JPS59199800A - Manufacture of chromium-aluminum tanning agent - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a chromium-aluminum-based massaging agent from an alumina hydrate containing chromate.

Currently, as is well known, various rubbing agents have been proposed and used, but chromium agents and tannin rubbing agents are mainly used.

Chromium-based agents have been used for a long time because of their extremely excellent running effects, and various basic chromium sulfates are known based on various basicities and differences in chromium content.

However, even with such effective chromium agents, some drawbacks have been pointed out in line with the demands of the times. Chromium has become a major problem, and treatments and countermeasures are required, and various studies are being conducted.

Measures against this problem include (1) a so-called recycling method in which chromium-containing wastewater is returned to the chromium rubbing process for use;

(2) A method using a so-called highly adsorbent chromium massaging agent, which uses a massaging agent that improves the adsorption of chromium.

(3) A method of using chromium in the minimum necessary amount and in combination with other abrasives has been proposed and partially implemented.

Another drawback is that, because it is a chromium compound, coloring of the rubbed leather due to trivalent chromium remains, making it difficult to dye the leather.

In view of these problems, aluminum scouring agents, zirconium oxides, etc. that do not use any chromium compounds have been proposed, but they have not been replaced because of their inferior rubbing effect. Therefore, currently in the method (3) above, chromium-
Aluminum-based mulch is used. Seven of them were developed at Borland, and are said to be reaction products of sodium dichromate, aluminum sulfate, sodium bisulfite, and formic acid (salt), but the reaction system is extremely complex. There are many problems such as poor quality stability, and part of the sodium bisulfite decomposing during the reaction, resulting in insufficient reduction of hexavalent chromium and difficulty in adjusting basicity. On the other hand, a method for producing a ternary road additive of zirconium-aluminum PM has been proposed. (Special Public Sho Dacoda No. 7/No. 7) 0 Among these, an aluminum-chromium mixture is described as a precursor, but aluminum is more abundant than Nichiuchi Mu,
In its production, not only is hydroxide likely to be produced, but the rubbing effect itself cannot be expected.

In view of the above facts, the present invention has discovered the most industrially advantageous method in terms of both raw materials and production, and has developed a method that is excellent in terms of quality. The invention was completed.

That is, the gist of the present invention is to add acid to and dissolve alumina hydrate containing chromate, then add a reducing agent to reduce hexavalent chromium, and then neutralize with an alkali agent. The present invention relates to a method for producing a chromium-aluminum-based rubbing agent characterized by making it highly basic.

In the present invention, the alumina hydrate containing chromate, which is the starting material, is most rational and advantageous to effectively utilize by-products in the chromate production process, and in particular, sodium chromate from chromium ore. In the manufacturing process, it is preferable that a large amount of alumina hydrate is produced as a by-product depending on the manufacturing process. In other words, although this alumina hydrate generally has a high water content and contains a large amount of hexavalent chromium due to its nature, it is difficult to completely separate this alumina, and there are many problems in its disposal. In other words, sodium chromate is produced by oxidizing and roasting a mixture of chromium ore, a soda source, and a filler such as lime, and leaching it with water. Production methods such as sintering or direct melting of chromium ore and alkali in an oxidizing atmosphere are gradually being adopted, and since a large amount of chromium ore is dissolved, the alkali chromate leachate is neutralized and the alumina content is converted into alumina hydrate. A process of insolubilization and separation is required. Therefore, the alumina hydrate produced as a by-product in this step is a precipitate containing alkali chromate, and the "rt OaA4's ratio can be adjusted appropriately by washing or adding alkali chromate, which is most suitable for the method of the present invention. It becomes a raw material.

The alumina hydrate containing tetramate, which is a starting material, has a composition in a weight ratio of O≦Cr, o3/At, O.

It is desirable that the alumina hydrate is in the range of ≦3, and therefore the above alumina hydrate is used for industrially advantageous production.
In that case, the by-product from the chromate production process described above can be used as is. It goes without saying that the composition can be adjusted within the above range if necessary.

In view of the above reasons, it goes without saying that other means of preparing the starting material can be used, namely a mixture of chromate or dichromate and alumina hydrate.

In the present invention, the chromate contained in the alumina hydrate means one containing seven or more of alkali monochromates, alkali dichromates, and chromium trioxide.

Next, an acid is added to the alumina hydrate containing the chromate to dissolve it. As the acid, sulfuric acid and hydrochloric acid are preferably used. The reaction at this time can be expressed by the following equations (11 and (21), where the alumina hydrate containing chromate is simply a mixture of sodium romate and aluminum hydroxide, and the acid is sulfuric acid.

