JPS59116127A - Manufacture of stabilized basic iron salt solution - Google Patents

Abstract

PURPOSE:To obtain a stabilized basic iron salt soln. by manufacturing a basic iron salt contg. Cl<->, NO3<-> or SO4<-> in the presence of a phosphorus compound. CONSTITUTION:The hydroxide, oxide and carbonate of Na, Ca, Ba, K or the like are added to a soln. prepd. by dissolving an iron compound in one or more kinds of acids such as hydrochloric acid, sulfuric acid and nitric acid, and they are reacted in the presence of a phosphorus compound to introduce an OH group into the iron salt, thereby producing a basic iron salt. The preferred phosphorus compound is an inorg. phosphorus compound such as phosphoric acid, and the preferred molar ratio of P/Fe is about 0.04-0.25. A basic iron salt soln. causing no gelation and having superior properties as a flocculant for waste water is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing stabilized basic iron salts containing iron.

Conventionally, aluminum-based flocculants such as polyaluminum chloride, poly4Jk, and acid aluminum have been widely used for purifying various types of wastewater and polluted water.

In addition, as flocculants other than aluminum, ferric chloride,
Iron-based flocculants such as ferric sulfate or basic salts thereof are known, and these agents 1) block the aggregated material in a short period of time;

2) Similarly, the sedimentation of the generated block is large.

3) Strong ability to adsorb harmful elements.

4) Generates sludge with good dewatering properties.

5) Effective for organic wastewater.

Although they have superior properties compared to aluminum-based ones, they are strongly acidic and easily hydrolyzed. In particular, basic iron salts are even more easily hydrolyzed and are unstable, such as causing gelation during the manufacturing process or during storage. Difficult to handle in wet condition.

The present inventors have repeatedly investigated the stabilization of iron-based basic salts, which have excellent properties as flocculants, as described above. As a result, basic iron salts produced in the presence of phosphorus compounds have been It is extremely stable, with no gelation or other deterioration, not only during the process but also during storage as a product, and even when used as a flocculant for purifying wastewater, it is superior to conventional flocculants. It was discovered that it has certain properties.

The present invention requires that the basic iron salt be produced in the presence of a phosphorus compound. The present inventors have confirmed that even if a phosphorus compound is added to a basic iron salt obtained by a conventional method, the effects seen in the present invention cannot be obtained.

The phosphorus compound used in the present invention may be either organic or inorganic, but inorganic phosphorus compounds are preferred.

Specific examples of inorganic phosphorus compounds include phosphoric acid, phosphoric acid-
These include sodium, phosphates such as disodium phosphate, polyphosphoric acid, and metaphosphoric acid.

In the present invention, the phosphorus compound may be added to the reaction system at any time as long as it is not after the desired basic iron salt has been produced.

For example, a phosphorus compound may be allowed to coexist when an iron-based compound is decomposed with hydrochloric acid, sulfuric acid, etc., or when an alkali is added to the decomposed product obtained by the decomposition to form a basic iron salt.

The amount of phosphorus compound to be removed varies depending on the type of phosphorus compound used, the type of basic iron salt intended, the basicity, and the iron concentration, but in general, as the basicity increases, the iron concentration also increases. It is preferable to increase the amount of the phosphorus compound added (to increase the P/Fe molar ratio). In the present invention, the P/Fe mo AJ ratio is 0.04
A range of -0.25 is preferred.

The iron-based compound used in the present invention is not particularly limited as long as it contains one or more of CI-+NO3-+5O4-2 when finally made into a basic iron salt. Especially 804
-2 makes the sound effect of the present invention even more noticeable.

Also, it is acceptable to include aluminum or titanium in addition to iron.

In general, when aluminum coexists in a basic iron salt, how to obtain a stable salt is A! It is said that the molar ratio of , /Fe must be 1 or more (Special Publication Showa 4) -170
However, according to the present invention, an extremely stable basic salt can be obtained even when the At/Fe molar ratio is less than 1.

Although the mechanism of action of the phosphorus compound used in the present invention in the basic iron salt production system is not necessarily clear, the phosphorus compound coexisting in the iron salt solution binds to iron atoms, and the OH added to provide basicity It is inferred that gelation of the basic salt is inhibited because the iron atom acts as a crosslinker with the group, but at the same time partially destroys the ice-like structure of the water present.

In the present invention, hydroxides, oxides, and carbonates of sodium, calcium, barium, potassium, etc. are added to a solution of Fe-based compounds in one or more acids such as hydrochloric acid, sulfuric acid, and nitric acid in the presence of a phosphorus compound. An OH fund is introduced into the iron salt through an addition reaction to form a basic iron salt.

In the present invention, the basicity of the salt can be varied at will depending on the purpose and is not particularly limited.

The main effects of the present invention described in detail above are listed below.

(1) Basic iron salts that are stable and have a high basicity can be produced by the method of the present invention, although they could not be produced by gelation in the past.

(2) When the basic iron salt obtained according to the present invention is used as a flocculant, it has many effects.

b) Since Fe'ie is the main component, the production cost is lower than that of A type flocculants.

