CA1106136A - Process for producing sodium percarbonate from a soda solution of suspension - Google Patents
Process for producing sodium percarbonate from a soda solution of suspensionInfo
- Publication number
- CA1106136A CA1106136A CA315,322A CA315322A CA1106136A CA 1106136 A CA1106136 A CA 1106136A CA 315322 A CA315322 A CA 315322A CA 1106136 A CA1106136 A CA 1106136A
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- Canada
- Prior art keywords
- sodium
- solution
- percarbonate
- soda
- phosphate
- Prior art date
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-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B15/00—Peroxides; Peroxyhydrates; Peroxyacids or salts thereof; Superoxides; Ozonides
- C01B15/055—Peroxyhydrates; Peroxyacids or salts thereof
- C01B15/10—Peroxyhydrates; Peroxyacids or salts thereof containing carbon
- C01B15/103—Peroxyhydrates; Peroxyacids or salts thereof containing carbon containing only alkali metals as metals
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Detergent Compositions (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
.
The present invention provides in a process for producing a compact coarse sodium percarbonate by reacting hydrogen percarbonate with sodium carbonate at 10 to 20°C, starting with a solution which contains sodium carbonate and is saturated with sodium percarbonate, in the presence of 100 to 200 g of sodium chloride per litre of solution, stabilizers of active oxygen, and sodium hexameta-phosphate, the improvement in which is said solution, which contains 0.1 to 1.9 g of sodium hexameta-phosphate per litre of solution, the ratio of soda to sodium hexameta-phosphate is adjusted to a value from 65:1 to 500:1, and the soda solution or suspension thus produced is mixed with an amount of hydrogen peroxide which is practically equivalent to the amount of sodium carbonate dissolved or suspen-ded or both, in the starting solution while maintaining approximately a constant same temperature during the entire pre-cipitation, and during and after the addition of hydrogen peroxide up to 60 minutes after this addition the resulting supersaturation with dissolved sodium percarbonate is reduced by precipitating the sodium percarbonate, the salt obtained is separated and dried.
.
The present invention provides in a process for producing a compact coarse sodium percarbonate by reacting hydrogen percarbonate with sodium carbonate at 10 to 20°C, starting with a solution which contains sodium carbonate and is saturated with sodium percarbonate, in the presence of 100 to 200 g of sodium chloride per litre of solution, stabilizers of active oxygen, and sodium hexameta-phosphate, the improvement in which is said solution, which contains 0.1 to 1.9 g of sodium hexameta-phosphate per litre of solution, the ratio of soda to sodium hexameta-phosphate is adjusted to a value from 65:1 to 500:1, and the soda solution or suspension thus produced is mixed with an amount of hydrogen peroxide which is practically equivalent to the amount of sodium carbonate dissolved or suspen-ded or both, in the starting solution while maintaining approximately a constant same temperature during the entire pre-cipitation, and during and after the addition of hydrogen peroxide up to 60 minutes after this addition the resulting supersaturation with dissolved sodium percarbonate is reduced by precipitating the sodium percarbonate, the salt obtained is separated and dried.
Description
~1~613~i The present inven~ion relates to a process for pro-ducing sodium percar~onate from a soda solution or suspension.
_ The production of sodium percarbonate by reacting a soda solution or suspension with aqueous hydrogen peroxide solutions according to the formula.
' Na2 CO3 + 1.5 H22 > Na2 CO3 1.5 H22 ¦ while reducing the solubility of the percarbonate thus formed by adding inert salts such as sodium chloride is disclosed in Swiss Patent No. 90295.
~! lo In Brazilian Patent No. 568754 the continuous produc-tion of sodium percarbonate from hydrogen peroxide and sodium carbonate is described, the required amounts of hydrogen perox-ide and sodium carbonate being added only in small portions.
Ths use of stabilizers for active oxygen, as for example, --, magnesium compounds, and the favourable effect of hexameta-; phosphate on the granular structure of the percarbonate are also mentioned.
The disadvantage of this process is that, as mentioned hereinbefore, the soda and hydrogen peroxide are added only in small amounts and reaction times must be allowed between the additions. During the additions the temperature increases from 15 to 22C. This temperature is maintained to the end of the reaction. This method results in a fine, sprouting percarbonate.
Moreover, according to laid-open German Specification No. 2,328,803 an abrasion-resistant, coarse percarbonate can be produced by reacting a soda solution or suspension, which con-tains from 2 to 8 g of sodium hexameta-phosphate per litre of solution with a hydrogen peroxide solution, which contains from 3 to 10 g of magnesium ions per litre of solution, if required ¦ 30 in the presence of sodium chloride~ Great importance is attached to maintaining exactly the amounts of sodium hexameta-phosphate .
and magnesium ions. Otherwise, fine or non-resistant particles -1- ~
are obtained. ~he disadvantage of this process which is oper-ated only discontinuously is that on reusing the mother liquor at the elevated temperature of 24~C the yield of hydrogen per-oxide is greatly reduced by the decomposition of active oxygen.
