WO2010140989A1

WO2010140989A1 - Production of boric carbonate and sodium bicarbonate from sodium borate solvents

Info

Publication number: WO2010140989A1
Application number: PCT/TR2009/000110
Authority: WO
Inventors: Orhan Yilmaz; Fehmi Unlu; Goknur Karakoc; Derya Maraslioglu; Soner Gokcek; Ebru Karacay; M. Hamdi Demirhan; C. Emrah Cetin; Omer Iplikcioglu
Original assignee: ETI MADEN ISLETMELERI GENEL MUDURLUGU
Current assignee: ETI MADEN ISLETMELERI GENEL MUDURLUGU
Priority date: 2009-06-05
Filing date: 2009-08-26
Publication date: 2010-12-09
Anticipated expiration: 2011-12-05
Also published as: TR200904415A2

Abstract

This study aims to obtain a new sodium saline consisting of carbonate and bore to ensure easy to use in industrial sectors using sodium carbonate and sodium borate together and also to use as raw material the CO₂ gas which is the most important greenhouse gas damage of which has been felt much more recently and causing global warming and thus to reduce the CO₂ gas emission emitted into environment. For this the invention relates to a new product (boric carbonate) obtained by means of passing CO₂ (carbon dioxide) gas through the diluted solvents of sodium borate by use of autoclave (1) (high pressured and temperature reactor) jacket reactors (4) and gas absorption column (7) systems and also to obtaining pure carbonate as a result of extraction of the said product by methyl alcohol.

Description

PRODUCTION OF BORIC CARBONATE AND SODIUM BICARBONATE FROM

SODIUM BORATE SOLVENTS

DESCRIPTION

The invention relates to a new product (boric carbonate) obtained by means of passing CO₂ (carbon dioxide) gas through the diluted solvents of sodium borate produced from all-in concentrated and calcined tincal by use of autoclave (1) (high pressured and temperature reactor) jacket reactors (4) and gas absorption column (7) systems and also to obtaining pure sodium bicarbonate as a result of extraction of the said product by methyl alcohol.

Having considerably rich sodium borate reservoirs, Turkey markets these products as refined products and also converts them into new products and aims to contribute to consumption of products based on boron and thus development of the boron industry. This study aims to obtain a new sodium saline of carbonate and boron content. Thus it will be possible to provide highly easy to use in industrial sectors using particularly sodium bicarbonate and sodium borate together.

The 5 and 10 hydrated forms of Borax are the most important commercial forms of Borax. Borax decahydrate (Na₂B₄O₇-IOH₂O) is a sodium borate hydrate of monoclinic crystal structure with 1,715 g/cm³ density. Borax pentahydrate (Na₂B₄O₇.5H₂O) is a sodium borate hydrate of trigonal structure with 1,880 g/cm³ density. Commercial borax pentahydrate generally contains 4,67 mol water. Some of concentrated tincal is used for production of borax pentahydrate. The pH of borax solvents is almost independent of concentration and varies between 9,2-9,5. The solubility of borax increases with increase in temperature and solubility curves of penta and deca- hydrates intersect at about 60,6 ⁰C and 60,8 ⁰C . From here, it is understood that in case the saturated borax at 100⁰C is cooled to 60⁰C, borax pentahydrate is crystallized and in case of repeating the same process at lower temperatures, borax decahydrate is crystallized.

The second raw material used in the study is CO₂ gas, which has been felt much more recently and one of the most important greenhouse gas causing global warming, It is a gas having a rich and wide range of use in several industries due to its multi purposed features and capable to dissolve in water and indicating acidic feature. Other physical features of the CO₂ gas has been given below and it is heavier than air; is odorless and colorless, may convert into solid form at atmospheric pressure and is in liquid form under pressure. It does not support flaming.

