JP2629252B2 - Stabilization method of calcium nitrite aqueous solution - Google Patents
Stabilization method of calcium nitrite aqueous solutionInfo
- Publication number
- JP2629252B2 JP2629252B2 JP7576088A JP7576088A JP2629252B2 JP 2629252 B2 JP2629252 B2 JP 2629252B2 JP 7576088 A JP7576088 A JP 7576088A JP 7576088 A JP7576088 A JP 7576088A JP 2629252 B2 JP2629252 B2 JP 2629252B2
- Authority
- JP
- Japan
- Prior art keywords
- aqueous solution
- weight
- calcium
- calcium nitrite
- nitric acid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000007864 aqueous solution Substances 0.000 title claims description 56
- RAFRTSDUWORDLA-UHFFFAOYSA-N phenyl 3-chloropropanoate Chemical compound ClCCC(=O)OC1=CC=CC=C1 RAFRTSDUWORDLA-UHFFFAOYSA-N 0.000 title claims description 50
- 238000000034 method Methods 0.000 title claims description 16
- 230000006641 stabilisation Effects 0.000 title claims description 3
- 238000011105 stabilization Methods 0.000 title claims description 3
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 35
- 239000000920 calcium hydroxide Substances 0.000 claims description 35
- 235000011116 calcium hydroxide Nutrition 0.000 claims description 35
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 35
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 31
- 229910017604 nitric acid Inorganic materials 0.000 claims description 31
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims description 18
- 239000007789 gas Substances 0.000 claims description 11
- 239000002002 slurry Substances 0.000 claims description 8
- 230000000087 stabilizing effect Effects 0.000 claims description 3
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 claims description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 2
- 238000010521 absorption reaction Methods 0.000 claims description 2
- 239000011575 calcium Substances 0.000 claims description 2
- 229910052791 calcium Inorganic materials 0.000 claims description 2
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 claims description 2
- IOVCWXUNBOPUCH-UHFFFAOYSA-N Nitrous acid Chemical compound ON=O IOVCWXUNBOPUCH-UHFFFAOYSA-N 0.000 claims 1
- 239000013078 crystal Substances 0.000 description 15
- 239000000243 solution Substances 0.000 description 10
- 238000001914 filtration Methods 0.000 description 9
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 description 8
- 238000001556 precipitation Methods 0.000 description 8
- 239000007788 liquid Substances 0.000 description 6
- 239000002244 precipitate Substances 0.000 description 4
- 239000006227 byproduct Substances 0.000 description 3
- 239000004567 concrete Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 159000000007 calcium salts Chemical class 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- -1 chlorine ions Chemical class 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 230000003449 preventive effect Effects 0.000 description 2
- 239000011150 reinforced concrete Substances 0.000 description 2
- LDXJRKWFNNFDSA-UHFFFAOYSA-N 2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-1-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]ethanone Chemical compound C1CN(CC2=NNN=C21)CC(=O)N3CCN(CC3)C4=CN=C(N=C4)NCC5=CC(=CC=C5)OC(F)(F)F LDXJRKWFNNFDSA-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 1
- 241000220317 Rosa Species 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 230000002528 anti-freeze Effects 0.000 description 1
- 239000001506 calcium phosphate Substances 0.000 description 1
- 229910000389 calcium phosphate Inorganic materials 0.000 description 1
- 235000011010 calcium phosphates Nutrition 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Treating Waste Gases (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、消石灰の水性スラリーに一酸化窒素と二酸
化窒素を含有する混合ガスを吸収反応させることにより
得られる亜硝酸カルシウム水溶液の安定化方法に係わ
る。The present invention relates to a method for stabilizing an aqueous solution of calcium nitrite obtained by absorbing and reacting an aqueous slurry of slaked lime with a mixed gas containing nitric oxide and nitrogen dioxide. Related to
亜硝酸カルシウムは、コンクリートの硬化促進剤、鉄
筋コンクリートの防錆剤、防凍剤等として用いられ、そ
の使用の利便から20〜40重量％の水溶液として工業生産
されている。Calcium nitrite is used as a hardening accelerator for concrete, a rust preventive for reinforced concrete, an antifreeze, and the like, and is industrially produced as a 20 to 40% by weight aqueous solution because of its convenience.