On using technical soda the decomposition is even intensified by the concentration of the impurities. Because of this decompo-sition of active oxygen which continues ashydrogen peroxide is added the conditions for the crystallization of the sodium percarbonate cannot be kept constant. The ratio of soda to sodium percarbonate shifts in favour of soda which, as the more easily soluble component, exerts additional pressure on the sodium percarbonate still in solution. The resulting crystall-ization is too rapid and a fine-grained product is obtained.
Moveover, as described in U.S. Patent No. 4,118,466 issued October 3, 1978, specific amounts of sodium hexameta-phosphate are required on using a solution saturated with sodium carbonate. If the amount of sodium hexameta-phosphate is too high, then the supersaturation of the sodium percarbonate being formed is too stable and cannot be reduced at all or only partially. If the amount of sodium hexameta-phosphate is too small, then the resulting supersaturation of percarbonate is too low and the product obtained is too fine. Thus, it is important that at a predetermined amount of soda to be reacted, at constant concentration of the solution components still present and at the reaction temperature a specific ratio of rate of soda reaction to the dissolved amount of sodium hexameta-phosphate is chosen.
According to the process of the U.S. Patent this was possible only to the solubility of the soda.
The present invention provides a technically simpler manner of carrying out the process of U.S. Patent No. 4,118,466 issued October 3,1978, which, produced in an absolutely reliable ~1~E613~
reproduci~le manner the coarse compact particles at 10 to 20C., as well as an increase in the rate of reaction of the soda.
According to the present invention there is provided in a process for producing a compact coarse sodium percarbonate by reacting hydrogen per'oxide'with s'odium carbonate at 10 to 20C, starting with a solution which contains sodium carbonate and is saturated with sodium percarbonate, in the presence of 100 to 200 g of sodium chloride per litre of solution, stabilizers of active oxygen, and sodium hexameta-phosphate, the improvement in which in said solution, which contains 0.1 to 1.9 g o~ sodium hexameta-phosphate per litre of solution, the ratio of soda to sodium hexameta-phosphate is adjusted to a value from 65:1 to 500:1, and the soda solution or suspension thus produced is mixed with an amount of hydrogen peroxide which is practically equi-valent to the amount of sodium carbonate dissolved or sus-pended or both in the starting solution while maintaining ~:
approximately a constant same temperature during the entire precipitation, and during and after the addition of hydrogen peroxide up to 60 minutes after this addition the resulting supersaturation with dissolved sodium percarbonate is reduced by precipitating'the sodium percarbonate, the salt obtained is separated and dried.
Thus according to the present invention in the reaction of sodium carbonate with hydrogen peroxide, starting with a '~ sodium-carbonate-containing solution, which is saturated with sodium percarbonate, in the presence of 100 to 200 g sodium chloride per litre of solution, conventional active-oxygen stabili~ers and sodium hexameta-phosphate at 10 to 20C, such a solution which contains 0.1 to 1.9 g of sodium hexameta-phosphate X - 2a -1~6136 per litre has the ratio of soda to sodium hexameta-phosphate adjusted to a value from 65:1 to 500:1 and the soda solution or -~ suspension is mixed with an amount of hydrogen peroxide which is r practically equivalent to the amount of sodium carbonate dis-: .~
~7 .
` '' .~ ' ',.
, .~ .
J
6~36 solved or suspended or both, in the starting solution while maintainin~ approximately the same temperature,during the entire _ precipitation, and during and after the addition of hydrogen peroxide up to 60 minutes after this addition~the resulting supersaturation with dissolved sodium percarbonate is reduced ~ by precipitating the sodium percarbonate, the salt obtained is ¦ separated by means of conventional methods and dried and, when ~ required, the mother liquor so obtained is returned to the -~ operating stage for the soda solution applied.
¦ 10 In order to keep the loss of active oxygen as low as possible the process is not carried out at temperatures above 20C. The temperature is preferably kept at 14 to 16C.
The types of soda applied are calcined soda, soda p.a.
as well as technical soda.
....
It has now been found that at constant concentrations of the dissolved components present in addition to soda and at constant reaction temperature a specific ratio of the rate of -; soda reaction to the amount of dissolved sodium hexameta-phos-phate must be maintained for a controlled increase and decrease ~ 20 of the supersaturation with sodium percarbonate during and ¦ after the addition of hydrogen proxide and lastly also for a coarse compact product.
The following procedure is used to determine the correct ratio of soda reaction rate to sodium hexameta-phosphate.
