I. Background Technology
At present, Chinese boric acid two-step production processes mainly include borax nitric acid method and borax sulfuric acid method. As far as the above two processes, the technological process must extract by-product sodium nitrate or sodium sulfate, otherwise the production will not be able to continue. The existing extraction method is to conduct evaporation and concentration for boric acid mother liquid, then produce sodium nitrate through cooling, or separate sodium sulfate by crystallization under evaporation condition. Because evaporation is required for boric acid mother liquid, it increased equipment investment, consumed relatively high energy in evaporation process, substantially increased operating cost, and finally influenced economic benefits of the production enterprise. In order to reduce energy consumption and effectively control production cost of boric acid and by-product extraction process, after successfully developing new process of evaporation-free preparation of boric acid and sodium sulfate, Nanyang Pengmei Industrial Technology Research Institute innovated and developed Chinese existing borax nitric acid process, and successfully developed new process taking nitric acid as neutralizing agent to dispose industrial borax or borax ore, and preparing high quality industrial boric acid and sodium nitrate without evaporating boric acid mother liquid, and industrialization has been smoothly accomplished.
II. Features of this Process
1. Applicable raw materials:
Decahydrate industrial borax, industrial pentahydrate borax, borax ore and nitric acid.
2. Process gist:
On the premise of totally closed cycle of boric acid mother liquid, reasonably control reaction concentration and other relevant process conditions, enable borax or borax ore to react with nitric acid and generate boric acid and sodium nitrate. Then produce boric acid and sodium nitrate through filtration, cooling, boron sodium separation, dehydrating, washing and drying. Boric acid mother liquid generated during separation is recycled in dissolving the mixed material. The technological process does not need to evaporate boric acid mother liquid.
3. Advantages of this process:
(1) Save equipment investment by 15%;
(2) Reduce coal consumption 67%, and save electricity 10% (calculated according to production of 1t boric acid);
(3) Product quality: boric acid is in conformity with GB/t538-2006 premium grade product standard, and sodium nitrate is in conformity with relevant national standard;
4. Evaluation of boric acid production cost: (calculated according to production of 1t boric acid)
(1) Take borax pentahydrate as raw material:
Borax pentahydrate, 1200kg, unit price 4.5 Yuan/kg, and sum 5,400 Yuan;
Nitric acid (50%), 1100kg, unit price 0.8 Yuan/kg, and sum 880 Yuan;
Coal, 150kg, unit price 0.9 Yuan/kg, and sum135 Yuan;
Electricity, 100kw.h, unit price 0.7 Yuan, and sum70 Yuan;
Packaging material, 75 Yuan;
Salary, 250 Yuan;
Other items, 20 Yuan;
Total: 6,830 Yuan.
(2) Take borax ore as raw material(grade 27%):
Borax ore, 2350kg, unit price 1.5 Yuan/kg, and sum 3,525 Yuan;
Nitric acid (50%), 1,100kg, unit price 0.8 Yuan/kg, and sum 880 Yuan;
Coal, 300kg, unit price 0.9 Yuan/kg, and sum 270 Yuan;
Electricity, 120kw.h, unit price 0.7 Yuan, and sum 84 Yuan;
Packaging material, 75 Yuan;
Salary, 250 Yuan;
Other items, 50 Yuan;
Total: 5134 Yuan.
(3) Output:
Boric acid 1000kg, unit price 5.9 Yuan, and sum 5,900 Yuan;
Sodium nitrate580kg, unit price 2.1 Yuan, and sum 1,218 Yuan.
Total: 7,118 Yuan
(4) Profit of product/t:
Borax method: 288 Yuan/t;
Borax ore method: 1,984 Yuan/t.
III. Technical Form of Cooperation:
Technical transfer. Taking responsibility for process flow design, supporting equipment of standard equipment, non-standard equipment manufacture design, equipment is plane layout design, equipment installation design, pipe network design, equipment installation guidance, equipment commissioning, production commissioning, training for production engineers, analysis staff and technicians, process operation specifications, raw material and product analysis method, and preparation of intermediate control analysis method; ensuring output, yield and quality to reach the standard; and undertaking turn-key projects.