（従来の技術） 亜硝酸カルシウム水溶液を効率よく製造する方法とし
て、特公昭52−31318号公報に、NO/NO2モル比１以上の
比率にNOとNO2を含有するガスを消石灰の水性スラリー
に吸収させた後残存消石灰を濾別することによる方法が
開示されている。更に、特公昭55−16969号公報及び特
公昭58−50926号公報には、大規模工業生産のための改
良された方法も開示されている。(Prior Art) As a method for efficiently producing an aqueous solution of calcium nitrite, Japanese Patent Publication No. 52-31318 discloses an aqueous slurry of slaked lime prepared by mixing a gas containing NO and NO 2 at a NO / NO 2 molar ratio of 1 or more. A method is disclosed in which residual slaked lime is filtered off after absorption. Furthermore, Japanese Patent Publication No. 55-16969 and Japanese Patent Publication No. 58-50926 disclose an improved method for large-scale industrial production.
（発明が解決しようとする課題） これら従来の技術では、硝酸カルシウムの副生を極力
避けるために、NOとNO2を含有するガスの供給は、少量
ながら未反応の懸濁消石灰が尚残存する段階で停止さ
れ、この残存する懸濁消石灰はこれを含有する生成亜硝
酸カルシウム水溶液から濾別される。従って、得られた
水溶液は透明であって、副生硝酸カルシウム含有率が低
く、亜硝酸カルシウムを20〜40重量％に含有する水溶液
が効率よく得られるが、この水溶液は低温において結晶
を析出する。(Problems to be Solved by the Invention) In these conventional techniques, in order to avoid by-products of calcium nitrate as much as possible, the supply of the gas containing NO and NO 2 is small but unreacted suspended slaked lime still remains. The step is stopped and the remaining suspended slaked lime is filtered off from the aqueous calcium nitrite solution containing it. Therefore, the obtained aqueous solution is transparent, the content of by-product calcium nitrate is low, and an aqueous solution containing 20 to 40% by weight of calcium nitrite can be obtained efficiently, but this aqueous solution precipitates crystals at a low temperature. .
特に冬期或いは寒冷地においては、貯蔵タンクや製品
輸送容器中でこの結晶の析出が起ると、析出結晶はかさ
ばった状態で沈積するために、貯蔵タンクや輸送容器か
らその排出口を通して亜硝酸カルシウム水溶液を抜き出
す際、円滑な液の排出が妨げられる。この容器内に沈積
した析出結晶の状態をしらべたところ、そのみかけの容
積が０℃の上記亜硝酸カルシウム水溶液中で約10％を占
める程の多量であることが判明した。Especially in winter or cold regions, when this crystal precipitates in a storage tank or product transport container, the precipitated crystal is deposited in a bulky state. When draining the aqueous solution, smooth discharge of the liquid is prevented. Examination of the state of the precipitated crystals deposited in this vessel revealed that the apparent volume was as large as about 10% in the above-mentioned aqueous solution of calcium nitrite at 0 ° C.
上記透明な20〜40重量％の亜硝酸カルシウム水溶液の
低温における不安定性を簡便に解消する方法として、こ
の水溶液を一旦低温に冷却して結晶を析出させた後、そ
の結晶を濾別する方法が考えられるが、この冷却のため
には多大のエネルギーを要するのみならず、低温のこの
水溶液は粘度が高いので濾過することが容易でない。ま
た、上記残存消石灰が懸濁する生成亜硝酸カルシウム水
溶液を濾別する工程において、上記のように低温濾過す
ることも考えられるが、やはり、多大のエネルギーを要
し、濾過することは容易でない。As a method for easily eliminating the instability of the transparent 20 to 40% by weight calcium nitrite aqueous solution at a low temperature, a method of once cooling the aqueous solution to a low temperature to precipitate crystals, and then filtering the crystals. It is conceivable that not only does this cooling require a large amount of energy, but also that the low temperature aqueous solution is not easily filtered because of its high viscosity. In addition, in the step of filtering the formed aqueous calcium nitrite solution in which the residual slaked lime is suspended, low-temperature filtration may be performed as described above. However, a large amount of energy is required, and filtration is not easy.