After fixing the reaction temperature to a value between +10C
and 20C, the amount of sodium chloride in solution to a value between 100 g per litre and 200 g per litre and the nearly constant contents of approximately 4.5 g of Mg SO4.7H2O per litre and approximately 0.1 g of sodium hexameta-phosphate per 3~ litre this solution is almost saturated by dissolving 51 g of sodium carbonate and adding 30 ml of a 70% by weight hydrogen peroxide. Approximately 75 g of sodium percarbonate are thus llQ6:13~
formed per litre. In this percarbonate mother liquor the correct ratio of rate of soda reaction to sodium hexameta-phosphate at which a coarse compact product is obtained by a controlled increase and decrease of the supersaturation with sodium percarbonate must then be determined by a series of pre-liminary tests. Thus, for example, at +10C in a saturated sodium percarbonate solution in the presence of 200 g of sodium chloride per litre, 4.5 g of MgSO4.7H2O per litre and 0.1 g of sodium hexameta-phosphate per litre the ratio of Na2CO3:(NaPO3)6 had to be adjusted to 500:1 in order to obtain a coarse compact percarbonate. At +20C in a saturated sodium percarbonate solution in the presence of 100 g of sodium chloride per litre, - 4.5 g of MgS04.7H2O per litre and 1.9 g of sodium hexameta-~k phosphate per litre the ratio of Na2CO3:(NaPO3)6 had to be 110:1 in order to obtain a coarse compact product.
In order to avoid losses of active oxygen, the entire ~ precipitation process is carried out below 20C at approximately A~, one and the same temperature, i.e., at - 1C with respect to the temperature chosen.
As mentioned hereinbefore, the amounts of hydrogen peroxide added must be approximately equivalent to the amount of sodium percarbonate present (see the aforesaidformula). By"approxim-ately equivaIent" a ratio of active oxygen to sodium of 0.6 to 0.9 to 1 is meant. Particularly 70% by weight aqueous solutions _ are suitable as hydrogen peroxide solutions. However, higher-percentage commercial aqueous hydrogen peroxide solutions can also be used. Solutions having concentrations lower than 70%
by weight are also suitable. However, as the hydrogen peroxide concentration decreases the amount of water fed to the system ; 30 increases, whereby the pressure of crystallization for percar-bonate decreases on the one hand and the excess of mother liquor ~, increases on the other.
:, ~' .
In the process the usual stabilizers of active oxygen, ~ such as magnesium salts and alkali metal salts, preferably mag-- nesium sulphate, are used The stabilizers are added to the ~ aqueous hydrogen peroxide solution.
~4 At the start of the process according to the invention the mother liquor consisting of 40 to 100 g of sodium percarbon-ate, 0.1 to 1.9 g of sodium hexameta-phosphate, 100 to 200 g of sodium chloride, relative to 1 litre of solution, and saturated -I with basic magnesium carbonate and magnesium silicate is produced synthetically as an aqueous solution.
This synthetic mother liquor serves for producing the soda solution or suspension. Said solution can also be ` ~ produced with the mother liquor obtained after separating the sodium percarbonate formed. The latter mother liquor also -contains 40 to 100 g of sodium percarbonate per litre. However, this mother liquor must then be adjusted to the concentrations of sodium hexameta-phosphate and sodium chloride mentioned -~ heretofore.
When using sodium tetrasilicate and reusing the mother liquor saturated with sodium percarbonate which still ~ contains a portion of the stabilizers of the preceding charge it q is favourable to filter the mother liquor in order to separate the precipitated maynesium silicate prior to applying the calcined soda. The magnesium concentration decreases at the same time. Therefore, it varies only slightly in this solution.
The supersaturation is increased and decreased while stirring. It is a known fact that the rate of nuclei formation depends on the rate of stirring. ~7hen stirring rapidly the supersaturation is reduced too fast and the produc~ obtained is J 30 too fine. However, when stirring too slowly the decrease of the supersaturation is incomplete. If the mother liquor from .ç~ .
this kind of charge is used for the production of the soda , , - :, 11(1~i136 solution, then the sodium percarbonate crystallizes even during the production of this solution since the more easily soluble soda precipitates the moredifficultly soluble sodium percarbonate out of the solution. This sodium percarbonate then is precip-~, ricated along with the impurities and thus is lost. In order ~ to determine the optimum rate of stirring, the supersaturation ¦ with sodium percarbonate immediately after the addition of the hydrogen peroxide is determined, where upon its reduction is determined. The chosen rate of stirriny is finally determined by the quality of the salt obtained, i.e., by the coarse compact ¦ particle. If the supersaturation is reduced too rapidly, then the rate of stirring must be decreased and vice versa until the j desired rate of reduction is obtained.
The same applies to the rate of dosing the hydrogenperoxide solution to the soda solution. This rate of dosing can be determined for the operation in a laboratory test. The ~ optimum rates of dosing required for reacting the required -~ amounts are from 10 to 20 minutes.
~;
The precipitated sodium percarbonate is filtered off and dried in a conventional manner. The process can be carried out without difficulties in conventional plants for the produc-tion of sodium percarbonate.
