CS199180B1 - Borax preparation by alkaline decomposition of ulexite - Google Patents

Description

The invention relates to a process for the production of borax by alkaline decomposition of complexity with a hot solution of sodium carbonate and bicarbonate having a molar ratio of NaHiCO3: NagCO2 in the range of 0.1 to 100%. Increased filterability of the precipitated calcium carbonate.

Borax (sodium tetraborate decahydrate - Νβ ₂ Β ^ Ογ.1Ο HgO) can be produced by a number of technological processes, the most practical of which are currently achieved by the following technological processes:

direct processing of raw materials the basic constituent of which is sodium tetraborate; these auroviruses dissolve in warm or hot water, freeing insoluble components by filtering, sedimenting or removing them; the resulting sodium tetraborate solution is optionally subjected to further chemical cleaning if necessary and, after removal of undesirable impurities, the clear solution is concentrated by evaporation, cooled and crystallized; in this way, the following can be processed from boron raw materials: tinkal - N @ 8 B @ .beta. 5 HgO, kernit-lagB 4 O 2. .4 HgO a ped;

neutralizing the boric acid with sodium hydroxide or a carbonate or sodium bicarbonate; this process is economically costly and is used only for the preparation of technically pure borax;

199 180 alkaline decomposition of calcium, magnesium-calcium and soda-lime polyborates or borosilicates by means of hot solutions of sodium carbonate and bicarbonate 5 in this way it is possible to process from boron raw materials:

aroundanite - calcium hexaborate 2 CaO. 3 ^ O ₃ . 5 ^ 0, ulexlt - calcium decahydrate Ba ^ O. 2 CaO. 5 BgOj. M ®2® 'Hydroboraoite - Calcium Magnesium Hexaborate MgQ. CaO. 3 BgO4. ® ^H 2 ° 'danburite - calcium borosilicate CaO. BgO ^. SiQg, datolite - dicalcium borosilicate 2 CaO. BjCj. 2 SiOg. HgO and others.

In the treatment of boron raw materials by alkaline decomposition with hot solutions of sodium carbonate and bicarbonate, the calcium and magnesium present are removed in the form of insoluble carbonates, possibly calcium or magnesium silicates. The nature of the precipitates formed is strongly dependent on the composition and crystalline structure of the starting materials, which is due to the size of the primary particles formed. Particularly when ulexite is used, a very fine, difficult to filter and sedimentable precipitate is formed. Also, during the processing of borosilicates, fine and poorly filterable precipitates are formed. The formation of poorly filterable precipitates greatly reduces the efficiency of the production equipment and at the same time leads to considerable losses of B ₂ ° 3 ^{in the} waste sludge due to their difficult washability. For these reasons, the attention of the borax manufacturers focuses mainly on the processing of aroundanite and hydroboracite.

On the other hand, the use of ulexite as a basic raw material for the production of borax by alkaline decomposition with hot solutions of Na ₂ CO-j and NaHCO 3 has many advantages over the use of other boric raw materials, in particular:

ulexlt already contains a number of sodium components in its molecule, which can be used effectively in the production of borax, which results in a reduction in the consumption standards of sodium carbonate and bicarbonate per weight unit of produced borax. For example, compared to the use of aroundanite and hydroboracite by up to $ 40, due to the lower proportions of calcium, magnesium and silica present, the weight unit B ₂ 0j in Ulexite Compared to other boric raw materials (aroundanite, hydroboracy, dahburite, datolite etc.) the absolute amount of solid waste per tonne of borax produced, the rate of degradation of the complexity also depends on the composition and crystallographic structure, but is higher for the complexity than other boric raw materials, which favorably affects the performance of the decomposition equipment.

However, the poor filterability of the precipitated calcium carbonate during the processing of the complexity makes its use as a basic raw material for the production of borax by alkaline decomposition difficult to control or even impossible to carry out at all.

