CN1203195A

CN1203195A - Process for producing poly-iron chloride

Info

Publication number: CN1203195A
Application number: CN 98103013
Authority: CN
Inventors: 彭继增
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-07-13
Filing date: 1998-07-13
Publication date: 1998-12-30
Anticipated expiration: 2018-07-13
Also published as: CN1067962C

Abstract

A process for preparing iron polychloride used to purify industrial water and drinking water includes acid pickling powdered iron ore or waste iron wire with the mixed acid (sulfuric acid and hydrochloric acid) for acceleration and regulating pH value, and features high reaction speed, saving energy, high flocculability, simple process and low cost.

Description

Method for producing poly ferric chloride

The invention relates to a method for producing a flocculating agent, in particular to a method for producing polyferric chloride.

In the water treatment agent, the flocculating agent made of the ferric salt polymer has development prospect in terms of performance, application range and price, but the ferric salt purifying agent used for purifying water is not much. Ferrous sulfate, ferric trichloride, polymeric ferric sulfate, etc. The more elements contained in the chemical structure, the better the flocculation performance of the flocculant, and the flocculation performance of the flocculant can be improved by adding structural water into the original chemical structure. A flocculating agent of ferric polysulfate (Fe) (Fe is published in the handbook of chemical products of Jiangsu province, compiled by the scientific and technological information center of petrochemical industry, Inc., of Jiangsu province) on page 450₂(OH)_n(SO₄)_3-2/n〕_mIt is a new-type inorganic macromolecular broad-spectrum mixed flocculant, and in the course of raw water treatment, it is faster than general aluminium salt and iron salt coagulants in hydrolysis speed, and its flocculation alum blossom initial-growth time is short, and the specific gravity of alum grain is large, and its sedimentation speed is fast, and its raw water turbidity removing capacity is strong, and after treatment, its water quality is good, and its treatment cost is low. The preparation method is to prepare the product by using ferrous sulfate through catalytic polymerization. But the raw material of the ferric polysulfate is ferrous sulphate which is a chemical product and has higher price; certain energy is consumed during the catalytic polymerization in the production process; the chemical structure of the product is simple, and only hydroxide radical and sulfate radical are used for removing iron.

The invention aims to provide a novel flocculant poly ferric chloride, which has lower price and does not consume energy in the production process compared with poly ferric chloride; the chemical structure of the product is more complex than that of the ferric sulfate, and the flocculation performance is improved.

The invention is realized according to the following technical scheme. The production process comprises the steps of carrying out acid leaching on iron ore powder or waste iron by adding hydrochloric acid into sulfuric acid, adjusting the pH value to prepare liquid poly-ferric chloride, and then spraying and drying the liquid to obtain a solid product. The raw material of the method adopts iron ore powder or waste iron, the price of the iron ore powder or waste iron is lower than that of ferrous sulfate, the iron ore powder or waste iron is easy to obtain, the concentration of the used sulfuric acid and hydrochloric acid is not limited, the concentration of the sulfuric acid can be lower than 60 percent, the concentration of the hydrochloric acid can be lower than 20 percent, even the waste acid can be used, and the cost is reduced from the raw material. The method adopts mixed acid for acid leaching, and because the chemical reaction speed of a single acid is low, iron and concentrated sulfuric acid are not easy to react, but the iron and the concentrated sulfuric acid are easy to react, and the reaction is more violent after hydrochloric acid is added. The pickling reaction is exothermic, and the temperature of the product is maintained to be not more than 70 ℃ by means of the exothermic reaction, preferably 50-70 ℃, and the temperature is the most ideal temperature for polymerization after pickling, so that structural water is brought into the product, and the purpose of polymerization is also achieved. The reaction formula is as follows:

or is or In the reaction, iron and sulfurThe ratio of the acid to the hydrochloric acid is 224: 98: 73-292.

The raw material is acid-leached with mixed acid, so that a large amount of gas is discharged, and the acid-leaching reaction must be carried out in a pressure-bearing reaction kettle with a stirrer, because the initial raw material is solid. Because the mixed acid has very violent reaction during acid leaching, a method of adding solid raw materials in batches is adopted to prevent materials from overflowing during the reaction. 1/5 of the weight of the raw materials is added for the first time, when the reaction is not too violent, the pressure is reduced, and the feeding hole is opened; feeding for the second time, wherein the feeding amount is 2/5, and discharging the generated material into auxiliary equipment after pressure drop; and (3) feeding for the third time, namely, completely feeding the residual materials into the auxiliary equipment, wherein the concentration of acid in the materials is not high, the reaction is slow, and the materials are powdery and are stirred. The secondary acid leaching of the materials in a reaction kettle is carried out for more than 1 hour each time. The time required in the auxiliary equipment is increased to 15 to 30 hours. The acid leaching is carried out at 20-70 ℃, preferably 50-70 ℃, so that structural water is easy to be brought in during the reaction. Because the attraction between the components (molecules or atomic groups) in the polymer is larger than the kinetic energy of the movement of water molecules at a lower temperature, the water molecules are easily pulled by the molecules or atomic groups in the polymer and are remained in the polymer, and the product obtained by acid leaching with mixed acid has a complex structure and large molecules. Iron polysulfate [ Fe₂(OH)_n(SO₄)_3-3/nMonomer molecules having only two iron elements, n hydroxide and 3-3/n sulfate, and iron polychloride [ Fe]₄(OH)_2(n-1)(H₂O)_ySO₄Cl_2(6-n)〕_mBesides the above components, the polymer also has 2(6-n) chloride ions and a plurality of water molecules with structure, the polymer molecules are relatively large, the chain is also long, and the performance is improved.