, 2 Na, Cr O, 10H, So, → Na, Cr,
○, bow H, O+Na, So, fl)2 Al(OH
)3+,,? H, So, →At, (So, )s
-t-4H20 (21 In this case, the amount of sulfuric acid added is (1)
, O represented by formula (2) Next, after addition of acid, hexavalent chromium (Na
, Cr,Ol-,2a,o). The reducing agent used at this time may be sulfur dioxide gas, an inorganic reducing agent such as sodium bisulfite, or an organic reducing agent such as glucose, honey, alradhi or hydrogen. , 07 bow Hz O'+,? 80. → Cr(OH)304+Na2 so, 10H, O(3) For glucose: #Na, Cr, 0PJH, ○+/koH, So, + C,
Hl, O, -+ffcr(OH)So, -f4Na
2so, +ACO, +Coni rH,o (indicated by 41, the product at this time is basic chromium sulfate, which corresponds to a chromium scouring agent with a basicity of 33.3%.

Next, aluminum sulfate [At, (
so, )s) do not have bast properties and must be made highly basic by adding an alkaline agent to give them bast properties.

The alkaline agent at this time is not particularly limited as long as it neutralizes and makes it highly basic, but caustic alkali, alkali carbonate, alkali bicarbonate, aluminum/acid soda, etc. can be used. Among these, alkali bicarbonate is particularly good because it is preferable for operation to use an alkaline agent that is as mild as possible.

For example, the reaction to make basicity 33.3% using sodium bicarbonate is kt, (So, )s +2NaHco, →yAz(
oH)so, -1-NalSO4-h2co.

In addition, in order to prevent the formation of aluminum hydroxide and maintain the specified basicity during high base operation, it is desirable to add a carboxylic acid compound.As is well known, the carboxylic acid compound is used to mask OH groups during high base operation. For example, acidic acid, oxalic acid, corkic acid, glutaric acid, adipic acid, phthalic acid, tartaric acid, citric acid or lactic acid are used as agents, and they are also used as alkali metal salts, alkaline earth metal salts Alternatively, it may be an ammonium salt, and at least one or two or more thereof may be selected as appropriate.

The alkaline agent is added to the base at room temperature to OC to neutralize it and make it highly basic.

Next, after the addition of the alkali agent is completed, the mixture is aged for a while, if necessary, and then spray-dried by a conventional method to form a granular product. The particle size of the product is preferably such that it can dissolve in cold water and pass through a mesh, but is not limited thereto.

The composition of the chromium-aluminum based aggressive agent obtained by the present invention is often the proportion (wt%) of Cr, 03: +
2~CoS% Preferably 7~-0%Carboxylic acid compounds are used as masking agents for OH groups when forming a high base, for example, formic acid, acetic acid, oxalic acid, corkic acid, and glutaric acid. , adipic acid, phthalic acid, tartaric acid, citric acid, or lactic acid, etc., and they may also be alkali metal salts, alkaline earth metal salts, or ammonium salts, and at least seven or more types are selected as appropriate. do.

The alkaline agent is gradually added to neutralize it under temperature conditions of room temperature to 1roC to make it highly basic.

After the addition of the alkaline agent, the mixture is continued to ripen for a while, and if necessary, after one sieve, it is spray-dried in a conventional manner to form a product into granules. The particle size of the product is preferably such that it can dissolve in cold water and pass through a qo mesh, but is not limited thereto.

The composition of the chromium-aluminum-based glazing agent obtained by the present invention is often determined by the following ratios (wt%): Cr, O,
Co~2S% Preferably 7~20%A7! ,,O,
: Co~J, t% Preferably S~76% Basicity Knee 0-jjt% Preferably λg-! 10%? (
The chromium-aluminum grouting agent of the present invention improves the heat resistance of tanned leather using an aluminum grout alone with chromium, and also reduces the amount of lumber in wastewater to at least the level of bamboo in the conventional method, reducing the amount of chromium contamination. It has the effect of significantly reducing the amount of chromium used, and the following advantages can be listed: - The amount of chromium used can be reduced, and the amount of chromium in waste water can be reduced.

■ The heat resistance of the RPM road agent and the aluminum g agent is almost the same as that of chrome tanned leather, and the color tone of the tanned leather is whiter than that of chrome tanned leather, and it has a good dyeability. becomes good.

■ The final result is a tanned leather that is flexible, has good grain fineness, and has excellent dyeability. Regarding the usage of the chromium-aluminum system obtained by the present invention, we will explain how to use it with a normal chrome rubbing agent. There is basically no difference, and the tanning process is not complicated at all.

Thus, according to the present invention, hydrated alumina containing chromate, which is a by-product from the chromate manufacturing process and which is difficult to dispose of, can be effectively recycled as a valuable product.

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

Example 1 A leaching solution of sodium chromate (Na, Cry.