1) The rate of floc formation is faster than that of KT flocculants.

c) The sedimentation speed of flocs is faster than that of A-type flocculants.

2) The use of alkaline auxiliaries becomes unnecessary or is significantly reduced.

e) Excellent cake releasability.

f) Corrosivity is reduced.

g) The range of appropriate injection amount is wide compared to PAC etc.

Next, examples of the present invention and examples of aggregation tests using products of the present invention will be shown.

Next, the present invention will be explained in detail with reference to Examples.

Examples 1 to 4 and Comparative Examples 1 to 13 While stirring a ferric chloride solution at room temperature, various compounds were added so that the molar ratio to Fe was 0.10, and the iron concentration was 10. Ow/w% (CaCO3/
An aqueous calcium carbonate solution is added over about 1 hour so that the molar ratio of FeC15) is 0.75.

The storage stability of the solution was observed by leaving it at room temperature.

The results are shown in Table-1.

Example 5 While stirring a ferric chloride solution at room temperature, the molar ratio of phosphoric acid to Fe was 0.04, 0.07°0.
．． 10 and 0.20. This mixed solution has a molar ratio of (CaCO5/Pa) of (1,45,0
, 6-5.

n, 85, 1. (Add calcium carbonate so that the concentration is 15. Adjust the iron concentration to 5, 8, with distilled water.) Ow/w
The storage stability of the solution was observed. The results are shown in Table-2. Similarly, in the case of iron sulfate, Fe
The molar ratio of phosphoric acid to 0.025 and 0.10.

(CaCO5/li'
molar ratio of e) is 0.75, 0.90, 1.00
, add calcium carbonate to make it 1.20. Separate the generated gypsum and reduce the iron concentration to 10. Ow/w
% and observed the storage stability of the solution. The results are shown in Table-37.

Table-2 A mark of 0 indicates stability for three months.

Table-3 A 0 mark indicates stability for three months.

Example 6 Ferric chloride aqueous solution (FeCl3.37-46 w/w%
) to 100 parts by weight of phosphoric acid water bath solution (H3PO4, 85w/
w%)'e0.27 part by weight was added and stirred at 30°C for about 30 minutes. A total of 19.7 parts by weight of calcium carbonate was added to this mixed solution and reacted for about 1 hour with stirring. Adjust the iron concentration to 10.0 with distilled water. Adjust to ow/w and pour out the dark brown basic iron chloride bath solution. The composition of this solution is Fe2O2] 4-30
w/w %, total CI-12-7 (1 w/w %.

Ca08.56 w/v%, P2OlIn, 13
w/w'ly, (CaO/Fe) molar ratio (
The molar ratio of 1,85, (P,/Fe 2 ) is 0°01.

For comparison, an iron concentration of 11'1. A basic iron chloride bath solution of Ov/w is obtained. All of these were stored at room temperature and changes in their conditions were observed. Changes during storage Example 7 Ferric sulfate aqueous solution (Fe2(SO4)3, 43.45
w/w%) to 100 parts by weight of phosphoric acid aqueous solution (HsPO4,
85 w/w%) was added, and about 3 parts by weight was added at 30°C.
Stir for 0 minutes. 26.1 parts by weight of calcium carbonate is added to this mixed solution and reacted for about 1 hour with stirring.

The produced calcium sulfate 'kF was separated and distilled water was added to the filtrate to bring the iron concentration to 10. Adjust to Ow/w%. The composition of the obtained blackish brown basic iron sulfate bath solution was Fe2O.

14.30 w/w%, SO45,16w/w%
, Ca00.03w/w% P2O110,30w
/w%. Comparison (7M, = obtain a basic iron sulfate bath solution with an iron concentration of 10.0w/w by changing the amount of melicic acid added and using the same method as above. Store these at room temperature and observe the change in the state. The presence or absence of changes during storage is shown in the table below.

Example 8 Ferric nitrate aqueous solution (1;”e (No,), l 35
．． 86 w/w%) to 100 parts by weight of phosphoric acid aqueous solution (H3
0.68 parts by weight of PO4, 85 w/w%) was added, and 30
Stir at 'C for about 30 minutes. 12.6 parts by weight of calcium carbonate is added to this mixed solution and reacted for about 1 hour with stirring.

Iron concentration f in distilled water 7. Adjust the Ow/w% to obtain a dark brown basic iron sulfate bath liquid gold. The composition of this solution is Fe2O3
10,Ow/%+Ca06. Ow/w%, Pt0a
It was 0-35 w/w%. For comparison, the iron concentration was set to 7.5% using the same method as above, but changing the amount of phosphoric acid added. Ow/w%
A basic iron nitrate solution is obtained. These were stored at room temperature and changes in their condition were observed. The presence or absence of changes during storage is shown in the table below.