Molecule weight : 44.01 g/ mol

Density (liquid, at -56,6 ⁰C) : 1 , 1778 kg/ m³

Density (gas, 0 ⁰C, 1 atm) :1 ,97 kg/ m³

Critical temperature (1 atm) :31 , 1⁰C Sublimation temperature : : -78,5O⁰C (from solid phase to gas phase)

Specific gravity (air : 1 ) : 1 ,528

When searching the literature regarding the passing CO₂ gas through boric saline containing sodium, it is seen that in a study for production of boric acid by CO₂ gas reaction with sodium containing boric acids under the scope of a boric acid production process developed by United States Borax and Chemical Company in 1959, sodium borate solution of Na₂OVB₂C₃ rate at range of 0.3:1-0.38-1 molar weight was prepared, water was added to the water at the required quantity needed under the frame of stocyometric requirement for CO₂ (carbon dioxide) and sodium borate reaction and the solution temperature was increased and decreased at the range of 25 ⁰C - 75 ⁰C and CO₂ pressure between 30 Ibs/sqinch - 615 Ibs/sq. inch with the same logic, and sodium bicarbonate crystals were obtained at high temperature and CO₂ pressure, that boric acid crystals were obtained were obtained at relatively lower temperature and CO₂ pressure, that sodium borate was added at each cycle and that boric acid production was made from sodium borate and CO₂ water solutions (Boric Acid production US Patent No 3,031,264 or British, UK861,416). The same method was used in the study made by Yϋcel H. in his Master Thesis and the conversion reaction is as follows (Karbonasyon ile Sodyum Tetiaborat dan, Borik Asit ve Sodyum Bikarbonat Uretimi (Production of Boric Acid and Sodium Bicarbonate from Carbonation and Sodium Tetiaborate), Yϋksek Lisans Tezi (Master Thesis), Hayrettin Yϋcel, 1973)

Na₂B₄O₇.nH₂O + (7-n)H₂0 + 2CO₂ ► 2NaHCO₃ + 4H₃BO₃

In the patent of boric hydride component synthesizing process granted to Steven C. Amendola et al. in 2003, NaHCO₃ and B₂O₃ production is in a reactor convenient for mixing with heated jacket by applying the room temperature between 175 - 200 ⁰C, preferably 200 ⁰C, CO₂ pressure between 10 - 750 psi [0.68 - 51 atm] preferably 30 - 40 atm .

4NaBO₂ + 4CO₂ + H₂ O ⁴ 4NaHCO₃ + 2B₂ O₃

In addition to these studies, there are also studies about production of sodium carbonate from reactions of sodium borate saline, ammonium bicarbonate (Sodium bicarbonate and boric acid production from sodium Boron, US Patent No 4.022871 , 10 May 1977) and methanol ({5} Boron Esters preparation, US Patent No 2,884,440, April 1959).

Figures and Parts

Figure 1 . Boric carbonate production in Autoclave (1) system

Figure 2 . Boric carbonate production in Jacket Reactor (4) system Figure 3 . Boric carbonate production in Gas Absorption Column system

Part Reference No.

1. Autoclave (1 ) (20-75 ⁰C and -20-800 psi)

2. Filter

3. Dryer (30-40 ⁰C)

4. Jacket Reactor

5. CO₂ gas supply line

6. Cryostat (50-60 ⁰C)

7. Gas absorption column

8. Tank

9. Heater (45-70 ⁰C)

Sodium carbonate and boron containing new products are obtained from reaction of water solutions prepared from sodium borates with CO₂ gas. These products are used as new products depending on their consumption area and can also be classified as sodium carbonates and borates. Different systems have been used in realization of the reaction and the formation parameters of the product according to the systems have been specified.

1. Boric carbonate production in Autoclave (1 ) system

Process flow chart is shown in Figure 1. The study has been conducted in an autoclave (1) device of 1 It capacity and 500 °C temperature, 300 atmospheric pressure and 1500 cycles/minute mixing rate in our laboratories and the it is likely to take sample in the reactor at any time interval. Reaction equation:

Na₂B₄O₇ + 6H₂O + 6/5 CO₂ _ 6/5 NaHCO₃ + 7/5 H₂O + 4/5 NaB₅O₆(OH)₄(H₂O) ₃

Sodium borates of 0.44 and 0.88 molar Na₂0/B₂0₃ rate with weight 3,5% - 2I Na₂O content solvents were prepared and sodium borate products of sodium bicarbonate content of 2 - 80 % and 5 - 44% B₂O₃ were obtained during reaction time of 60-420 minutes, preferably subjecting to the reaction for 120 minutes, 20-800 psi range CO₂ gas pressure, 550 cycle/minute mixing rate and , preferably 12,7% Na₂O content,, temperature of 20- 75 ⁰C preferably 60 ⁰C₁. The carbonate and boron amounts as per the product intended to be obtained depending on area of use can be obtained at the study conditions given in Table 1. The table shows the summary of the conducted studies. Sodium borate solutions to be prepared as per the final product intended to be obtained of % Na₂O by weight are subjected to reaction at the above mentioned temperature, pressure and the duration in the autoclave (1) device. The sludgy article obtained after the reaction time is sent to the filter (2) unit designed according to pressure filtration principle by help of a hose installed at the drainage valve of the autoclave (1) device at 52 - 54 0C and the product filtered at operating pressure is then subjected to filtration with vacuum at the filter (2) unit by applying pressure with CO₂ gas again. The cake contains 7% humidity and is dried in drying oven (3) at 30 - 40 ⁰C. The boric carbonate product obtained in this way also contains sodium borate not entering in the reaction. Although the system is intermittent the obtained solution can be used as feed again and therefore provides recycling process. In this system, sodium borate and NaB₅O₆(OH)₄(H₂O)₃ (sborgite) mixture not entered into reaction is obtained as a side product.

Table 1 - Contents of boric carbonate product formed according to reaction parameters

2. Boric carbonate production in Jacket Reactor system

Process flow chart for the studies conducted at jacket reactor (4) is given in Figure 2. CO₂ gas is fed into the solutions of sodium borate containing 0,44 and 0,88 molar prepared in concentrations of 4,6 - 4,8% Na₂O by weight, by means of a line (5) installed into the jacket reactor (4). Reaction temperature is adjusted by cryostat (6) connected to the jacket reactor (4). The crystals obtained from the sodium borate solution prepared with 4,6 - 4,8 % Na₂O by weight in the study conducted at 50 - 60 C temperature, 12 hours reaction time, under atmospheric pressure and 500 cycles/minute mixing rate are subjected to filtration by vacuuming by filter (2) at -5 - 50 C and dried at drying oven (3) at 30-40 C. The obtained product is sodium bicarbonate of 5-12% and sodium borate of B₂O₃ of 32 -37%. The boric carbonate product obtained in this way also contains sodium borate not entering in the reaction. In this system, sodium borate and NaB₅O₆(OH)₄(H₂O)₃ (sborgite) mixture not entered into reaction is obtained as a side product. The summary of the studies have been shown in Table 2.

Table 2 - Contents of boric carbonate product formed according to reaction parameters

3. Boric carbonate production in Gas Absorption Column system

Study was performed in filled column in order to increase gas - liquid reaction surface area and ensure continuity. Process flow chart is shown in Figure 3. The features of the gas absorption column (7) are as follows.

Column length : 1 meter

Column diameter : 10 cm.

Rasching ring size : 8 x 8 mm. Saturated sodium borate solution containing 0,44 and 0,88 Na₂0/B₂O₃ mol of pH > 9 prepared according to working temperature is located in the feeding tank (8) of the filled gas absorption column (7). The solution in the feeding tank (8) is heated to 45-70 ⁰C, preferably 60 C by means of heater (9). The solution is sent to the upper part of the gas absorption column (7) (from the solution tank at the feeding rate of 400 ml/minute - 1500 ml/minute, preferably 1000 ml/minute by means of peristaltic pump, and flows downward from column over filling surface and absorbs CO₂ gas. Recycling of the solution from lower part is provided. 0,5 - 1 bar CO₂ gas and air mixture is sent upward in reverse direction from lower part of the absorption column (7). This cycling is continued for 240-480 minutes by adding sodium borate solution to the system in order to ensure pH >8 . The solution obtained at the end of the reaction duration is transmitted to jacket reactor (4) and subjected to crystallization at temperature range of 5 - 50 ⁰C. The crystals formed in the solution are vacuumed at filter (2) unit ^"and subjected to filtration. The obtained product crystals is dried at drying oven (6) at temperature range of 30 - 40 °C.

Reaction occurring conditions Temperature (⁰C) : 45 - 70

Solvent pH : 7,6-9,5

CO₂ gas supply (bar) : 0,5 - 1

Reaction duration (minute) : 240 - 480

Na₂O/B₂0₃ (%) : 0,44-0,88 The obtained boric carbonate content consists of sodium borate of 30 - 37% B₂O₃ value and sodium bicarbonate of 3-25%.

