation was observed.

In addition, after packing in 30Kg bags, stacking at 3mH, and leaving for 6 months, some caking was observed.

Written amendment to the above procedure December 2, 1982/Japanese Patent Application No. 36943 2 Title of the invention Dry neutralization method of modified potassium sulfate & Relationship with the case of the person making the amendment Patent applicant Osaka City, Osaka Prefecture 3-6-32 Nakanoshima, Kita-ku (530)
(207) Chisso Corporation Representative Sadao Nogi 4, Agent East YX Shinjuku-ku, Tokyo - ``Shuku 2-8-1 (〒160)a
Detailed description of the invention in the specification to be amended.

I Contents of amendment Correct the statement as follows.

(υ Correct “reaction value acid content” in line 7 of the 7th sentence to “unreacted sulfuric acid content”.

(2) Insert ``substance'' after ``like'' in the 5th line from the bottom of page 8.

that's all

Claims (4)

[Claims] (1) To the modified potassium sulfate containing unreacted sulfuric acid obtained by dryly reacting sulfuric acid and potassium chloride, to the unreacted sulfuric acid,
0.5 to 2 equivalents of calcium hydroxide. Mixing one or more powdered neutralizing agents selected from calcium oxide, calcium carbonate, magnesium hydroxide, magnesium oxide, or magnesium carbonate and 0.03 to 1% by weight of water or steam with respect to the modified potassium sulfate, A dry neutralization method for modified potassium sulfate, which comprises compressing and granulating the mixture and then crushing it. (2) The method according to claim (1), wherein the amount of crushed material is sieved to produce granules with a particle size of more than 50 mesh (Tyler) and powders with a particle size of 50 mesh or less. (3) The method according to claim (1), wherein the mixing is carried out at θ°C to 200°C for 1 minute to 1 hour. (4) Roll press and briquette machine for compression granulation. The method according to claim O), which is carried out using an extruder or a tablet machine.