本発明は、上記方法によって工業生産された20〜40重
量％の亜硝酸カルシウム水溶液を、低温においても結晶
析出を起さないように、簡易かつ効率よく安定化させよ
うとするものである。An object of the present invention is to stably and efficiently stabilize an aqueous solution of 20 to 40% by weight of calcium nitrite industrially produced by the above method so as not to cause crystal precipitation even at a low temperature.
（課題を解決するための手段） 本発明によって安定化される亜硝酸カルシウム水溶液
は、消石灰の水性スラリーに、例えばアンモニアの空気
酸化等によって得られるNOとNO2をNO/NO2モル比１以上
の比率に含有するガスを吹き込むことによって生成させ
たものである。通常、この方法では硝酸カルシウムの副
生を抑制するために、このガスの吹き込みは少量の懸濁
消石灰が残存する段階で停止され、そしてこの残存する
懸濁消石灰を濾別して除くことにより、その濾液とし亜
硝酸カルシウム水溶液が得られる。この方法に用いられ
るスラリー中の消石灰濃度を20〜40重量％程度にする
と、上記の如くして得られた亜硝酸カルシウム水溶液中
には亜硝酸カルシウムが20〜40重量％程度含まれ、副生
硝酸カルシウムはごく僅かである。そして、この得られ
た亜硝酸カルシウム水溶液中には、溶解状態で残存した
水酸化カルシウムが0.1〜0.2重量％程度含まれている。(Means for Solving the Problems) An aqueous calcium nitrite solution stabilized by the present invention is obtained by adding NO and NO 2 obtained by, for example, air oxidation of ammonia to an aqueous slurry of slaked lime at a NO / NO 2 molar ratio of 1 or more. Is produced by blowing a gas containing the same ratio. Usually, in this method, in order to suppress the by-product of calcium nitrate, the blowing of this gas is stopped at a stage where a small amount of suspended slaked lime remains, and the remaining suspended slaked lime is removed by filtration to remove the filtrate. Then, an aqueous solution of calcium nitrite is obtained. When the concentration of slaked lime in the slurry used in this method is about 20 to 40% by weight, the aqueous solution of calcium nitrite obtained as described above contains about 20 to 40% by weight of calcium nitrite, Calcium nitrate is negligible. The obtained aqueous solution of calcium nitrite contains about 0.1 to 0.2% by weight of calcium hydroxide remaining in a dissolved state.
本発明の安定化方法は、この亜硝酸カルシウム水溶液
に硝酸を、該水溶液中の水酸化カルシウム量が0.08〜0.
02重量％となる量加えることを特徴とする。In the stabilization method of the present invention, nitric acid is added to the aqueous solution of calcium nitrite, and the amount of calcium hydroxide in the aqueous solution is 0.08 to 0.
It is characterized in that it is added in an amount of 02% by weight.
本発明に用いられる硝酸としては、10〜55重量％程
度、特に15〜45重量％の水溶液がよい。また、この硝酸
の添加は、亜硝酸カルシウム水溶液の攪拌下に行うのが
好ましい。As the nitric acid used in the present invention, an aqueous solution of about 10 to 55% by weight, particularly 15 to 45% by weight is preferable. The addition of nitric acid is preferably performed while stirring the aqueous calcium nitrite solution.
硝酸の添加量としては、亜硝酸カルシウム水溶液中の
水酸化カルシウム量が0.08重量％以下、好ましくは0.06
〜0.02重量％となる量がよい。The amount of nitric acid added is such that the amount of calcium hydroxide in the aqueous solution of calcium nitrite is 0.08% by weight or less, preferably 0.06% by weight.
A good amount is up to 0.02% by weight.
