A120 3 + N a2C 0 3 = 2NaAJ02 + C 0 2
X r o m i t n i kuydi ri sh n a t ij as ida o l i n g an n a t r i y
x r o m a t i suv b i lan
ishlanib q o t i s h m a d a n a j ra ti b ol inadi .
N a t r i y x r o m a t i n i n g nat ri y b i x r o m a t i g a o ‘t ka z i s h u c h u n x r o m a t
er it ma s i sulfat kislotasi bil an i shl anadi . Bu j a r a y o n n i ishlab c h i q a
r i shda «travka» d e b a t as ha di :
2 N a C r 0 4 + H 2S 0 4 = N a 2C r 20 7 + N a 2S 0 4 + H 20
S h u n d a y qilib, r e aks ion m as s ag a q o ‘shi lgan s o d a n i n i n g 6 0 % d a n
o r t i q r o g ‘i n a t r i y sulfatiga a y l an ad i . X r o m a t n i b i x r o m a t g a o ‘t kazi sh
u c h u n C 0 2 d a n h a m f oy da la ni sh m u m k i n :
2 N a 2C r 0 4 + 2 C 0 2 + 3 H 20 = N a 2C r 20 7 + N a H C 0 3
X r o m a t xl or b il an h a m ishlash m u m k i n , bu usul ni x l or usuli deb
ataladi:
6 N a 2C r 0 4 + 3C12 = 3 N a 2C r 20 7 + 5 N a S l + N a C 1 0 3
Re a g e nt sifatida ftor v o d o r o d kislotasidan h a m foyda la ni sh m u m
kin:
2 N a 2C r 0 4 + 2 H F = N a 2C r 20 7 + 2 N a F + H 20
2 N a 2C r 0 4 + N a A 1 0 2 + 6 H F = N a 2C r 20 7 + N a 3A l F 6 + 3 H 20
N a t i j a d a x r o m a t n i b i x r o m a t g a i shlash j a r a y o n i d a ftor b i r i k m a l a
rini h a m s i n t e z qilish m u m k i n .
I s hl ab c h i q a r i s h d a n a t r i y b i x r o m a t i q u y i d ag i s x e m a b o ‘y i c h a
ol inadi . Tabi iy x ro mi t rudasi ikki b o s q i c h d a yaxshi lab may d al an il ad i.
Q o l g a n k o m p o n e t l a r — s o d a va d o l o m i t m a y d a l a n a d i . M a y d a l a n g a n
re a ge nt la r s h ne k - a r a l a s h t i r g ‘i chda aralashtiriladi.
Shixt aning tarkibini
s o d a n i n g m i q d o r i s t e x o m e t r i k m i q d o r d a n 5 — 10% k a m r o q , d o l o m i t -
ni ng m i q d o r i C r 20 3 va s o d a n i n g m i q d o r i n i 180—2 0 0 % n i tashkil
qilishi k er a k . S h u n d a y qilib, t a y y o r l a n g a n a r a l a s h m a a v t o m a t i k
r a vis hda ishlab t u r u v c h i t ar oz i or qa l i i shl ovchi p e c h g a y ubor i ladi .
P e c h s i l i n d r i k s h a k l d a a y l a n i b t u r u v c h i a p p a r a t b o ‘lib u z u n l i g i
40 m d = 2 m. Shixt a 3 soat d a v o m i d a p e c h d a pishiriladi. T e m p e -
r a t u r a ni 1100— 1150°C g a c h a k o ‘tarish u c h u n m as sa g a q a r a m a - q a r -
shi issiq g a z v a ok si dl as h u c h u n h a v o y u b o r i l a d i , n at i j a d a C r , 0 3
ni ng 80— 85% C r 0 3 ga a y la n a di . P e c h d a n c h i q q a n q o t i s h m a 8 0 0 —
900°C b il an p a n j a r a g a y ubor i ladi . K a t t a b o ‘l ak c ha l a r i m a y d a l a s h g a
y ubor i ladi .
3 9 2
M a y d a l a n g a n q o t i s h m a k e l ayot ga n t ar ki bi da 2 0 — 50 g r / / N a 2C r 0 4
b o ‘lgan y u v i n d i s u v d a eritiladi ( 8 0 — 85°C). S o ‘n g r a e r i t m a C 0 2 gazi
bil an i shl anadi (saturatsiya). Na t i j ad a kalsiy x r o m a t i
va q i s m a n natriy
a l u m i n a t i p a r c h a l a n a d i . A r a l a s h m a a y l a n u v c h i b a r a b a n v a k u u m -
filtrga y ub or i l i b e r i t m a c h o ‘k m a l a r d a n filtrlanadi. E r i t m a n i n g t a r k i
bi da 170— 180 g / / N a 2C r 0 4 b o ‘kidi. Filtrdagi c h o ‘k m a yuvilib, yuvindi
suv q o t i s h m a n i er iti sh u c h u n y u bo r i l ad i , c h o ‘k m a esa t a s hl an ad i .
E r i t m a s ul f a t kislotasi b i lan q o l g a n nat ri y a l u m i n a t d a n t o z al a n a d i .
2 N a A 1 0 2 + H 2S 0 4 + 2 H 20 = 2 A 1 ( 0 H ) 3 + N a 2S 0 4
Hosil b o ‘l gan A l ( O H ) 3 d a n t o z a l a n g a n d a n s o ‘ng 3 m o n o x r o m a t
er i t masi 4 - k o r p u s l i k v a k u u m - b u g ‘latuvchi a p p a r a t i g a yubori li b 4 3 5 —
485 g / / g a c h a q u yu ql as ht i ri l a di . Q u y u q e r i t m a x r o m a t n i b i x r o m a t g a
o ‘t k a z i s h u c h u n m a x s us q o z o n d a 7 3 —77% sulfat kislotasi b i lan i sh
l an a d i. Bu re aksi ya e k z o t e r m i k b o ‘lgani sababli
sulfat kislotasi as ta-
s eki n quyil ishi kerak. O l i n g a n b i x r o m a t e r i t m a s i ( t a r k ib i da natri y
sulfati) ma x s us b u g ‘latuvchi q o z o n g a yuborilib 7 0 0 —750 g / / N a 2C r 20 7
g a c h a q uy ul tir il adi.
N a t i j a d a nat ri y sulfatning asosiy qismi kristallga ayl ana di va c h o ‘-
kadi, filtr y o r d a m i bilan b ix r o ma t eritmasi N a 2S 0 4d a n ajratib olinadi.
N a 2S 0 4d a n ajratilgan b i x r o m a t 2 - b o s qi c h b u g ‘lani sh q oz o n i g a y u b o
rilib k on s en t ra t s i y a s i 1400— 1500 g / / g a c h a quyuq la s ht i ri l a di .
B u g ‘lati lgan b i x r o m a t e r it m a s i c h o ‘k m a l a r i d a n t o z a l a n i b krist al
lizatsiyaga y u bor i ladi .
B i x r oma t er it masi ma x su s kr i st al liz at or da suv y o r d a m i d a sovitilib
kristallga ayl antiriladi. Yirik kristallar olish u c h u n e r i t m a sekin sovi-
tilishi kerak. Kristall hosil b o ‘lishi u c h u n e r i t m a g a q u v u r l a r t us hur i b
q o ‘yiladi, s o ‘ngra krist allar ajratilib o l i n ib t a y y o r
m a h s u l o t sifatida
j o ‘natiladi.
39 3