FI80869C - UTFAELLNINGS- COH LIMNINGSAEMNE SAMT FOERFARANDE FOER DESS FRAMSTAELLNING. - Google Patents

Description

1 80869

The present invention relates to low-base aluminum hydroxide chloride (hereinafter abbreviated as VEAHK) and to a process for its preparation. The general formula for aluminum hydroxide is | A1 (0H) Cl Ί, where 0 <x <3 and y = 3-x and n> l. l χ yj n

It is prepared by reacting hydrochloric acid with alumina or aluminum hydroxide (collectively, aluminum hydrate).

It is known that aluminum hydrate reacts with a salt acid to form aluminum chloride, especially when more hydrochloric acid is used than would be stoichiometrically necessary. The matter has been dealt with e.g. in several patent applications, such as in SE-A-407399, 15 according to which the product is manufactured at a high temperature (160-270 ° C), which results in high production costs. In addition, the product differs in basicity from the VEAHK object of the invention. The product according to the second SE patent 388191 differs from the VEAHK which is the subject of the invention due to its base-20 reason. In addition, according to SE-388191, it is necessary to use 2 to 5 times more stoichiometrically more aluminum hydrate than in the preparation of the VEAHK which is the subject of the invention.

FI patent application 854463 discloses a process for the preparation of a polyaluminum chloride of the presumed formula Ala (OH) ^ (SO4) Ccl3a-b-2c3oka which is suitable for use as a flocculant in water purification technology and to replace aluminum sulphate in paper resin sizing. In this known process, the temperature is low 30 (<100 ° C), whereby the reaction time is long (up to 15 h). GB-A-2128977 A describes a process for the preparation of basic aluminum chloride sulphate for water treatment which is completely different from the VEAHK of the invention, since the former is prepared by reacting basic aluminum chloride and basic aluminum sulphate. In addition, the the publication states that the aluminum chloride used is prepared by reacting hydrochloric acid and alumina with each other. This product is then reacted with aluminum hydroxide.

It is known from FR patent 2584699 to prepare aluminum chloride sulphate useful as a flocculant by allowing calcium chloride, calcium carbonate and aluminum sulphate to react with each other to obtain gypsum waste.

The object of the invention was to provide a product for use in the purification of humus-containing surface waters, e.g. for drinking water purposes, which product would also be useful in pulp sizing of paper as a resin sizing retention agent without the disadvantages of known products.

Surprisingly, it has been found that by reacting aluminum hydrate under special conditions with hydrochloric acid so that there is a stoichiometrically little more aluminum hydrate than hydrochloric acid compared to what would be needed to obtain aluminum chloride (AlCl 3) alone, the reaction product was

According to the invention, VEAHK is prepared by reacting aluminum hydrate with hydrochloric acid at elevated temperature and pressure, the aluminum hydrate having an Al content of 29 to 31% and a stoichiometric amount of 1.01 to 1.15 times the amount of 100% hydrochloric acid. The acid is added as about 30-37% aqueous solution. The starting materials are allowed to react with each other at a temperature of 110 to 150 ° C and a pressure of 2 to 4 bar for about 2 to 5 hours.

30 Some of the excessly dosed aluminum hydrate remains unreacted. This can be used as part of the raw material needed for the new batch, as the reactivity of the residue is almost in the same range as that of the unused aluminum-35 hydrate, depending on the purity of the original aluminum hydrate. Surprisingly, it has been found that if the unreacted aluminum hydrate left over from the previous batch is removed from the reactor before the new batch is introduced, less aluminum hydrate is consumed in the reaction than if the above unreacted residue had been left in the reactor.

The composition of VEAHK prepared as described above is Al (OH) Cl. , where 0.4 <a <0.8, and b = 3-a and 5 n> l. The aluminum content of the product is 7.0 to 7.5% by weight. The VEAHK of the invention differs from other aluminum hydroxides, some of which are also referred to as polyaluminum chlorides (PAC), in that the compound of the invention contains significantly less hydroxide than other similar products having the molecular formula [α! Cl ^ j ^, where typically 1.0, <x £ 2.5.