（作 用） 0.1〜0.2重量％の水酸化カルシウムと20〜40重量％の
亜硝酸カルシウムを含有する亜硝酸カルシウム水溶液
は、５℃でみかけ容積５％の、そして０℃ではみかけ容
積10％のかさばった結晶の析出を起すが、この結晶は水
酸化カルシウムと亜硝酸カルシウムとの複塩である塩基
性亜硝酸カルシウムであることが見出された。本発明に
より加えられる硝酸は、この結晶析出の原因物質である
水酸化カルシウムを水溶性のカルシウム塩に変換し、こ
の結晶析出を防ぐことが見出された。(Action) An aqueous calcium nitrite solution containing 0.1 to 0.2% by weight of calcium hydroxide and 20 to 40% by weight of calcium nitrite has an apparent volume of 5% at 5 ° C and an apparent volume of 10% at 0 ° C. This resulted in the precipitation of bulky crystals, which were found to be basic calcium nitrite, a double salt of calcium hydroxide and calcium nitrite. It has been found that the nitric acid added according to the present invention converts calcium hydroxide, which is the cause of the crystallization, into a water-soluble calcium salt and prevents the crystallization.
上記硝酸の代わりに塩酸を用いるときは、亜硝酸カル
シウム水溶液中に塩素イオンが含まれることになり、こ
の亜硝酸カルシウム水溶液を鉄筋コンクリート用のコン
クリートに添加した場合に鉄筋に腐蝕を起させる原因と
なる。また、硝酸の代りに硫酸、りん酸等難溶性カルシ
ウム塩を形成する酸を用いるときは、この酸の添加によ
って亜硝酸カルシムウ水溶液中に硫酸カルシウム、りん
酸カルシウム等の沈澱が生じ易い。この沈澱は濾別によ
って除くとができるが、そのための濾過工程を必要とす
る。また、有機酸は高価である。従って硝酸が好まし
い。When hydrochloric acid is used in place of the above nitric acid, chlorine ions are contained in the aqueous solution of calcium nitrite, and when this aqueous solution of calcium nitrite is added to concrete for reinforced concrete, it causes corrosion of reinforcing steel. . When an acid that forms a sparingly soluble calcium salt, such as sulfuric acid or phosphoric acid, is used instead of nitric acid, precipitation of calcium sulfate, calcium phosphate, and the like easily occurs in the aqueous solution of calcium nitrite due to the addition of the acid. This precipitate can be removed by filtration, but requires a filtration step. Also, organic acids are expensive. Therefore, nitric acid is preferred.
けれども、濃度の高い硝酸を亜硝酸カルシウム水溶液
に加えると、亜硝酸カルシウムの分解が起って水溶液か
ら窒素酸化物ガスが発生する。反対に薄すぎる硝酸を用
いると、亜硝酸カルシウム水溶液の濃度低下が起る。特
に好ましい硝酸として15〜45重量％の硝酸水溶液を用い
て、亜硝酸カルシウム水溶液の攪拌下にこれを添加する
と、このような問題が全く生起しない。However, when nitric acid with a high concentration is added to the aqueous solution of calcium nitrite, decomposition of calcium nitrite occurs and nitrogen oxide gas is generated from the aqueous solution. Conversely, if nitric acid that is too thin is used, the concentration of the aqueous solution of calcium nitrite will decrease. Such a problem does not occur at all when a nitric acid aqueous solution of 15 to 45% by weight is added as a particularly preferred nitric acid and the nitric acid aqueous solution is added with stirring.
20〜40重量％の亜硝酸カルシウム水溶液中の水酸化カ
ルシウム量を0.08重量％以下、好ましくは0.06〜0.02重
量％とすることにより、この水溶液は、残存水酸化カル
シウムによってアルカリ性に保たれ、低温でも塩基性亜
硝酸カルシウムを晶出しない。By setting the amount of calcium hydroxide in the aqueous solution of calcium nitrite of 20 to 40% by weight to 0.08% by weight or less, preferably 0.06 to 0.02% by weight, the aqueous solution is kept alkaline by the residual calcium hydroxide, and even at a low temperature. Does not crystallize basic calcium nitrite.