The above drawbacks have no method of producing borax by alkaline decomposition of the complexity with a hot solution of sodium carbonate and bicarbonate with a molar ratio of NaHCO 3:

In the range 0.1: 1 to 2 with an increased filterability of the precipitated calcium carbonate according to the invention, it consists in adding 0.01 to 20.2 kg of flocculant for the alkaline medium to the decomposition zone. tons of produced borax. The flocculant s® is added in the form of its scientific solution or suspension to the fresh decomposition; ·. of a carbonate and bicarbonate solution just prior to the actual decomposition. It is an advantage of the invention that the flocculant acts favorably directly on the formation of larger primary particles and at the same time leads to their further agglomeration into secondary particles. As © flokulaat, some of the common flocculants available on the market can be used. Optimal quantity. The amount of flocculant used for a given consignment of raw material must always be experimentally verified and its amount is usually in retouch of 0.01 to 0.2 kg per 1 ton of produced borax. MgCO-j and decompose the obtained slurry is then much easier to filter. This also allows the precipitate to be thoroughly washed, thereby achieving a higher degree of utilization of the base material.

The process according to the invention thus makes it possible to exploit the advantages of the abovementioned advantages of processing complexity which have not been practically possible until now. '

In addition to the advantages mentioned above, the present invention has the further advantage that the sludge, calcium carbonate, due to the possibility of better washing, contains substantially lower contents of &_lt; _{2 &} gt ^; < ³ > challenging. All of the above benefits contribute favorably to reducing production costs.

The following are some examples of borax preparation from ulexite:

Example 1

2500 kg, finely ground ulexite containing 40% BgOj is boiled for 2 hours at normal atmospheric pressure or in an autoclave under pressure up to 0.6 MPa with a decomposition solution of carbonate and sodium hydrogen carbonate {molar ratio NsHCOy: Na ₂ C0j » 1.1: β 1.0) in an amount corresponding to a total Na content of 218 kg (ie 282.5 kg NaHCO 3 and 324 kg NagCO 3). 10 L of a 1% flocculant solution was added to the fresh hot sodium carbonate / bicarbonate solution just before use. The decomposed residue and the resulting calcium carbonate formed by the reaction are filtered off from the obtained suspension after decomposition. The clear sodium borohydride solution obtained is evaporated, the concentrated solution is rapidly cooled to below 50 DEG C. and crystallized.

The filtration rate of the undecomposed residue and of the precipitated CaCO 3 was using flocculanes 3.5 times higher than without it.

IN

Example 2

2500 kg Finely ground complexity containing 40% ^Β 2θ3 ^ββ P ° for 2 hours from normal atmospheric pressure or in an autoclave under pressure up to 0,6 MPa β with a decomposition solution of sodium carbonate and sodium bicarbonate (molar ratio NrHCO-j NagCO ^ 1) , 3 ϊ 1.0) in an amount corresponding to the total content of Na 218 kg (ie 313.8 kg NaHCO 3 and 304.5 kg NagCO 3). To the fresh solution to be added, NaHCO 3 and NagCO 3 are added just prior to use of liters of a solution containing 5 g / liter of flocculant. The decomposed residue and the resulting calcium carbonate formed by the reaction are filtered off from the obtained suspension after decomposition. The resulting sodium sodium borohydride solution was evaporated and the concentrated solution was rapidly cooled to below 50 ° C and subjected to crystallization.

The filtration rate of the obtained decomposition sludge β by the addition of flocculant increased 3.78 times that of the filtration performed without the addition of flocculant.

Example 3

2500 kg of finely ground complexity containing 40% ^B 2 ° 3 ^{80 for 2} hours at atmospheric pressure or in an autoclave under a pressure of up to 0.6 MPa and a decomposition solution of carbonate and sodium hydrogen sulphite (molar ratio NaHCO 3: NgCO 3 = 2.0) to 1.0) in an amount corresponding to a total Na content of 218 kg (i.e., 398 kg NaHOO? and 250.8 kg NSgCO3).

To the fresh hot solution of NaHCO 3 and Na 2 O 4 added is added just before the use of liters of a lazy flocculant solution. The unreacted residue and the calcium carbonate formed by the reaction are filtered off from the obtained suspension after decomposition. The clear sodium tetraborate solution obtained was evaporated, the concentrated solution was rapidly cooled below 50 ° C and crystallized.

The filtration rate of the obtained decomposition slurry with the addition of flocculant ss increased by 2.96x compared to the decomposition without addition of flocculant.

Claims (1)

A process for the production of alkaline alkali metal salt and hot sodium carbonate and bicarbonate with solar porosrea NaHCO 3 with MagCO 2 in a 0.1 to 1: 2: 1 ratio, with increased filterability of the precipitated calcium carbonate, rendered difficult to resist sony add 0.01 to 0.2 kg of flocculant for alkaline water and 1 ton of borax produced.