Adjusting the pH value to 1-2 by using 60% sulfuric acid. Thus, the outer layer of the polymer has y sulfate ions, the ions have strong water absorption and are easy to hydrolyze, the sensitivity is high when the ions are mixed with water, and the flocculation is large and the sedimentation is fast during purification. In the above formula, n is 2 to 4, m is 1 to 5(m represents a polymerization degree), and y is determined by adjusting the PH.

The acid-leached material is a pasty colloid which is not easy to separate, and one method is to dilute with a large amount of water, remove the redundant water after filtration and heat and concentrate, thus damaging the structural water and consuming energy. The method of the invention adopts a method of adjusting the PH value by adding acid, so that the residue of the product after acid leaching is quickly separated from the generated mother liquor, the structural water in the polymer is not damaged, and the energy consumption caused byheating and concentrating is avoided.

In conclusion, ore powder or waste iron is used as a raw material, and the mixed acid is used for acid leaching to accelerate the reaction, so that waste acid can be used, and the cost is reduced; because structural water and elements in the product are increased, the molecular structure is complex and large, and the flocculation performance is improved; does not need concentration and heating, saves energy and does not damage structural water in the molecular structure. The product is suitable for treating industrial sewage and drinking water.

The following examples are given for illustration purposes:

example 1, a 2000 ml enamel reactor was charged with 77 ml 30% hydrochloric acid, 63 ml 60% sulfuric acid, 50 ml water, 40 g hematite powder (diameter not more than 1 mm) with a content of 80%, the vessel was sealed, the stirrer was opened for acid leaching, and the pressure dropped significantly after 40 minutes. The charging port was opened, 80 g of hematite powder was added, and after 35 minutes and pressure was reduced, the mixture was poured into a 500 ml beaker, and 80 g of the remaining iron ore powder was added to the beaker. Sealing the top cover, stirring once every half hour, after 18 hours, adjusting the pH value of the material to 2.1 by using 60% sulfuric acid, slightly standing and precipitating (about 10 minutes), separating residues from mother liquor, pouring out the mother liquor on the upper layer to obtain 150 ml of a polyferric chloride liquid product with the specific gravity of 1.42, and keeping the temperature at 50-70 ℃ in the process.

Example 2, a 2000 ml enamel reactor was charged with 130 ml 30% hydrochloric acid, 109 ml 60% sulfuric acid, 100 ml water and 250 g wire cut-off added in three portions to the mixed acid. Adding 50 g of theiron wire for the first time, stirring the mixture evenly by using a stirrer, adding 100 g of the iron wire for the second time, and adding the rest of the iron wire for the third time. Adding iron wires for the first time and the second time, carrying out acid leaching for 0.5 hour each time, adding iron wires for the third time, and standing for 16 hours. The reaction kettle is opened, the whole material is poured out to be sticky colloid, and the PH value is adjusted to be 2 by using sulfuric acid, so that 300 ml of liquid polyferric chloride with the specific gravity of 1.45 and the PH value of 2 is obtained. In the process, the temperature is kept between 50 and 70 ℃. And spraying and drying the liquid product to obtain a solid product.

Example 3

Adding 122 ml of 18 percent by-hydrochloric acid and 123 ml of 50 percent waste sulfuric acid into a 2000 ml enamel reaction kettle, adding 200 g of waste iron wires, covering and sealing the reaction kettle, reacting for 3 hours, pouring the materials into auxiliary equipment together, continuing to react for 15 hours, wherein the materials are viscous colloid, and adjusting the pH value to be 2 by using 60 percent sulfuric acid to obtain 240 ml of liquid polyferric chloride with the specific gravity of 1.43. And carrying out spray drying on the liquid product to obtain a solid product. The temperature was maintained at 50-70 ℃ during the process.

Claims

1. The method for producing the poly-ferric chloride is characterized by comprising the following steps: the solid raw materials of iron ore powder or waste iron and the like are subjected to acid leaching by sulfuric acid and hydrochloric acid, and the PH value is adjusted to prepare a liquid product.

2. The method for producing poly iron chloride according to claim 1, characterized in that: and spraying and drying the prepared liquid product at 50-70 ℃ to obtain a solid product.

3. The method for producing poly iron chloride according to claim 1, characterized in that: the acid leaching step is to add the raw materials into the acid liquor for several times, stir for 1 hour after each feeding, and stand for 15-30 hours after the last feeding and stirring, wherein the temperature is kept at 20-70 ℃, and the optimal temperature is 50-70 ℃ in the whole process.

4. The method for producing poly iron chloride according to claim 1, characterized in that: the acid leaching step is that the waste iron wire raw material is added into waste sulfuric acid with the concentration lower than 60 percent and side hydrochloric acid with the concentration lower than 20 percent, the sealing reaction is carried out for 3 hours, then the material is poured into auxiliary equipment and stands for 15 to 30 hours, and the pH value of the solution is adjusted to be 2 by using the sulfuric acid with the concentration of 60 percent.