_ The advance in the art of the process lies in the reuse of the mother liquor while the crystallization parameters, such as composition of the soda solution applied are largely constant, an approximately invariable degree of impurity, the temperature and in the very simple technical manner of carrying .~
out the process.
. A qualitatively homogeneous, i.e., a coarse compact product is thus obtained after each reaction.
The present invention is further illustrated by the `~ following Examples:
11~613~
NaPc represents sodium percarbonate Hexa represents sodium hexameta-phosphate ~ Oa represents active oxygen g-At/l represents gram atom per litre.
I
_perational Test_- Example 1 cu m of NaPc liquor of 15C, which contains 200 g of NaCl, 72-2 g of Na2CO3-1.5 H2O2, 4.5 g of MgSO4.7H2O and 0.15 g of Hexa per litre, is put into a V4V tank (diameter =
1530 mm, height = 1420 mm) while stirring (diameter of the stirrer propeller = 500 mm, rate of stirring = 200 r.p.m.) 1.35 kg of Hexa are dissolved in this liquor. At constant temp-I erature (15~C) and while stirring, 105 kg of technical calcined ".
96% soda are then added over 25 minutes by way of an AEG weight feeder.
Immediately upon completed addition of soda 76 litres of H2O2 solution (23.7 moles per litre) containing 52.6 g of MgSO4.7H2O and 65.8 g of NaCl are added by way of a rotameter.
Afterthe addition of the H2O2 solution 142 g of NaPc per litre were in solution which were reduced to 71.4 g per litre within 45 minutes.
Past-reaction Liquor analysis r~ time I min. Na Oa Oa/Na NaPc g~t/l g~t/l ratio dissolved After addition 0 1.81 1.43 0.79 142.0 f H22 _ _ _ _ _ _ 0.91 0.79 0.87 71.4 The salt mash was separated from the mother liquor by way of a continuously operating centrifuge and the salt was dried in a fluidized bed dryer.
150 kg of finished product having the following anal-U6~36 analytical data were obtained:Active oxygen: 13,94%
- powder density: 941 g per litre ~ sieve analysis .... .
for 0.8 mm: 6%
for 0.5 mm: 29%
for 0.4 mm: 15%
for 0.2 mm: 38%
for 0.1 mm: 12%
10rest: 0%
' .
: ~, ..
, 20 , ~ , ~
:
;'.` .
:' j .'';~
, .~, .
~ 30 ~ .
`'~ .
--8-- .
_ The production of sodium percarbonate by reacting a soda solution or suspension with aqueous hydrogen peroxide solutions according to the formula.
' Na2 CO3 + 1.5 H22 > Na2 CO3 1.5 H22 ¦ while reducing the solubility of the percarbonate thus formed by adding inert salts such as sodium chloride is disclosed in Swiss Patent No. 90295.
~! lo In Brazilian Patent No. 568754 the continuous produc-tion of sodium percarbonate from hydrogen peroxide and sodium carbonate is described, the required amounts of hydrogen perox-ide and sodium carbonate being added only in small portions.
Ths use of stabilizers for active oxygen, as for example, --, magnesium compounds, and the favourable effect of hexameta-; phosphate on the granular structure of the percarbonate are also mentioned.
The disadvantage of this process is that, as mentioned hereinbefore, the soda and hydrogen peroxide are added only in small amounts and reaction times must be allowed between the additions. During the additions the temperature increases from 15 to 22C. This temperature is maintained to the end of the reaction. This method results in a fine, sprouting percarbonate.
Moreover, according to laid-open German Specification No. 2,328,803 an abrasion-resistant, coarse percarbonate can be produced by reacting a soda solution or suspension, which con-tains from 2 to 8 g of sodium hexameta-phosphate per litre of solution with a hydrogen peroxide solution, which contains from 3 to 10 g of magnesium ions per litre of solution, if required ¦ 30 in the presence of sodium chloride~ Great importance is attached to maintaining exactly the amounts of sodium hexameta-phosphate .
and magnesium ions. Otherwise, fine or non-resistant particles -1- ~
are obtained. ~he disadvantage of this process which is oper-ated only discontinuously is that on reusing the mother liquor at the elevated temperature of 24~C the yield of hydrogen per-oxide is greatly reduced by the decomposition of active oxygen.
On using technical soda the decomposition is even intensified by the concentration of the impurities. Because of this decompo-sition of active oxygen which continues ashydrogen peroxide is added the conditions for the crystallization of the sodium percarbonate cannot be kept constant. The ratio of soda to sodium percarbonate shifts in favour of soda which, as the more easily soluble component, exerts additional pressure on the sodium percarbonate still in solution. The resulting crystall-ization is too rapid and a fine-grained product is obtained.