（実施例） 消石灰の30重量％水性スラリーに、NO/NO2モル比1.8
であるアンモニアを空気酸化したガスを、懸濁消石灰濃
度2.0重量％となるまで吸収させた後、この残存した懸
濁消石灰を濾別して除くことにより、透明な亜硝酸カル
シウム水溶液を得た。(Example) A 30% by weight aqueous slurry of slaked lime was mixed with a NO / NO 2 molar ratio of 1.8.
Was absorbed until the suspended slaked lime concentration became 2.0% by weight, and the remaining suspended slaked lime was removed by filtration to obtain a transparent calcium nitrite aqueous solution.
実施例１ 上記水溶液は、30重量％の亜硝酸カルシウムと0.12重
量％の水酸化カルシウムを含有しており、６℃まで冷却
したところ、結晶析出を起したが、この水溶液に攪拌下
30重量％の硝酸水溶液を加えて水酸化カルシウム濃度を
0.04重量％にしたところ、−５℃でも結晶析出が起らな
かった。Example 1 The above aqueous solution contained 30% by weight of calcium nitrite and 0.12% by weight of calcium hydroxide, and when cooled to 6 ° C, crystals precipitated.
Add 30% by weight aqueous nitric acid solution to reduce the concentration of calcium hydroxide
When the content was adjusted to 0.04% by weight, no crystal precipitation occurred even at -5 ° C.
実施例２ 34.1重量％の亜硝酸カルシウムと0.11重量％の水酸化
カルシウムを含有し、かつpH10.8である亜硝酸カルシウ
ム水溶液50kgを、循環ポンプを備えた容器中に投入し、
ポンプを作動させることにより５／分の速さで水溶液
を循環させた。次いで、このポンプのサクション側のパ
イプ中に、45重量％の硝酸水溶液130gを５分を要して注
入し、その後更に５分間ポンプ作動を続けた後ポンプを
停止させた。亜硝酸カルシウム水溶液のpHは10.4であ
り、そして分析したところ、亜硝酸カルシウム濃度は3
4.05重量％であり、水酸化カルシウム濃度は0.04重量％
であった。Example 2 50 kg of an aqueous solution of calcium nitrite containing 34.1% by weight of calcium nitrite and 0.11% by weight of calcium hydroxide and having a pH of 10.8 was charged into a vessel equipped with a circulation pump,
The aqueous solution was circulated at a rate of 5 / min by operating the pump. Next, 130 g of a 45% by weight aqueous nitric acid solution was injected into the pipe on the suction side of the pump in 5 minutes, and the pump operation was continued for another 5 minutes, and then the pump was stopped. The pH of the aqueous calcium nitrite solution was 10.4 and, when analyzed, the calcium nitrite concentration was 3
4.05% by weight, calcium hydroxide concentration 0.04% by weight
Met.
この得られた亜硝酸カルシウム水溶液を、１のポリ
エチレン製びんと１のガラス製びんの夫々に充填し、
密閉下３〜４℃で10日間保存したが、透明であり、結晶
の析出は全く起っていなかった。The obtained aqueous solution of calcium nitrite is filled in each of 1 polyethylene bottle and 1 glass bottle,
It was stored at 3-4 ° C. for 10 days in a sealed state, but it was transparent and no precipitation of crystals had occurred.
比較例１ 実施例２に用いられた硝酸添加前の亜硝酸カルシウム
水溶液をそのまま、実施例２と同様にして３〜４℃で10
日間保存したところ、１の液中にみかけ容積約100ml
の結晶析出が起っていた。Comparative Example 1 The aqueous solution of calcium nitrite before the addition of nitric acid used in Example 2 was directly used at 3 to 4 ° C. in the same manner as in Example 2.
When stored for one day, the apparent volume in one liquid is about 100 ml.
Crystal precipitation occurred.
