WO2022045988A1

WO2022045988A1 - Method of production of ferric chloride solution by induction heating of solid iron

Info

Publication number: WO2022045988A1
Application number: PCT/TH2020/000080
Authority: WO
Inventors: Pitaya Yangpichit
Original assignee: Pitaya Yangpichit
Priority date: 2020-08-24
Filing date: 2020-12-08
Publication date: 2022-03-03
Also published as: CN116057013A

Abstract

Production of an aqueous solution of ferric chloride which can be produced in various concentrations and therefore subsequently used for different purposes. The ferric chloride solution is produced in an array of three reaction chambers. In the first chamber (C1) a mainly ferrous chloride containing solution reacts under a chlorine atmosphere with a heated solid iron surface to increase its concentration. A second chamber (C2) then neutralizes the pre-concentrated ferrous/ferric chloride solution, which contains small amounts of hydrochloric acid. The third and final reaction chamber (C3) ensures the transformation of ferrous-into ferric chloride solution by the reaction of ferrous chloride under a chlorine atmosphere until the product achieves the final quality of its desired application.

Description

METHOD OF PRODUCTION OF FERRIC CHLORIDE SOLUTION BY INDUCTION HEATING OF SOLID IRON

Summary of the invention

The above described traditional processes of the production of a ferric chloride solution of certain quality varies deeply from this new invention of producing a ferric chloride solution in such, that this new invention does not require iron to be submerged and heated from the outside of the reaction chamber. Instead, only the iron will be inductively heated to react with the other reactants in an “inside-out” manner in order to create a final ferric chloride solution of controllable and distinct concentration. This inventive feature allows one to produce at higher speeds than usual. The iron must not be submerged during the reaction and therefore permits one to choose other nonmagnetic construction materials for the chemical production process. This arrangement enables iron temperatures to be higher than the temperature of all surrounding production process equipment and the liquids themselves.

Background of the invention

1. Field of the invention

The invention relates to the production of aqueous ferric chloride solutions, suitable for various industrial applications, especially as a flocculant in the water treatment industry.

2. Description of the prior art

The basic and most common process of producing an aqueous solution of a distinct ferric chloride solution is the reaction of a ferrous-/ferric chloride solution of low concentration, such as “spent acid” or “spent liquor” together with iron in the form of chips, grains or scrap, mainly from the steel industry. These basic combinations react with hydrochloric acid and under a chlorine gas atmosphere to develop the distinct product. Such a process is outlined by E.T. Ladd in Pat. US 2,096,855, page 2, line 74, where solid iron is submerged in a tank containing ferric chloride.

The use of ferric chloride solutions especially as flocculants in the water treatment industry is quite common. See also the following Patents: US 4,066,748, US 5118489 and US 5547637.

To achieve higher efficiencies of the above described common and usual production process, it sometimes requires additionally variable physical inputs like pressure, vacuum and/or elevated temperatures and cooling: See also Patent US 5547637 “DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION”

Brief description of the drawings

The drawing illustrates the production process of ferric chloride solution schematically.

It reflects the very basic equipment arrangement needed to produce the in this invention described ferric chloride solution.

Chambers (Cl), (C2), (C3) are chemical reaction chambers. Chamber (Cl) and (C2) are equipped with external induction heaters (Hl) and (H2). All chambers are fitted with flow heads (SI), (S2) and (S3), to enable the flow of solution over the iron surface in chamber (Cl) and (C2) and over the packing (Rl) in chamber (C3).

The large pipes (Pl) and (PIO) are supply pipes for solid iron (Ml) and (M4). Pipe (P5) supplies pickling liquor (3) to pipe (P3) which is connected to chamber (Cl). Pipe (P4) of chamber (Cl) is connected to an air scrubber (M2). A hydraulic seal (H) is attached via pipe (P9) to chamber (C2).

Pipes (P2), (P3), (P6), (P7), (P8), (Pl 1), (P12), (P13), (P14), (P15) together with the pumps (Al), (A2), valves (VI), (V2), (V3), (V4), (V5), (V6), (V9), and back flow valves (V7) and (V8), belong to the network of supply, recycle and storage pipes for the regulation of the liquid and gaseous flow of the process reactants

Pipe (Pl 6) on the hydraulic seal (H) vents off hydrogen gas.

Detailed description of the embodiments of the invention

This invention is aimed to produce a ferric chloride solution from pickling liquor of at least commercial quality by the following process:

A three-chamber arrangement of chemical reactors is the production base to produce the said ferric chloride solution.

The first reactor maintains the continuous reaction of solid iron (Fe) in various forms such as scrap, pellets, bars etc. in the presence of a ferrous chloride solution from industrial pickling processes and chlorine gas to finally react to a solution which contains at least 14% of iron (Fe).

The second reactor neutralizes the remaining free acid of the solution, which developed during the reaction in the first chamber, to less than 1% by reacting with solid iron (Fe).

The third reactor is fed with chlorine gas and the solution from chamber two in order to chlorinate the mainly ferrous chloride solution into a ferric chloride solution of at least 42% concentration. In detail the reactors one and two allow to recycle the solution by spraying, rinsing or flowing it multible times over the solid iron (Fe).

In reactor one and two, the solid iron (Fe) is heated from the outside by induction, causing the solid iron (Fe) inside the reactor to reach temperatures, which basically allow the liquid flowing down over the heated solid iron (Fe) to digest it.