Example 9 Ferrous chloride aqueous solution (FeC/-2, 30,82 W/W%
) 100 parts by weight t Disodium phosphoric acid dihydrate (Na
, HPO, -2) (20) k 0.9 part by weight was added, 3
Stir at 0°C for about 30 minutes. To this mixed solution, 8 parts by weight of sodium nitrite (NaN0t)'cO was added as a catalyst and oxidized with oxygen for about 2 hours in an oxygen atmosphere. After the reaction is complete, perform aeration and adjust the iron concentration to 11.0 seconds with distilled water.
Adjust to lwchi. The composition of this solution is Fe20sl 5
゜50 W/W Z, Feo O,2], w/w
% +Total C/-13,93w/vr%, P20!
+ 0.29 w/w % terror. ratio e no f:
A basic iron chloride solution with an iron concentration of 11.0 w/w% is obtained by the same method as above except that 1k of phosphoric acid is added.

These were stored at room temperature and changes in their condition were observed.

The presence or absence of changes during storage is shown in the table below.

Example 10 Ferric chloride water bath liquid (FeC15, 38,46 w/w%)
40.0 parts by weight and ferric sulfate aqueous solution (Few(so,)
, .

37.52 W/W%) 139.0 parts by weight were mixed and stirred, and a phosphoric acid water bath solution (H3PO4, 85 w/w%) was added to this.
Add 1.64 parts by weight of and stir at 30°C for about 30 minutes.

33.8 parts by weight of calcium carbonate is added to this mixed solution and reacted for about 1 hour with stirring. The generated calcium sulfate was separated from each household, and distilled water was added to the filtrate to determine the iron concentration k10. O
Adjust to w/w%. The composition of this solution is Fe2O,14
-30slw%, +so, 2.58 w/w%, total Ct5.08 w/w%, CaOO, 03w/w
%, P2O, C1, 51slw%. For comparison, an iron concentration of 10. A basic iron salt solution of Ow/w% is obtained. This was stored at room temperature and changes in its state were observed. The presence or absence of changes during storage is shown in the table below.

Example] 1 Ferric chloride aqueous solution (FeC1, g, 38.46 w
/w%) 87.3 parts by weight and aluminum chloride (A)
ct, , 61 (20) were mixed and stirred, and an aqueous solution of phosphoric acid (HPPO4, 85 w/w %
) k 0.95 part by weight was added and stirred at 30°C for about 30 minutes. 17.6 parts by weight of calcium carbonate is added to this mixed solution and reacted for about 1 hour with stirring. Adjust the iron concentration to 9.0 with distilled water. Adjust the Ow/w% to obtain a dark brown basic salt solution. The composition of this bath liquid is Fe2O212-87w/w
% r At2032.09 w/w Chi, total CL 21
．． 47 w/w%, P20! I O, 46 w/w%.

cao was 7.68 w/w%. For comparison, a basic salt bath solution with an iron concentration of 9° Ow/w was obtained in the same manner as above except that the amount of phosphoric acid added was changed. These were stored at room temperature and changes in their condition were observed. The presence or absence of changes during storage is shown in the table below.

Example 12 Ferric chloride aqueous solution (FeC15, 38,46 w/wqb
) 87.3 parts by weight, titanium sulfate aqueous solution (Tl(504)
2.

30 w/w%) 20.8 parts by weight and 12.7"f1f parts of aluminum chloride (Atct, 6H20) were mixed and stirred, and to this mixture was added an aqueous solution of phosphoric acid (HsPO+,
Add 0.95 parts by weight of 85 w/w
Stir for about 30 minutes.

17.6 parts by weight of calcium carbonate is added to this mixed solution and reacted for about 1 hour with stirring. Separate the produced calcium sulfate 'kF' and add distilled water to the filtrate to determine the iron concentration k8. O
Adjust to w/w%. The composition of this solution is F6zOa]
l, 44 y/w% * At20s 1-86
w/w%.

Tl0t 1.44 w/w%, total Ct-:t9
．． 10 w/w%, P20aO, 40w/w%
, CaO4, 81w/w%, So, 0.05w
/w%. For comparison, a basic salt bath solution having an iron concentration of s, ow/w% was obtained in the same manner as above except that the amount of phosphoric acid added was changed. These were stored at room temperature and changes in their condition were observed. The presence or absence of changes during storage is shown in the table below.

Reference Example Next, in order to find out the flocculation effect of the iron basic chloride solution obtained in Example 5, a jar test and a sedimentation test were conducted while comparing it with various inorganic salt flocculants. The results are shown in the table below.

(a) Jar test The treatment conditions were stirring at 150 rpm for 3 minutes and stirring at 30 rpm for 12 minutes, and after 10 minutes, the supernatant fL was taken and its turbidity 'ft was measured.

Raw water Hexagonal suspension water Turbidity 50° Water temperature 18℃pH
7,3 (b) Sedimentation test The processing conditions were as follows: A sample was placed in a 500rnt female cylinder and the sample was stirred upside down twice, and the sedimentation rate at the interface was measured.

Claims (1)

[Claims] In the presence of phosphorus compounds, C1-, No; , 5o4-
A method for producing a stabilized basic iron salt bath solution patented for producing a basic iron salt containing one or more of the following: