CN201809170U - Production equipment of phosphoric acid adopting reflection kiln method - Google Patents

Abstract

The utility model belongs to the technical field of inorganic salt industry, and relates to a new technique which adopts medium-low grade phosphate ore and yellow phosphorus as raw materials and adopts a reduction and oxidation method for preparing phosphoric acid directly. The technique is as follows: a dry chain grate machine is used for adding reaction material (namely, compound pellets) quantitatively to a reflection kiln, the yellow phosphorus is adopted to replace coal for burning and heating, the heat is transferred to the compound pellets by a reflecting mode, reduction reaction occurs on the compound pellets, P4 precipitates the compound pellets and is oxidized into P2O5 kiln gas which is introduced into a hydration tower, and high-purity phosphoric acid is obtained by procedures of purifying and the like. The method uses the yellow phosphorus to replace the coal for burning, heating the reacting pellets to provide heat for reducing P4 steam from phosphorite, furthest realizes comprehensive utilization of the heat generated by burning the yellow phosphorus, saves the energy, and greatly reduces the cost; no looping exists in the kiln, the reaction rate is high, the equipment structure is simple, the volume is smaller and the operation and the maintenance are convenient.

Description

A reverberatory kiln production equipment for phosphoric acid

technical field

The utility model belongs to the technical field of phosphoric acid production in the inorganic salt industry, and relates to a process technology for preparing phosphoric acid by using medium and low-grade phosphate rocks as raw materials and adopting a reduction-oxidation method. the

Background technique

The situation of energy shortage in our country is quite severe, and saving energy has become an urgent task we are facing. Among them, after decades of mining of phosphate rock resources, there are very few high-grade ores, and there are very few ores that can be directly used in the production of wet-process phosphoric acid in China; It is very difficult to mine and utilize high-grade phosphate rock, especially for the phosphoric acid industry. the

Therefore, in the 1980s, the Western Petroleum Research Corporation of the United States developed a new process for preparing industrial phosphoric acid - kiln phosphoric acid, but this research has not been industrialized due to the problems of reaction engineering technology. On the basis of foreign research, domestic technicians have developed many new kiln phosphoric acid production methods:

1. Rotary kiln: This is a heavy-duty, high-torque, multi-fulcrum, cylindrical hollow kiln operating system. The spherical material moves in the kiln with the rotation of the kiln body; the reduction of phosphorus is carried out in the reduction zone, P ₄ The oxidation of the furnace is carried out in the oxidation zone, the reduction zone and the oxidation zone are both in the kiln body, and the fuel is burned in the kiln for direct heating. This technology has many deficiencies: the separation of the oxidation zone and the reduction zone is not considered, and the reduced carbon in the material is easily oxidized and prematurely occurs, so the amount of carbon used is large, and the reduction of phosphorus is affected at the same time; in addition, ring formation in the rotary kiln The phenomenon is serious, which affects the normal operation of the kiln and is difficult to realize industrialized production.

2. Tunnel kiln: This is a long linear tunnel with fixed walls and arched (flat) roofs on both sides and the top. The kiln car is running on the track laid at the bottom, and the combustion equipment is located on both sides of the middle of the tunnel kiln. ;Using smoke insulation or open flame firing materials are placed on the kiln car, passing through the preheating zone, high temperature zone and cooling zone; although this technology solves the problems of tumbling, crushing and ring formation of materials in the kiln, there are still oxidation zones The problem of effective isolation from the reduction area, but also the problems of bulky equipment, low degree of mechanization, complex production process, long reduction reaction time, low reduction rate, and difficulty in realizing large-scale industrial production. the

3. Kundao kiln: This is an improvement of tunnel kiln technology. Compared with tunnel kiln, although the reaction time of phosphate rock is shortened and the degree of automation is improved, there are still problems of large volume and complicated production process. the

4. Ring-bottom kiln: Ring-bottom kiln has complex structure and cumbersome operation, and it is prone to gambling under high temperature. the

5. The patent No. ZL200920081113.3 provides a vertical kiln method. Although this kiln method has a simple structure, can effectively isolate the oxidation zone and the reduction zone, does not form rings in the kiln, and uses heat more reasonably, but due to The equipment is vertical and relatively high (20 meters), so it is easy to break the molding raw materials, and the reaction rate and resource utilization rate are thus reduced. the

The above methods all use coal to burn and release heat, and there is no combustion and release of heat that can make more use of phosphorus. the

Contents of the invention

Aiming at the deficiencies of the prior art, the utility model proposes a reverberatory kiln production equipment for phosphoric acid. The production of phosphoric acid by using this new phosphoric acid production equipment uses yellow phosphorus instead of part of the coal combustion, saves energy, and realizes energy in the production of phosphoric acid to the greatest extent. The comprehensive utilization of them greatly reduces the production cost. The equipment has a high reaction rate, no ring formation in the kiln, simple structure, small volume, low investment and convenient operation. the

The utility model provides a reverberatory kiln production equipment for phosphoric acid. The main structure of the reverberatory kiln _includes 1. furnace door; 2. feeding port; 3. _P2O5 outlet; 4. slag discharge port; 5. yellow phosphorus inlet ; 6. Air inlet. The kiln wall is lined with magnesia bricks; the kiln roof is arched and lined with silica bricks; the bottom of the kiln is sintered with magnesia-iron sand. The working principle is that the yellow phosphorus enters the reverberatory kiln for combustion through the yellow phosphorus inlet 5, and the heat is reflected to the compound pellets through the kiln roof, the kiln wall and the _hot gas _. Precipitation in the grains, and oxidation reaction occurs in the kiln to generate P ₂ O ₅ , and then introduced into the hydration tower through the induced draft fan; the heat generated by the oxidation reaction is also reflected to the composite pellets through the kiln roof, kiln wall and hot air; the composite residual pellets After the reaction, the volume becomes smaller and is discharged from the slag outlet 4.