Moveover, as described in U.S. Patent No. 4,118,466 issued October 3, 1978, specific amounts of sodium hexameta-phosphate are required on using a solution saturated with sodium carbonate. If the amount of sodium hexameta-phosphate is too high, then the supersaturation of the sodium percarbonate being formed is too stable and cannot be reduced at all or only partially. If the amount of sodium hexameta-phosphate is too small, then the resulting supersaturation of percarbonate is too low and the product obtained is too fine. Thus, it is important that at a predetermined amount of soda to be reacted, at constant concentration of the solution components still present and at the reaction temperature a specific ratio of rate of soda reaction to the dissolved amount of sodium hexameta-phosphate is chosen.
According to the process of the U.S. Patent this was possible only to the solubility of the soda.
The present invention provides a technically simpler manner of carrying out the process of U.S. Patent No. 4,118,466 issued October 3,1978, which, produced in an absolutely reliable ~1~E613~
reproduci~le manner the coarse compact particles at 10 to 20C., as well as an increase in the rate of reaction of the soda.
According to the present invention there is provided in a process for producing a compact coarse sodium percarbonate by reacting hydrogen per'oxide'with s'odium carbonate at 10 to 20C, starting with a solution which contains sodium carbonate and is saturated with sodium percarbonate, in the presence of 100 to 200 g of sodium chloride per litre of solution, stabilizers of active oxygen, and sodium hexameta-phosphate, the improvement in which in said solution, which contains 0.1 to 1.9 g o~ sodium hexameta-phosphate per litre of solution, the ratio of soda to sodium hexameta-phosphate is adjusted to a value from 65:1 to 500:1, and the soda solution or suspension thus produced is mixed with an amount of hydrogen peroxide which is practically equi-valent to the amount of sodium carbonate dissolved or sus-pended or both in the starting solution while maintaining ~:
approximately a constant same temperature during the entire precipitation, and during and after the addition of hydrogen peroxide up to 60 minutes after this addition the resulting supersaturation with dissolved sodium percarbonate is reduced by precipitating'the sodium percarbonate, the salt obtained is separated and dried.
Thus according to the present invention in the reaction of sodium carbonate with hydrogen peroxide, starting with a '~ sodium-carbonate-containing solution, which is saturated with sodium percarbonate, in the presence of 100 to 200 g sodium chloride per litre of solution, conventional active-oxygen stabili~ers and sodium hexameta-phosphate at 10 to 20C, such a solution which contains 0.1 to 1.9 g of sodium hexameta-phosphate X - 2a -1~6136 per litre has the ratio of soda to sodium hexameta-phosphate adjusted to a value from 65:1 to 500:1 and the soda solution or -~ suspension is mixed with an amount of hydrogen peroxide which is r practically equivalent to the amount of sodium carbonate dis-: .~
~7 .
` '' .~ ' ',.
, .~ .
J
6~36 solved or suspended or both, in the starting solution while maintainin~ approximately the same temperature,during the entire _ precipitation, and during and after the addition of hydrogen peroxide up to 60 minutes after this addition~the resulting supersaturation with dissolved sodium percarbonate is reduced ~ by precipitating the sodium percarbonate, the salt obtained is ¦ separated by means of conventional methods and dried and, when ~ required, the mother liquor so obtained is returned to the -~ operating stage for the soda solution applied.
¦ 10 In order to keep the loss of active oxygen as low as possible the process is not carried out at temperatures above 20C. The temperature is preferably kept at 14 to 16C.
The types of soda applied are calcined soda, soda p.a.
as well as technical soda.
....
It has now been found that at constant concentrations of the dissolved components present in addition to soda and at constant reaction temperature a specific ratio of the rate of -; soda reaction to the amount of dissolved sodium hexameta-phos-phate must be maintained for a controlled increase and decrease ~ 20 of the supersaturation with sodium percarbonate during and ¦ after the addition of hydrogen proxide and lastly also for a coarse compact product.
The following procedure is used to determine the correct ratio of soda reaction rate to sodium hexameta-phosphate.
After fixing the reaction temperature to a value between +10C
and 20C, the amount of sodium chloride in solution to a value between 100 g per litre and 200 g per litre and the nearly constant contents of approximately 4.5 g of Mg SO4.7H2O per litre and approximately 0.1 g of sodium hexameta-phosphate per 3~ litre this solution is almost saturated by dissolving 51 g of sodium carbonate and adding 30 ml of a 70% by weight hydrogen peroxide. Approximately 75 g of sodium percarbonate are thus llQ6:13~
formed per litre. In this percarbonate mother liquor the correct ratio of rate of soda reaction to sodium hexameta-phosphate at which a coarse compact product is obtained by a controlled increase and decrease of the supersaturation with sodium percarbonate must then be determined by a series of pre-liminary tests. Thus, for example, at +10C in a saturated sodium percarbonate solution in the presence of 200 g of sodium chloride per litre, 4.5 g of MgSO4.7H2O per litre and 0.1 g of sodium hexameta-phosphate per litre the ratio of Na2CO3:(NaPO3)6 had to be adjusted to 500:1 in order to obtain a coarse compact percarbonate. At +20C in a saturated sodium percarbonate solution in the presence of 100 g of sodium chloride per litre, - 4.5 g of MgS04.7H2O per litre and 1.9 g of sodium hexameta-~k phosphate per litre the ratio of Na2CO3:(NaPO3)6 had to be 110:1 in order to obtain a coarse compact product.