実施例３ 34.3重量％の亜硝酸カルシウムと0.14重量％の水酸化
カルシウムを含有する水溶液2kgをビーカーに注入し、
攪拌下これに60重量％の硝酸水溶液6gを滴下したこと
ろ、この滴下部分の液面から窒素酸化物ガスの発生が起
った。Example 3 2 kg of an aqueous solution containing 34.3% by weight of calcium nitrite and 0.14% by weight of calcium hydroxide was poured into a beaker,
When 6 g of a 60% by weight nitric acid aqueous solution was dropped into this under stirring, nitrogen oxide gas was generated from the liquid level at the dropped portion.
今度は、実施例２で用いられた循環ポンプ付容器中で
テストした。20kgの上記亜硝酸カルシウム水溶液に、実
施例２と同様にしてポンプのサクション側に60重量％の
硝酸水溶液60gを３分を要して加えたところ、この硝酸
注入部分のパイプの温度が上昇し、ポンプにキャビテー
ションが起った。そして循環液の戻り側付近に酸化窒素
ガスの発生を認めた。10分経過後の液について分析した
ところ、亜硝酸カルシウム濃度が34.1重量％であり、水
酸化カルシウムの濃度は0.09重量％であった。この値に
基いて計算すると、加えた硝酸のうちその47％のみが水
酸化カルシウムと反応したことになる。This time, the test was performed in the container with a circulation pump used in Example 2. To 20 kg of the above aqueous solution of calcium nitrite, 60 g of a 60% by weight aqueous solution of nitric acid was added to the suction side of the pump in 3 minutes in the same manner as in Example 2, and the temperature of the pipe at the nitric acid injection portion rose. Cavitation occurred in the pump. Then, generation of nitric oxide gas was observed near the return side of the circulating liquid. Analysis of the liquid after 10 minutes showed that the concentration of calcium nitrite was 34.1% by weight and the concentration of calcium hydroxide was 0.09% by weight. Calculating based on this value, only 47% of the added nitric acid had reacted with calcium hydroxide.
この結果は、本発明を好ましく実施するには、加える
硝酸として60重量％水溶液ではやゝその濃度が高すぎる
ことを示している。This result indicates that the concentration of nitric acid added in a 60% by weight aqueous solution is too high for the preferred practice of the present invention.
今度は、上記60重量％の硝酸水溶液の代りに、５重量
％の硝酸水溶液を用いて、上記同様にして循環ポンプ付
容器中の亜硝酸カルシウム水溶液にポンプのサクション
側からこれを注入した。液のpHが10.4を示すまでに950g
の硝酸水溶液が加えられた。このテストでは、窒素酸化
物ガスの発生も、パイプの温度上昇も起らず、そして、
得られた液を３〜４℃で10日間保存しても結晶析出が起
らなかったが、分析したところ、亜硝酸カルシウム濃度
は32.7重量％であり、硝酸と一緒に加わった水によって
亜硝酸カルシウム水溶液は薄まったことが認められる。This time, instead of the 60% by weight aqueous nitric acid solution, a 5% by weight aqueous solution of nitric acid was used to inject the aqueous solution of calcium nitrite in the container with a circulation pump from the suction side of the pump in the same manner as described above. 950 g until the pH of the solution shows 10.4
Of nitric acid was added. In this test, neither nitrogen oxide gas was generated nor the pipe temperature increased, and
Crystals did not precipitate even when the obtained liquid was stored at 3 to 4 ° C. for 10 days. However, when analyzed, the calcium nitrite concentration was 32.7% by weight, and water added together with nitric acid caused It is observed that the calcium aqueous solution has diluted.
この結果は、本発明は好ましく実施するには、加える
硝酸として５重量％の水溶液ではその濃度が薄すぎるこ
とを示している。The results show that the 5% by weight aqueous solution of nitric acid as added nitric acid is too thin for the preferred implementation of the invention.