Surprisingly, it has been found that VEAHK is excellently suitable for the treatment of humus-containing surface waters, for example for drinking water purposes.

15 Surprisingly, it has also been found that the use of VEAHK in paper pulp sizing as a retention agent for resin sizing has achieved good results in different sizing pH ranges.

The following examples illustrate the invention.

Example 1 An empty reactor was charged with 31.6% by weight hydrochloric acid solution in an amount of 30.35 kg of 100% HCl. 0.654 kg of water was added to the reactor. The mixture was switched on. 9.454 kg of aluminum hydrate with an Al content of 32.5% and a moisture content of 2% were added. The heating was switched on and when the reaction had begun, the temperature rose to 130 ° C due to the exothermic reaction and the pressure to 2.4 bar (abs.), Under which conditions the reaction was allowed to proceed for 2 h 45 min. It was then cooled to 80 ° C and the clear solution was removed. The resulting kir-30 kas solution is the desired end product, which was obtained with a solution content of 36.32 kg at 452.9 g / l and an Al content of 7.3%. The remaining 0.197 kg of precipitate was left in the reactor. At the start of the next batch, 31.6 wt% hydrochloric acid was then required only in an amount such that 26.21 kg of 100% HCl was present.

4 80869

Example 2

The reactor was charged with 24.35 kg of hydrochloric acid calculated as 100% HCl. A hydrate with an A content of 26.87% (humidity 10.3%) was charged with 33.7 kg. The heating was switched on. When the temperature was 79 ° C, the heating was turned off. In this case, due to the rapid heating, the pressure was 3.5 bar (abs.). The heat of reaction raised the temperature to 132 ° C at a pressure of 2.9 bar (abs.). The heating was switched on again, at which point the temperature rose to 135 ° C, but the pressure had dropped to 2 bar (abs.) When the mixture was cooled.

The amount of precipitate in the product was 6% and the Al content of the solution was 8.2%. The reaction time was 2.5 h.

Example 3 Several laboratory experiments were performed comparing the VEAHK of the invention to aluminum sulfate and three commercial basic aluminum hydroxides. The experiments were performed as precipitation experiments in the laboratory. Fresh Kokemäenjoki 20 surface water was used as the water to be treated. In each case, the precipitation pH was adjusted to 6.0 with lye solution. Reported values (KMnO 2 consumption and turbidity) were measured from centrifuged samples. KMnO 2 consumption in one way indicates the amount of organic matter in the water and thus also the amount of humus.

The compositions and aluminum-2 concentrations of the coagulants used were as follows:

Aluminum sulphate: A12 (SO4) 3 14H2O Al-pit. about 9.1% "Kempac" (manufactured by Kemira Oy): AliOH) ^ 2C ^ 1 7 ^ SO4 ^ 0 1 Al-pit. about 5.4% VEAHK: Al (OH) Cl9. Alps. n. 7.3% 30 '' 5 80869

Laboratory tests resulted in:

The KMnO 2 consumption of raw water is 53.0 mg / l and the turbidity is 3.0 NTU

Water to be purified from the coagulant 5 Coagulant Dose level caused Al-pit. KMnO 2 consumption Turbidity (mg / l) (mg / l) (mg / l) (NTU)

Aluminum sulphate 65 5.9 14.2 0.23 "Kempac" 65 3.5 23.9 0.75 10 "Kempac" 105 5.7 13.7 0.15 VEAHK 65 4.7 12.3 0, 15

Example 4

The procedure was as in Example 2 and an aluminum sulphate and VEAHK coagulant with the same composition and aluminum content was used, but the commercial coagulant was "Ekoflock": Al (OH) 2 gClg 3 ^ ® ° 4 ^ 0 1 Al-pit · n · 5.3% (manufactured by Ekoflock AB, Sweden) 20

The results obtained were as follows:

KMnO 4 consumption of raw water 50.6 mg / l, turbidity 1.9 NTU

2 5 Water to be purified from the coagulant

Coagulant Dose level caused by Al-pit. KMnO 2 consumption Turbidity (mg / l) (mg / l) (mg / l) (NTU)