In order to avoid losses of active oxygen, the entire ~ precipitation process is carried out below 20C at approximately A~, one and the same temperature, i.e., at - 1C with respect to the temperature chosen.
As mentioned hereinbefore, the amounts of hydrogen peroxide added must be approximately equivalent to the amount of sodium percarbonate present (see the aforesaidformula). By"approxim-ately equivaIent" a ratio of active oxygen to sodium of 0.6 to 0.9 to 1 is meant. Particularly 70% by weight aqueous solutions _ are suitable as hydrogen peroxide solutions. However, higher-percentage commercial aqueous hydrogen peroxide solutions can also be used. Solutions having concentrations lower than 70%
by weight are also suitable. However, as the hydrogen peroxide concentration decreases the amount of water fed to the system ; 30 increases, whereby the pressure of crystallization for percar-bonate decreases on the one hand and the excess of mother liquor ~, increases on the other.
:, ~' .
In the process the usual stabilizers of active oxygen, ~ such as magnesium salts and alkali metal salts, preferably mag-- nesium sulphate, are used The stabilizers are added to the ~ aqueous hydrogen peroxide solution.
~4 At the start of the process according to the invention the mother liquor consisting of 40 to 100 g of sodium percarbon-ate, 0.1 to 1.9 g of sodium hexameta-phosphate, 100 to 200 g of sodium chloride, relative to 1 litre of solution, and saturated -I with basic magnesium carbonate and magnesium silicate is produced synthetically as an aqueous solution.
This synthetic mother liquor serves for producing the soda solution or suspension. Said solution can also be ` ~ produced with the mother liquor obtained after separating the sodium percarbonate formed. The latter mother liquor also -contains 40 to 100 g of sodium percarbonate per litre. However, this mother liquor must then be adjusted to the concentrations of sodium hexameta-phosphate and sodium chloride mentioned -~ heretofore.
When using sodium tetrasilicate and reusing the mother liquor saturated with sodium percarbonate which still ~ contains a portion of the stabilizers of the preceding charge it q is favourable to filter the mother liquor in order to separate the precipitated maynesium silicate prior to applying the calcined soda. The magnesium concentration decreases at the same time. Therefore, it varies only slightly in this solution.
The supersaturation is increased and decreased while stirring. It is a known fact that the rate of nuclei formation depends on the rate of stirring. ~7hen stirring rapidly the supersaturation is reduced too fast and the produc~ obtained is J 30 too fine. However, when stirring too slowly the decrease of the supersaturation is incomplete. If the mother liquor from .ç~ .
this kind of charge is used for the production of the soda , , - :, 11(1~i136 solution, then the sodium percarbonate crystallizes even during the production of this solution since the more easily soluble soda precipitates the moredifficultly soluble sodium percarbonate out of the solution. This sodium percarbonate then is precip-~, ricated along with the impurities and thus is lost. In order ~ to determine the optimum rate of stirring, the supersaturation ¦ with sodium percarbonate immediately after the addition of the hydrogen peroxide is determined, where upon its reduction is determined. The chosen rate of stirriny is finally determined by the quality of the salt obtained, i.e., by the coarse compact ¦ particle. If the supersaturation is reduced too rapidly, then the rate of stirring must be decreased and vice versa until the j desired rate of reduction is obtained.
The same applies to the rate of dosing the hydrogenperoxide solution to the soda solution. This rate of dosing can be determined for the operation in a laboratory test. The ~ optimum rates of dosing required for reacting the required -~ amounts are from 10 to 20 minutes.
~;
The precipitated sodium percarbonate is filtered off and dried in a conventional manner. The process can be carried out without difficulties in conventional plants for the produc-tion of sodium percarbonate.
_ The advance in the art of the process lies in the reuse of the mother liquor while the crystallization parameters, such as composition of the soda solution applied are largely constant, an approximately invariable degree of impurity, the temperature and in the very simple technical manner of carrying .~
out the process.
. A qualitatively homogeneous, i.e., a coarse compact product is thus obtained after each reaction.
The present invention is further illustrated by the `~ following Examples:
11~613~
NaPc represents sodium percarbonate Hexa represents sodium hexameta-phosphate ~ Oa represents active oxygen g-At/l represents gram atom per litre.