In this system, sodium borate and NaB₅O₆(OH)₄(H₂O)₃ (sborgite) mixture not entered into reaction is obtained as a side product

Obtaining Pure Carbonate from Boric Carbonate

The boric carbonate product obtained from autoclave (1), jacket reactor (4) and gas absorption column (7) systems is pure carbonate obtained by extraction process by use of dissolution of the products in different solvents.

The feature of borate to dissolve in methyl alcohol has been used for extraction process. To achieve it, 5% more methyl alcohol than the dissolution value of borate in methyl alcohol in the product at 30 ⁰C has been added and mixing has been applied for 1 hour and the obtained solvent has been subjected to filtration. The cake obtained as a result of the filtration is 98-99% sodium bicarbonate with 87% efficiency.

Claims

1. The invention relates to obtaining boric carbonate product, wherein, it comprises of process steps of preparation of sodium borate solutions containing 3,5 - 21 % Na₂O by weight at autoclave (1) (preferably 12,7% Na₂O), treatment with CO2 at temperature of 20 - 75 ⁰C (preferably 60⁰C), for 60-420 minutes (preferably 120 minutes), at 550/cycles/minute mixing rate, under 20-800 psi pressure and then filtration at temperature rate of 52 - 54 ⁰C and at working pressure and vacuuming with CO2 gas at filter (2) unit again and subjecting to filtration to obtain cake of 7%≤ humidity content and drying the crystals at temperature range of 30 - 40 ⁰C (preferably 30 ⁰C ) at drying oven (3).

2. Sodium borates according to claim 1 , wherein, sodium borates comprise B₂O₃ at range of 5-44% and sodium bicarbonate at range of 2-80%.

3. A method for obtaining boric carbonate wherein, it comprises of process steps of preparation of sodium borate solutions containing 4,6 - 4,8 % Na₂O by weight, supply of CO₂ gab under atmospheric pressure into gas supply line (5) installed into jacket reactor (4), subjecting to reaction at 500 cycles/minute mixing rate, at temperature range of 50 - 60

⁰C for 12 hours, transfer of the obtained products to the jacket reactor (4), subjecting them to crystallization at temperature range of 5 - 50 ⁰C , vacuuming at filter (2) unit, subjecting to filtration and drying at temperature range of 30 - 40 ⁰C (preferably 30 ⁰C ) at drying oven (3).

4. Sodium borates according to claim 3, wherein, sodium borates comprise B₂O₃ at range of 32-37% and sodium bicarbonate at range of 5-12%..

5. A method for obtaining boric carbonate product wherein, it consists of process steps of preparation of sodium borates of pH > 9 saturated solvent at 45-70 C (preferably 60 C), and passing air from upper part of the saturated gas absorption column (7) at 400-1500 ml/minute(preferably 1000 ml/minute) and CO2 gas at 0,5-1 bar (preferably 1 bar) mixture from lower part for 6-8 hours (preferably 6 hours), transfer of the obtained product to jacket reactor (4), subjecting it to crystallization at temperature range of 5 - 50 ⁰C, vacuuming the obtained solution and crystal mixture at filter (2) unit, subjecting it to filtration and drying crystals at temperature range of 30 - 40 ⁰C (preferably 30 ⁰C ) at drying oven (3).

6. Sodium borates according to claim 5, wherein, sodium borates comprise B₂O₃ at range of 30-37% and sodium bicarbonate at range of 3-25%.

7. Sodium borates according to claims 1 , 3 and 5 wherein sodium borates contain 0,44 and 0,88 Na₂0/B₂O₃ mol rate.

8. A part of sodium borate not entering into reaction under claims 1 , 3 and 5 is also present in the boric carbonate formed after reaction.

9. The products obtained under claims 2, 4 and 6 are boric carbonate products and they consist of NaHCO₃ (sodium bicarbonate), and sodium borate mixtures not entering into reaction.

10. The side products produced according to claims 1 , 3 and 5 wherein they are sodium borate and NaB₅O₆(OH)₄(H₂O)₃ (sborgite) mixture not entered into reaction.

11. 5% more methyl alcohol than the dissolution value of borate in methyl alcohol in the boric carbonate product obtained under claims 3, 5 and 6 is added at 30 ⁰C and mixed for 1 hour and the obtained solvent is subjected to filtration and dried at drying oven (3) at 30 ⁰C and thus 87% efficient and 99% pure sodium bicarbonate is obtained.