Aluminum:. (Sulphate 65 5.9 14.5 0.07 30 '"Ekoflock" 65 3.4 17.7 0.15 I "Eco flock" 113 6.0 12.9 0.12 jvEAHK_65_4.7__12.9_0.06

Example 5 35 The procedure was as in Example 2, using a VEAHK coagulant of the same composition, but the commercial coagulant was "Sulzfloc": Al (OH) 1? Alps. about 9.6% (manufactured by Sulzer Brothers, Winterthur, Switzerland) 5 The results obtained were as follows:

Consumption of raw water KMnO 4 ~ 62.9 mg / l

Water to be purified from the coagulant

Coagulant Dose level caused by Al-pit. KMnO 2 consumption (mg / l) (mg / l) (mg / l) "Sulzfloc JG 19" 62.5 6.0 14.6 VEAHK 80.0 5.8 14.1 15

Example 6 The use of VEAHK in pulp sizing of paper as a resin sizing retention agent in different sizing pH ranges was performed on a laboratory sheet mold. Water absorbency was measured as Cobb ^ Q values. The pulp used consisted of 20 2/3 bleached pine sulphate pulp (25 ° SR) and 1/3 thermomechanical pulp (60 CSF). At some test points, 19% calcium carbonate was added to the pulp.

In the first four cases, aluminum sulfate and VEAHK were added in such amounts that the aluminum concentrations resulting from the products were equal. This resulted in the following: 7 80869 - d

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From Examples 2 and 3, it is found that VEAHK achieves a clearly better removal of humus than aluminum sulphate commonly used in water treatment, although the aluminum content of aluminum sulphate is about 25% higher than that of VEAHK. It can also be stated that VEAHK achieves a better result than the comparable commercial aluminum hydrochloride solutions with the same dosage of products. The result of commercial products does not improve until they are dosed to such an extent that the aluminum concentration due to the products is approximately the same as that due to aluminum sulfate. In the case of Example 4, the products were dosed so that the resulting aluminum concentration was the same in both cases of Example 4.

It can be seen from Example 5 that the VEAHK object of the invention can be used as a retention agent for mass sizing not only in the acidic region but also in the so-called in a pseudoneutral range, although the amounts of retention aid and adhesive increase. On the other hand, since VEAHK does not contain sulfate, gypsum problems (CaSO 4) in paper machine systems are avoided when using calcium carbonate-filled pulps.

Claims (11)

1. Minor basic aluminum hydroxychloride, characterized in that it has the formula [Al (OH) aClb] n, in which 0.4 <a <0.8, b = 3-a and n> 1. Process for the preparation of a minor basic product according to claim 1 by reacting aluminum oxide or hydroxide with hydrochloric acid, characterized in that the reaction is carried out at a temperature of 110-150 ° C and under a pressure of 2 - 4 bar (abs.), Wherein alumina or hydroxide is used in a stoichiometric low excess compared to the acid. 3. A process according to claim 2, characterized in that the reaction time is 2 to 5 hours. 15 4. A process according to claim 2, characterized in that the starting materials are heated evenly to the temperature at which the reaction begins. 5. A process according to claim 2, characterized in that one starting material is a 30-37% aqueous hydrochloric acid solution. Process according to any one of claims 2-5, characterized in that alumina or hydroxide is used 1.01 - 1.15 times the amount of 100% hydrochloric acid. 25 Process according to any of claims 2-5, characterized in that the second starting material is waste from alkaline aluminum pickling, such as or neutralized with a suitable acid. Process according to any one of claims 2-5, characterized in that the second starting material is waste from alkaline pickling of aluminum, such as or neutralized with a suitable acid, and aluminum hydroxide or oxide. Use of the product of claim 1 for purifying water, preferably humus-containing water. «80869 Use of the product according to claim 1 as an aid in the drying of sludge. Use of the product according to claim 1 in papermaking in pulp sizing as well as resin retention agent in acid as well as in pseudoneutral sizing.