（発明の効果） 本発明によると、低温において結晶析出を起さない20
〜40重量％の亜硝酸カルシウム水溶液を簡易かつ効率よ
くつくることができる。特に、消石灰の水性スラリーに
NO/NO2モル比１以上の酸化窒素含有ガスを吸収させた後
残存する懸濁消石灰を濾別することにより得られる20〜
40重量％の亜硝酸カルシウム水溶液から、低温で結晶析
出を起さないほぼ同濃度の亜硝酸カルシウム水溶液を簡
易につくることができる。本発明の方法は安定な亜硝酸
カルシウム水溶液の工業生産方法として有用である。(Effect of the Invention) According to the present invention, no crystal precipitation occurs at low temperatures.
An aqueous solution of about 40% by weight of calcium nitrite can be easily and efficiently produced. Especially for aqueous slurry of slaked lime
20 to 20 obtained by filtering the remaining suspended slaked lime after absorbing a nitrogen oxide-containing gas having a NO / NO 2 molar ratio of 1 or more.
From a 40% by weight aqueous solution of calcium nitrite, an aqueous solution of calcium nitrite having substantially the same concentration without causing crystal precipitation at low temperatures can be easily prepared. The method of the present invention is useful as a method for industrially producing a stable aqueous solution of calcium nitrite.
硝酸添加によって水酸化カルシウム含有率0.08〜0.02
重量％に調製された20〜40重量％の亜硝酸カルシウム水
溶液は、従来と同様にコンクリート添加剤、防錆剤、防
凍剤等として用いることができる。Calcium hydroxide content 0.08 to 0.02 by adding nitric acid
The aqueous solution of 20 to 40% by weight of calcium nitrite adjusted to the percentage by weight can be used as a concrete additive, a rust preventive, a deicing agent and the like as in the prior art.
Claims (2)
O）と二酸化窒素（NO2）をNO/NO2モル比１以上の比率に
含有するガスを吸収反応させた後、残存する懸濁消石灰
を該スラリーから濾別することにより得られる生成亜硝
酸カルシウム濃度20〜40重量％の水溶液の安定化方法に
おいて、該水溶液に硝酸を加えることにより、該水溶液
中の水酸化カルシウム量を0.08〜0.02重量％とすること
を特徴とする亜硝酸カルシウム水溶液の安定化方法。1. An aqueous slurry of slaked lime is mixed with nitric oxide (N
O) and a gas containing nitrogen dioxide (NO 2 ) in a NO / NO 2 molar ratio of 1 or more are caused to undergo an absorption reaction, and then the remaining suspended slaked lime is filtered from the slurry to produce nitrous acid. A method for stabilizing an aqueous solution having a calcium concentration of 20 to 40% by weight, wherein nitric acid is added to the aqueous solution to adjust the amount of calcium hydroxide in the aqueous solution to 0.08 to 0.02% by weight. Stabilization method.
が、その添加によって亜硝酸カルシウム水溶液中の水酸
化カルシウム量が0.06〜0.02重量％となる量の10〜55重
量％水溶液の硝酸であることを特徴とする第（１）請求
項に記載の亜硝酸カルシウム水溶液の安定化方法。2. The nitric acid added in the first aspect is a 10-55% by weight aqueous solution of nitric acid in which the amount of calcium hydroxide in the aqueous solution of calcium nitrite becomes 0.06-0.02% by weight. The method for stabilizing an aqueous solution of calcium nitrite according to claim 1, wherein:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7576088A JP2629252B2 (en) | 1988-03-29 | 1988-03-29 | Stabilization method of calcium nitrite aqueous solution |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7576088A JP2629252B2 (en) | 1988-03-29 | 1988-03-29 | Stabilization method of calcium nitrite aqueous solution |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01246114A JPH01246114A (en) | 1989-10-02 |
| JP2629252B2 true JP2629252B2 (en) | 1997-07-09 |
Family
ID=13585505
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7576088A Expired - Lifetime JP2629252B2 (en) | 1988-03-29 | 1988-03-29 | Stabilization method of calcium nitrite aqueous solution |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2629252B2 (en) |
-
1988
- 1988-03-29 JP JP7576088A patent/JP2629252B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01246114A (en) | 1989-10-02 |
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