I
_perational Test_- Example 1 cu m of NaPc liquor of 15C, which contains 200 g of NaCl, 72-2 g of Na2CO3-1.5 H2O2, 4.5 g of MgSO4.7H2O and 0.15 g of Hexa per litre, is put into a V4V tank (diameter =
1530 mm, height = 1420 mm) while stirring (diameter of the stirrer propeller = 500 mm, rate of stirring = 200 r.p.m.) 1.35 kg of Hexa are dissolved in this liquor. At constant temp-I erature (15~C) and while stirring, 105 kg of technical calcined ".
96% soda are then added over 25 minutes by way of an AEG weight feeder.
Immediately upon completed addition of soda 76 litres of H2O2 solution (23.7 moles per litre) containing 52.6 g of MgSO4.7H2O and 65.8 g of NaCl are added by way of a rotameter.
Afterthe addition of the H2O2 solution 142 g of NaPc per litre were in solution which were reduced to 71.4 g per litre within 45 minutes.
Past-reaction Liquor analysis r~ time I min. Na Oa Oa/Na NaPc g~t/l g~t/l ratio dissolved After addition 0 1.81 1.43 0.79 142.0 f H22 _ _ _ _ _ _ 0.91 0.79 0.87 71.4 The salt mash was separated from the mother liquor by way of a continuously operating centrifuge and the salt was dried in a fluidized bed dryer.
150 kg of finished product having the following anal-U6~36 analytical data were obtained:Active oxygen: 13,94%
- powder density: 941 g per litre ~ sieve analysis .... .
for 0.8 mm: 6%
for 0.5 mm: 29%
for 0.4 mm: 15%
for 0.2 mm: 38%
for 0.1 mm: 12%
10rest: 0%
' .
: ~, ..
, 20 , ~ , ~
:
;'.` .
:' j .'';~
, .~, .
~ 30 ~ .
`'~ .
--8-- .
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a process for producing a compact coarse sodium percarbonate by reacting hydrogen percarbonate with sodium carbonate at 10 to 20°C, starting with a solution which contains sodium carbonate and is saturated with sodium percarbonate in the presence of 100 to 200 g of sodium chloride per litre of solu-tion, stabilizers of active oxygen, and sodium hexameta-phos-phate, the improvement in which is said solution, which contains 0:1 to 1.9 g of sodium hexameta-phosphate per litre of solution, the ratio of soda to sodium hexameta-phosphate is adjusted to a value from 65:1 to 500:1, and the soda solution or suspension thus produced is mixed with an amount of hydrogen peroxide which is practically equivalent to the amount of sodium carbonate dissolved or suspended or both, in the starting solution while maintaining approximately a constant same temperature during the entire precititation, and during and after the addition of hydrogen peroxide up to 60 minutes after this addition the resulting supersaturation with dissolved sodium percarbonate is reduced by precipitating the sodium percarbonate, the salt obtained is separated and dried.
2. A process as claimed in Claim 1, in which result-ant mother liquor is recycled for use as the initial soda solution.
3. A process according to Claim 1, in which the selected precipitation temperature varies by ? 1°C during the process.
4. A process as claimed in Claim 1, 2 or 3, in which the temperature is below 20°C.
5. A process as claimed in Claim 1, 2 or 3, in which the temperature is from 14 to 16°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2800760.5 | 1978-01-09 | ||
| DE2800760A DE2800760C2 (en) | 1978-01-09 | 1978-01-09 | Process for the production of sodium percarbonate from a soda solution or suspension |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1106136A true CA1106136A (en) | 1981-08-04 |
Family
ID=6029185
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA315,322A Expired CA1106136A (en) | 1978-01-09 | 1978-10-31 | Process for producing sodium percarbonate from a soda solution of suspension |
Country Status (17)
| Country | Link |
|---|---|
| JP (1) | JPS54101798A (en) |
| AT (1) | AT386590B (en) |
| BE (1) | BE873347A (en) |
| CA (1) | CA1106136A (en) |
| CH (1) | CH638464A5 (en) |
| DD (1) | DD141013A5 (en) |
| DE (1) | DE2800760C2 (en) |
| ES (1) | ES475099A1 (en) |
| FR (1) | FR2414022A1 (en) |
| GB (1) | GB2011874B (en) |
| IL (1) | IL56390A (en) |
| IT (1) | IT1160954B (en) |
| PL (1) | PL114221B1 (en) |
| PT (1) | PT68751A (en) |