-7% to dissolved sodium aluminate (AZ, O
.

) was neutralized by adding sulfuric acid to form a precipitate of alumina hydrate, which was subjected to overseparation to obtain an alumina hydrate containing sodium chromate having the following composition.

Composition: H, ONa, Cry, At(OH).

% 40.0 /
ta, t-〇, /this hydrate/, 00
Water against 01y! ;00kl, sulfuric acid (H,80,?f
%) was placed in a glass-lined reaction vessel equipped with a thermometer and a stirrer, heated to 90C, and stirred and mixed for 60 minutes.

After confirming that the alumina hydrate was completely dissolved, sulfur dioxide gas was injected to reduce all the hexavalent chromium to trivalent chromium.

After confirming that the hexavalent chromium content is completely eliminated by diphenylcarbazide coloring test,
It was gradually added over 20 minutes to make it highly basic.

After addition, the mixture was filtered according to a conventional method and then spray-dried to obtain a granular product 1107.

Product composition is H, O/6. in weight%, basicity 33.3%, Cr, O, /A40. The weight ratio was 01, and the water solubility was very good.
12) Example: Sodium monochromate solution (Na, Cry, ?2゜0) was added to the same alumina aquarium as in Example 1.
tf6) A7! ; kf, sulfuric acid (H, So, q g section)
,! t/Aki was placed in a glass-lined reaction vessel equipped with a thermometer and a stirrer, heated to 90C, and stirred and mixed for 60 minutes.

After confirming that the alumina hydrate was completely dissolved, sulfur dioxide gas, 24 (9 kp) was injected to change all the hexavalent chromium to trivalent chromium. After confirming with the cytochromic test, bicarbonate of soda al'ykg was gradually added over 720 minutes to make it highly basic.
Spray drying gave a granular product/A+kp.

Product composition is Cr(OH)30. 2 A, /wt% (Cr,
O, conversion is, 0%) At(OH)So, 22.
0% by weight (A, t2o, converted g, Na25o,
33. lI weight ratio H20ig, z weight ratio basicity, 7.7. ．． 7%, Cr2O3/A40. Weight ratio 1. The water solubility was very good.

Example 3 For the same alumina water consumables /,000 kg as in Example 1,
Water 2A; Oky, sulfuric acid (H2SO, ? 1%) 43/k
The mixture was placed in a glass-lined reaction vessel equipped with a thermometer and a stirrer, heated to θC, and stirred and mixed for 10 minutes.

After confirming that the alumina hydrate was completely dissolved, glucose (C6H12O6 left 0q6) was added to denature all hexavalent chromium to trivalent chromium. The amount of glucose required at this time was A kf was gradually added over a period of 1 gO to increase the salinity. After the addition, 1 filtration was carried out according to a conventional method, and then spray-dried to obtain a granular product of 19 kg. So, ) 0.7 & /j. Weight% (Cr203 equivalent?, g%) At(OI()
/, left (So, ) 0. the law of nature! Core, 1% by weight (A4
0. Conversion/i/)HCOOHa
left. 3wt% Na25o, 311
．． 0 wt% H, O/g, 0 wt%, basicity ro, o%, Cr2O,/At, 03 weight ratio O07, HCOONa is Cr, O, 40.
The water solubility was very good, with O6S mol.

Test Example 1 A commercially available basic chromium sulfate tanning agent (Cr, O) was added to 100 parts by weight of pickled leather (light steer).

The product was manufactured using a drum at 20 rpm in a conventional manner using 70 parts by weight of 3.3% and 33.3% basicity.

As a result, the Cr, 03 content, and heat shrinkage temperature of the obtained tanned leather, and the Cr, 03 content of the tanning wastewater were 6. The measurements of C+, OB content, and heat shrinkage temperature were conducted using JIF3K.
A! ,';0 It was carried out in accordance with the leather test method.

Test Example: Using 3 parts by weight and 70 parts by weight of the chromium-aluminum tanning agent manufactured in Example 1 for the same io weight part of pickled leather as in Test Example 1, went.

The Cr2O3 content, heat shrinkage temperature, and tanning wastewater of the resulting tanned leather were as follows.

Comparing with test example 1 (1) The heat shrinkage temperature is about the same.

(2) The content of Cr and O in the tanning wastewater has been reduced to 1/2.

These features are obvious.

Claims (1)

[Scope of Claims] l A chromium-based product characterized by adding an acid to an alumina hydrate containing a chromate to dissolve it, then reducing hexavalent chromium, and adding an alkali agent to make it highly basic. Manufacturing method of aluminum-based massaging agent. The manufacturing method according to claim 2, wherein the alumina hydrate is an alumina hydrate by-produced from a chromate manufacturing process.