In reactor one, this treatment assures the inevitable very fast reaction between all the three reactants solid iron (Fe), ferrous chloride and chlorine gas according to equation (1)

Fe + FeC12 + C12 -> 2FeC12 (1)

In this reaction, solid iron (Fe) is forced to react due to its high temperature and therefore being vigorously digested by the other reactants as the digesting rate is a function of temperature. The higher the temperature the faster the digestion will be.

Production process in detail:

Solid Iron (Fe) of different sources and nature (Ml) is filled into chamber (Cl). Pickling liquor (M3) enters via valve (V9) through pipe (P5) the circulating pipe (P3), which enters the chamber (Cl) at the upper part and finally sprays, rinses or flow the solution over the solid iron (Fe) surface while avoiding the solid iron (Fe) to be submerged. During this process chlorine gas enters the chamber at any point through pipe (Pl 2) to create an overall chlorine gas atmosphere inside the chamber. The solid iron (Fe) is then heated by induction heating from the outside of the chamber to a temperature suitable for the most efficient reaction. The reactants exit at the bottom of chamber (Cl) by pipe (P2) and than either being pumped by pump (Al) via valve (V2) of pipe (P3) back into the chamber to be recycled, or via valve (V3), passing the back flow valve (V7) t o chamber (C2) and later chamber (C3) for further treatment.

The solution entering chamber (C2) has at least a concentration of 14% iron (Fe) and exist of a mixture of ferrous-, ferric chloride, water and small amounts of hydrochloric acid. The design of chamber (C2) is similar of chamber (Cl). Chamber (C2) is equipped with an external induction heater (H2) and partially filled up with solid iron (Fe). The solution coming from chamber (Cl) enters the chamber (C2) through valve (V5) and pipe (P8) and flushes down onto the solid iron (Fe) in the chamber (C2). It will exit at the bottom into pipe (Pl l), passing the pump (A2) which maintains the recirculation via valve (V5) and pipe (P8) and/or after adequate reaction as shown in equation (2), pumped directly via valve (V4) and pipe (P15) into chamber (C3).

For this, valve (V5) must be closed and valve (V4) be opened.

During the reaction in chamber (C2) under the influence of heat, parts of the hydrochloric acid will escape as wet fume through the pipe (P9) into the hydraulic seal (H) where it is scrubbed by pickling liquor (M3) supplied via valve (V9) by pipe (P6). The solution is then flowing via valve (VI) and pipe (P7) into pipe (P5). Hydrogen fumes inside the hydraulic seal (H) are vented into the atmosphere via pipe (Pl 6).

In chamber (C3), the ferrous chloride solution is exposed to chlorine gas (M5) which enters the chamber somewhere at the bottom of the chamber (C3) via pipe (Pl 2), passes a packing of raschig rings (Rl) etc., for the change from a ferrous- into a ferric chloride solution of minimum 42% concentration according to the equation (3).

2FeC12 + C12 -> 2FeC13 (3)

The desired solution will then exit the chamber (C3) at the bottom through pipe (Pl 4) to be finally collected and stored as product (M6).

Due to the induction heating in the chambers (Cl) and C2), the heat flow in these chambers is from the center radial to the outside. Which means from the solid iron (Fe) through the liquid into the chambers inner atmosphere and finally to the wall of the chamber, which in this case must withstand the lowest reaction temperature of this chamber and additionally the wet chlorine gas atmosphere of chamber (Cl) only. This generally allows the use of non-magnetic construction materials such as ceramics, thermoplastics, graphite etc., at least for the areas above the bottom of the chambers. Whereas in conventional systems the heat flow is from the outside to the inside of a chamber, which requires a construction material which is highly anti -corrosive and of higher temperature resistantance than that of the invention.

Additionally, and due to this construction arrangement, the efficiency of the production in this kind of process is the highest possible and easy to control by adjusting the temperature of the reactive solid iron (Fe) via the induction heaters (Hl) and (H2), surrounding the chambers (Cl) and (C2).

As the production process needs chlorine gas (M5) in chamber (Cl) to oxidize the solid iron (Fe) and chamber (C3) to transform the ferrous into a ferric chloride solution, it is fed into chamber (C3) through pipe (P12) and leaving the chamber through pipe (P13).

Chlorine gas (M5) is also flowing directly via valve (V6) and back flow valve (V8) through pipe (P12) and the joining Pipe (P13) from chamber (C3) into chamber (Cl) for the start and continuation of the whole production process. Best Mode for Carrying out the Invention

As described above

Claims

6 Claims

1. A method of producing a concentrated ferric chloride solution, comprising the steps of:

A) Passing a thin film of preferrably ferrous chloride solution under chlorine atmosphere over inductively heated solid iron. B) Neutralizing said solution to get rid of remaining hydrochloric acid.

C) Chlorinating said neutralized ferrous chloride solution to convert it into a ferric chloride solution.

2. A method of producing a concentrated ferric chloride solution according to claim 1, where the temperature of said solid iron can be controlled by induction heating.

3. A method of producing a concentrated ferric chloride solution according to claim 1, comprising inductively heated solid iron which by changing the input of electrical current and frequency determines the speed and efficiency of the production process.

4. A method of producing a concentrated ferric chloride solution according to claim 1, where the highest temperature of the production process is within the inductively heated solid iron.

5. A concentrated ferric chloride solution produced by using method as claimed in claim 1