| SE (1) | SE439152B (en) |
| SU (1) | SU957757A3 (en) |
| ZA (1) | ZA786759B (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5833164B2 (en) * | 1980-07-04 | 1983-07-18 | 花王株式会社 | Hollow granular percarbonate and its manufacturing method |
| JPS58182855U (en) * | 1982-05-31 | 1983-12-06 | マツダ株式会社 | car roof molding |
| JPS58186557U (en) * | 1982-06-04 | 1983-12-12 | 古河電池株式会社 | Storage battery case |
| JPS596285U (en) * | 1982-07-05 | 1984-01-14 | ホーチキ株式会社 | Fire alarm equipment receiver |
| DE59301882D1 (en) † | 1992-10-16 | 1996-04-18 | Solvay Interox Gmbh | Sodium percarbonates stabilized by coating |
| DE4306399C2 (en) * | 1993-03-02 | 1995-06-14 | Degussa | Process for the preparation of stabilized sodium percarbonate |
| DE4311944A1 (en) * | 1993-04-10 | 1994-10-13 | Degussa | Coated sodium percarbonate particles, process for their preparation and detergent, cleaning and bleaching compositions containing them |
| US5560896A (en) * | 1993-08-31 | 1996-10-01 | Degussa Aktiengesellschaft | Method for producing granulated sodium percarbonate |
| IT1276685B1 (en) * | 1995-06-08 | 1997-11-03 | Ausimont Spa | PROCESS FOR THE PRODUCTION OF SODIUM PERCARBONATE IN GRANULAR FORM |
| DE19717729A1 (en) * | 1997-04-26 | 1998-10-29 | Degussa | Coated sodium percarbonate particles, process for their preparation and their use |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2328803C3 (en) * | 1973-06-06 | 1982-11-25 | Peroxid-Chemie GmbH, 8023 Höllriegelskreuth | Process for the production of an abrasion-resistant, coarse-grained sodium percarbonate |
| DE2644148C3 (en) * | 1976-09-30 | 1983-05-11 | Degussa Ag, 6000 Frankfurt | Continuous process for the production of a compact, coarse-grained sodium percarbonate |
| DE2644147C3 (en) * | 1976-09-30 | 1983-05-19 | Degussa Ag, 6000 Frankfurt | Process for the production of a compact, coarse-grained sodium percarbonate |
| AT356627B (en) * | 1976-10-22 | 1980-05-12 | Treibacher Chemische Werke Ag | METHOD FOR PRODUCING SODIUM PERCARBONATE |
-
1978
- 1978-01-09 DE DE2800760A patent/DE2800760C2/en not_active Expired
- 1978-10-31 CA CA315,322A patent/CA1106136A/en not_active Expired
- 1978-11-01 SU SU782680502A patent/SU957757A3/en active
- 1978-11-06 PT PT68751A patent/PT68751A/en unknown
- 1978-11-15 ES ES475099A patent/ES475099A1/en not_active Expired
- 1978-11-16 DD DD78209130A patent/DD141013A5/en not_active IP Right Cessation
- 1978-11-24 IT IT69696/78A patent/IT1160954B/en active
- 1978-12-01 ZA ZA00786759A patent/ZA786759B/en unknown
- 1978-12-28 JP JP16133078A patent/JPS54101798A/en active Granted
- 1978-12-28 FR FR7836779A patent/FR2414022A1/en active Granted
-
1979
- 1979-01-08 PL PL1979212677A patent/PL114221B1/en unknown
- 1979-01-08 IL IL56390A patent/IL56390A/en not_active IP Right Cessation
- 1979-01-08 SE SE7900158A patent/SE439152B/en not_active IP Right Cessation
- 1979-01-08 BE BE6/46728A patent/BE873347A/en not_active IP Right Cessation
- 1979-01-08 GB GB79653A patent/GB2011874B/en not_active Expired
- 1979-01-09 CH CH17679A patent/CH638464A5/en not_active IP Right Cessation
- 1979-01-09 AT AT0016279A patent/AT386590B/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| DE2800760A1 (en) | 1979-07-19 |
| IL56390A0 (en) | 1979-03-12 |
| SE439152B (en) | 1985-06-03 |
| DD141013A5 (en) | 1980-04-09 |
| IT7869696A0 (en) | 1978-11-24 |
| AT386590B (en) | 1988-09-12 |
| FR2414022A1 (en) | 1979-08-03 |
| GB2011874B (en) | 1982-05-26 |
| SU957757A3 (en) | 1982-09-07 |
| DE2800760C2 (en) | 1983-01-27 |
| PL114221B1 (en) | 1981-01-31 |
| ZA786759B (en) | 1979-11-28 |
| ATA16279A (en) | 1988-02-15 |
| ES475099A1 (en) | 1979-04-16 |
| GB2011874A (en) | 1979-07-18 |
| IL56390A (en) | 1981-09-13 |
| IT1160954B (en) | 1987-03-11 |
| FR2414022B1 (en) | 1982-11-19 |
| PL212677A1 (en) | 1979-11-05 |
| JPS6327292B2 (en) | 1988-06-02 |
| PT68751A (en) | 1978-12-01 |
| SE7900158L (en) | 1979-07-10 |
| CH638464A5 (en) | 1983-09-30 |
| JPS54101798A (en) | 1979-08-10 |
| BE873347A (en) | 1979-07-09 |
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| MKEX | Expiry |