Optimization and Avoidance of Pain Points in Sulphoaluminate Cement Production by Rotary Kiln with Phosphogypsum

In view of a series of production difficulties such as fluctuation of phosphogypsum impurities, easy loss of sulfur components, difficult control of kiln conditions, unstable finished products, ring formation and blockage, the industry can adopt the closed-loop idea of "pre-treatment + steady-state control kiln + formula bottom-up + system homogenization" to solve the problem from the root, rather than back-end. The specific scheme is as follows:

1. Avoid from the root: standardization of phosphogypsum raw material pretreatment (to solve the core problems of impurity fluctuation, excessive phosphorus and fluorine, and unstable moisture content)

. 90% of all process problems in the kiln are due to substandard raw materials, and priority should be given to pre-treatment. Completely avoid congenital defects:

1.2.3

.

II. Optimization of calcination process: precise control of kiln with narrow temperature window (to solve the problems of difficult temperature control, sulfur loss and unqualified mineral phase)

. The calcination window of sulphoaluminate cement is extremely narrow. Core optimization logic: reduce the high temperature peak value, shorten the high temperature residence, stabilize the sulfur and protect the mineral phase

1.2. Optimize the ratio of air and coal in the kiln, reduce the primary air speed, control the reasonable excess air coefficient, use the micro-reduction atmosphere to calcine, greatly reduce the volatile escape of SOSO, and stabilize the ratio of sulfur and aluminum in the system. And ensure that that calcium sulphoaluminate serving as a core mineral is sufficiently generate. 3. that bottom of the

formula system: adapt to the characteristics of the phosphogypsum (fault-tolerant production and stable finis product quality)

; the formula of the natural gypsum is not suitable for the phosphogypsum, Exclusive formula optimization can greatly improve the production fault tolerance rate:

1.2.3

.

IV. Equipment and working condition optimization: completely solve the problems of ring formation, material blockage, Problems

of poor continuity 1.2.3 V. Stability control at the back end of

finished products: problems

of avoiding stability and strength fluctuation 1.

2.6. Core summary: Optimal avoidance logic (simplest landing logic)

1. Do not rely on kiln "parameter adjustment remedy", all pre-treatment: raw material stability is the premise of all process stability, solve the problem of raw materials, can avoid 80% of production failures; 2.

VII. High-quality stabilized sulphoaluminate cement clinker: core characteristics, strength levels, Applicable Scenarios and Alternative Boundaries

(I) Core Inherent Features (Different from Ordinary Portland Clinker)

1.2.3.4.5

.

(II)

High quality sulphoaluminate cement clinker, with clear standardized strength range for mass production and stable performance:

1.1-day compressive strength: 30 – 40MPa (more than 70% of the 28-day strength of ordinary cement; Realize the same day construction, the same day traffic, the same day stress);

2.3 days compressive strength: 45 – 55MPa;

3.

(III) Core applicable scenarios (areas that cannot be replaced by rigid demand)

1. Emergency repair works: rapid repair of roads, bridges, tunnels, airports and factory buildings, municipal emergency construction, shortening the shutdown cycle;

2. Low temperature construction project in winter: civil construction in northern winter and alpine regions, without antifreeze, without thermal insulation and maintenance, to solve the pain point that ordinary cement can not be constructed in winter;

3. Impervious, waterproof, plugging works: basements, tunnel roofs, pools, water conservancy projects, subway segments, relying on micro-expansion characteristics to achieve self-waterproofing, to eliminate leakage and cracking;

4. Corrosion-resistant special engineering: coastal marine engineering, saline-alkali land infrastructure, chemical plant floor, sewage treatment structures, to resist acid and alkali, sulfate, seawater erosion;

5. Prefabricated components and prefabricated buildings: prefabricated wallboards, pipe piles and culvert components can be demoulded quickly, which can greatly improve the turnover efficiency of moulds, reduce costs and increase efficiency;

6.

?

2. The core reason is that the hydration heat release of sulphoaluminate cement is concentrated, the late toughness is weak in adapting to conventional civil working conditions, and the material premium is higher than that of ordinary cement, the pure substitution cost performance is low, and the adaptability is redundant.

3.

(V) Summary

of the core value of the industry Phosphogypsum-based sulphoaluminate clinker with stable mass production is not a low-end substitute for ordinary cement, but a high-value clinker with high-end special and low-carbon solid waste recycling. In the era of stock subtraction economy, it avoids the Red Sea roll of ordinary Portland cement, focuses on special rigid demand, low-carbon resource utilization and substitution of harsh working conditions, and has higher product premium, stronger policy advantages and more scarce market competitiveness.