The utility model provides a reverberatory kiln production equipment for phosphoric acid, and its new production process is as follows:

The phosphate rock, silica, and coke are measured according to the requirements, then crushed and ground into a fine powder of 200 mesh, then added with a binder, moistened and compacted, and then formed into balls with a disc pelletizer (diameter approx. 15mm). At the same time, the wrapping agent (coal and melting point regulator) is ball-milled, then added with a binder, then moistened and compacted, and wrapped on the surface of the above-mentioned pellets by another disc granulator to make composite pellets. Composite pellets are fed into the chain grate machine to use the hot air obtained from cooling residual balls for drying and preheating, and the hot balls enter the reverberatory kiln, where the pellets undergo reduction reaction and oxidation reaction takes place in the kiln. the

The reaction principle is as follows:

Inside the composite pellet:

Ca ₁₀ (PO ₄ ) ₆ F ₂ +15C+9SiO ₂ →3/2P ₄ +15CO+9CaO·SiO ₂ +CaF ₂ (1)

ΔH＝28006kJ/kg(P ₄ )

In the reflection kiln:

P ₄ +5O ₂ →2P ₂ O ₅ (2)

ΔH=-25498kJ/kg (P ₄ )

CO+1/2O ₂ →2CO ₂ (3)

ΔH=-22154kJ/kg (P ₄ )

In the above reactions, the heat released by reactions (2) and (3) largely meets the heat absorbed by reaction (1), so reaction (1) can continue. the

The reverberatory kiln generates kiln gas containing P ₂ O ₅ and introduces it into the hydration tower. After purification and other processes, high-purity phosphoric acid can be obtained. After the reaction, the residual balls enter the chain grate and blow air to cool, and the hot air is introduced into the drying chain and the reverberatory kiln for use.

The utility model adopts a reflective kiln production equipment for phosphoric acid. This production equipment combines the production principles of thermal phosphoric acid and kiln phosphoric acid. Its advantages are as follows:

1. In the reverberatory kiln described in the utility model, yellow phosphorus is used to replace part of the coal combustion, which saves energy, realizes the comprehensive utilization of energy in the production of phosphoric acid to the greatest extent, and greatly reduces the production cost. the

2. The utility model adopts yellow phosphorus combustion and heating composite pellets to replace the traditional coal combustion heating method, realizes comprehensive utilization of energy, saves cost, and ensures quality at the same time. the

3. In the reverberatory kiln described in the utility model, the heat is transmitted to the composite pellets through reflection, so the composite pellets are heated evenly and react completely, realizing full utilization of heat. the

4. The reverberatory kiln described in the utility model does not rotate, and there is no ring formation phenomenon. At the same time, because the distance between the feeding port and the kiln bottom is not high, there is no phenomenon of composite pellets being broken. the

5. The reverberatory kiln described in the utility model has simple structure, small volume, simple operation and convenient maintenance

Description of drawings

Fig. 1 is a structural schematic diagram of a reverberatory kiln of the utility model kiln process phosphoric acid production equipment

Figure 2 is a side view of Figure 1

Fig. 3 is a process flow diagram of the utility model

Detailed ways

Example 1

First, phosphate rock (28%), silica and coke are crushed and ground into a fine powder in a ratio of 10:7:3; take 200kg of fine powder, add a binder, moisten and compact, and then use a disc pelletizer Machine into composite pellets, about 15mm in diameter. Preheat with a grate and send it into the reverberatory kiln; 10kg of yellow phosphorus in the yellow phosphorus burner spontaneously ignites in the reverberatory kiln, making the temperature in the kiln gradually rise to about 1200°C; the reaction pellets undergo a reduction reaction at this temperature, And precipitate P ₄ steam, the reaction time is 1.5 hours; the reaction residual balls are discharged through the slag discharge port; the P ₄ steam oxidizes rapidly in the oxidation zone, and the kiln gas enters the hydration tower from the P ₂ O ₅ outlet, and then undergoes purification and other processes to obtain Obtain 120kg of high-purity phosphoric acid (85%), the yield of phosphorus reaches 95%, and the equipment runs stably in the reaction process.

Claims (2)

1. A reverberatory kiln production equipment for phosphoric acid, characterized in that the main structure of the reverberatory kiln comprises a kiln body and ancillary structures, the kiln wall of said kiln body adopts lined magnesia bricks, and the kiln roof adopts an arched top and an inner lining Silica bricks, the bottom of the kiln is sintered with magnesia iron sand; the auxiliary structure includes a furnace door, a feeding port, a P ₂ O ₅ flue gas outlet, multiple slag outlets, a yellow phosphorus inlet, and an air inlet. 2. The reverberatory kiln method production equipment according to claim 1, characterized in that the reverberatory kiln is connected with the hydration tower and the induced draft fan. the

Images