Cau 3:

m=1 kg; V1= 520ml; V2= 910ml

ρc= 2,6 g/cm3; ρn= 1 g/cm3

W=?

Bai giai:

The tich nuoc dang len khi cho cat vao binh:

∆V= 910- 520= 390 (ml)

Khoi luong cat kho

mk= mw/ (1+W)

The tich dac cua cat

Vac= mk/ρc= mw/ (1+W).ρc

The tich cua nuoc trong cat am

Vn= mn/ρn= mw.W/ [ρn.(1+W)]

Vac+ Vn= ∆V= mw/ [(1+W). ρc]+ mw/ [ρn.(1+W)]= 390 cm3

→ W= (∆V.ρc - mw)/ [ρc.(mw- ∆V.ρn)] .100%= (390. 2,6- 1000)/ [2,6. (1000- 390.1)] .100%

        = 0,88%

Cau 1: Do lon cua cat co anh huong toi tinh deo va cuong do cua be tong nang nhu the nao? Hay neu cac chi tieu danh gia do lon cua cat?

- Cat dung de che tao be tong co the la cat thien nhien hay cat nhan tao.

Cat la 1 loai da, la san pham cua qua trinh vun nat cua cac da co truoc la san pham cua qua trinh san xuat. No co do lon 0,14 ÷ 5mm.

Chat luong cua cat phu thuoc vao 3 yeu to:

+ Thanh phan khoang, thanh phan hat va ham luong tap chat.

+ Luong ngam tap chat gom cac hat set, tap chat muoi huu co, cac loai muoi la cac thanh phan co hai, lam anh huong toi chat luong be tong nen cung phai thoa man nhung yeu cau qui pham.

+ Thanh phan hat va do lon cua cat:

d1/d2= d2/d3= d3/d4=… dn/dn+1= 2

Day la cap phoi lien tuc, de thi cong nhung luong dung XM chua tien toi do min, cuong do xi mang chua den maximum. Nha nuoc su dung cap phoi nay lam cap phoi tieu chuan.

Neu cap phoi 6 ÷ 10 goi la cap phoi gian doan, kho’ thi cong nhung luong dung ximang it va cho cuong do cao.

- Do lon cua cat co anh huong den luong dung XM va duoc bieu thi bang modun do lon, ty dien tich va luong nuoc yeu cau. Modun do lon Mdl duoc xac dinh bang CT:

Mdl= (A2,5+ A1,25+ A0,63+ A0,315+ A0,14)/ 100

- Dua vao cac hi tieu ve do lon nguoi ta phan cat ra cac loai nhu sau:

Mdl

Sy (cm2/g)

Nyc (%)

Lon

Trung binh

Nho

Rat nho

>2,5

2 – 2,5

1,5 – 2

1 – 1,5

-

-

100 – 200

201 - 300

<7

7 – 7,5

> 7,5

-

Cau 2: Nguyen lieu va qua trinh san xuat voi ran trong khong khi? Cac bien phap nang cao chat luong voi trong qua trinh nung?

1/ - Nguyen lieu: la cac loai da giau khoang CaCO3 co ham luong CaCO3 ≥92% va tap chat ≤8% co lan MgCO3 ≤ bao gom cac loai da: da voi, da phan, da voi dolomite, da dolomit

    - Qua trinh san xuat:

+ Chuan bi nguyen lieu: nguyen lieu duoc khai thac tu mo? dua ve lo' sau do gia cong de loai bo tap chat, dap nho co’ kich thuoc 8-20cm; sau do duoc xep vao lo' to duoi nho? tren, lo nung dat hieu qua va hoat dong lieu tuc

+ Nung:

Xay ra phan uc CaCO3 ↔ (900-1100°C) CaO+ CO2↑ +42,5Kcal/kg

ngoai ra con co MgO do su phan giai MgCO3.

Dac trung cho phan ung la he so Kp: Kp= PCaO.PCO2/ PCaCO3

Kp<1 xay ra phan ung nghich

2/ Nhan xet ve qua trinh nung voi va san pham cua chung

+ Phan ung nung voi la phan ung thuan nghich

+ Day la phan ung be mat do vay kich thuoc cua vien da phai phu hop thi phan ung moi triet de

+ La phan ung phu thuoc vao nhiet do nung

+ t°<1100°C CaO+ SiO2 → CxSy bao phu vien CaCO3 phan huy chua het tao thanh nhung hat non lua

+ Cac hat gi'a lua va non lua goi chung la hat suo.ng lam ho^' voi kem deo

+ Cac san pham sau khi nung voi: CaO, hat gia lua, hat non lua MgO, tap chat

3/ Bien phap nang cao chat luong voi trong qua trinh nung

- Dam bao nhiet do lon hon 900°C → CaO + CO2↑ +42,5 Kcal/kg. Theo ly thuyet o nhiet do bang 900°C phan ung da xay ran hung khi nung va giai phong ra CO2 mat di 440%kl →trong voi de lai nhieu lo rong →he so truyen nhiet giam xuong →trong loi vien da nhiet do nho hon 900°C →phai nang cao nhiet do toi 1000°C de CaCO3 phan giai hoan toan

- Lo phai thong thoang de CO2↑ tang toc do de phan ung xay ra theo chieu thuan

- Nguyen VL kich thuoc cua vien da phai phu hop voi cong nghiep nung: lo gian doan, nguyen VL phai dong thanh banh xep xen ke. Da voi co the co kich thuoc nho nhung phai mo?ng. lo lien tuc thuong phai cho lan than vao trong da voi →da phai nho.