FOOD GRADE PHOSPHORIC ACID BY THERMAL PROCESS

Phosphoric acid is an important intermediate chemical product. It is used mainly by the fertilizer industry. In 1980 the worldwide production capacity for phosphoric acid yielded about 33 million tons of P2O5 equivalents.

Pure 100% phosphoric acid is a white crystalline solid (monoclinic) that melts at 38.85oC to a syrupy liquid which has a strong tendency to super cool.

In dilute solutions, phosphoric acid has a pleasingly sour taste which is similar to but distinguishable from that citric, tartaric, lactic and acetic acids Rock phosphate is the major and essential raw material required for production as phosphoric acid by any route. Usually, when considering a phosphate rock as a potential raw material, the first approach is to analyze its chemical composition, i.e. the P2O5 content and its impurities.

Phosphoric acid (H3PO4) is produced by 2 commercial methods: wet process and thermal process. Wet process phosphoric acid is used in fertilizer production. Thermal process phosphoric acid is of a much higher purity and is used in the manufacture of high grade chemicals, pharmaceuticals, detergents, food products, beverages, and other nonfertilizer products.

There are two basic methods in commercial use for the production of phosphoric acid – the wet process and the furnace process. In the electric furnace process elemental phosphorous is produced by the electrothermic reduction of phosphate rock with carbon (coke). The silica added to the furnace charge behaves as a strong acid at the high temperatures (about 1500°C) employed in furnace operations and combines with the calcium constituent of the phosphate rock to form calcium silicate. The overall reaction, neglecting carbonates, fluorides, and other non-phosphatic constituents, may be expressed as follows:

In the manufacture of furnace phosphoric acid, the condensed elemental phosphorus is burned in air. The phosphorus oxide vapor (P.01o) formed reacts with water to produce phosphoric acid.

The phosphoric acid thus produced has very small amounts of impurities and the major industrial markets for this acid are in the manufacture of sodium phosphates and tetra potassium pyrophosphate for use in detergents and calcium phosphates for use as an animal feed supplement and in dentifrices, medicinal, glass, food, and plaster stabilizers.

INTRODUCTION
PHOSPHORIC ACID FROM ROCK PHOSPHATE
PHOSPHORIC ACID (ORTHO) FOOD GRADE (75%)
PRODUCT SPECIFICATIONS
PROPERTIES & SPECIFICATION OF PHOSPHORIC ACID
PURE PHOSPHORIC ACID:-
TYPICAL ANALYSIS OF PHOSPHORIC ACID
PROPERTIES
PHOSPHORIC ACID POSSESSES FOLLOWING PROPERTIES:-
USES & APPLICATIONS
PHOSPHORIC ACID IS USED IN A NUMBER OF AREAS, FEW OF ITS
USES ARE GIVEN BELOW:-
GRADES OF PHOSPHORIC ACID
REQUIREMENTS FOR ORTHOPHOSPHORIC ACID
B.I.S. SPECIFICATION
MARKET SURVEY
ANNUAL PRODUCTION OF PHOSPHORIC ACID
DETAILED IMPORT DATA OF PHOSPHORIC ACID
85 FOOD GRADE
EXPORT DATA FOOD GRADE PHOSPHORIC ACID
PRESENT MANUFACTURERS/EXPORTERS/SUPPLIERS OF PHOSPHORIC ACID
TECHNOLOGY OVERVIEW OF PHOSPHORIC ACID
WET ACID PROCESS
THERMAL PROCESSES
ELECTRIC FURNACE PROCESS
THE HARD PROCESS
THE IMPROVED HARD PROCESS
IHP PROCESS DESCRIPTION
MANUFACTURING PROCESS OF PHOSPHORIC ACID (FOOD GRADE)
BY THERMAL PROCESS
RAW MATERIAL REQUIREMENTS
PROCESS FLOW DIAGRAM
PURIFICATION OF PHOSPHORIC ACIDE
PROCESS IN DETAILS
TABLE (METRIC AND ENGLISH UNITS). CONTROLLED EMISSION
FACTORS FOR THERMAL PHOSPHORIC ACID PRODUCTION
EMISSIONS AND CONTROLS
DIFFERENT PRODUCTION PROCESSES
OF PHOSPHORIC ACID
IN EUROPE THE MORE CURRENT PROCESSES ARE THE FOLLOWING:-
TABLE: SHOWS THE VARIATION IN CHEMICAL ANALYSIS
OF VARIOUS PHOSPHATE ROCKS.
PRINCIPLES OF THE PROCESS
DIHYDRATE PROCESS
THE DISADVANTAGES ARE:-
DIHYDRATE PROCESS.
GRINDING
REACTION
FILTRATION
CONCENTRATION
HEMIHYDRATE (HH) PROCESS
CAPITAL SAVINGS.
PURER ACID.
LOWER ROCK GRINDING REQUIREMENTS.
FILTRATION RATE.
PHOSPHATE LOSSES.
SCALING.
FILTER CAKE IMPURITY.
CORROSION.
RECRYSTALLISATION PROCESSES
SEVERAL PROCESSES HAVE BEEN DEVELOPED BUT THERE ARE
ONLY THREE BASIC ROUTES:-
PURIFICATION OF GREEN PHOSPHORIC ACID
TO FOOD GRADE PHOSPHORIC ACID
STORAGE AND HANDLING OF PHOSPHORIC ACID
STORAGE CONSIDERATIONS
CONSTRUCTION MATERIALS
STORAGE TANK
• STAINLESS STEEL
• RUBBER-LINED CARBON STEEL
• FIBERGLASS REINFORCED POLYESTER (FRP)
HEALTH AND SAFETY INFORMATION
FIRE, EXPLOSION AND HEALTH HAZARD DATA
TOXICOLOGICAL INFORMATION
PERSONAL PROTECTIVE EQUIPMENT
TECHNOLOGY SUPPLIERS FOR PHOSPHORIC ACID
SUPPLIERS OF RAW MATERIALS
PHOSPHATE ROCK
SILICA SAND
LABORATORY CHEMICALS
SODIUM HYDRAUXIDE
CALCIUM HYDROXIDE
SULPHURIC ACID
PACKAGING MATERIALS (HDPE WOVEN LAMINATED BAGS)
SUPPLIERS OF PLANT AND MACHINERY
JAW CRUSHER
ELECTRIC ARC FURNACE
EVAPORATORS
FLUIDIZED BED DRYER
AIR COMPRESSORS
LABORATORY EQUIPMENTS
PACKAGING MACHINE
INSTRUMENTATION & PROCESS CONTROL EQUIPMENTS
MATERIAL HANDLING EQUIPMENTS
STORAGE VESSEL
D.G. SETS

APPENDIX – A:

1.      COST OF PLANT ECONOMICS
2.      LAND & BUILDING
3.      PLANT AND MACHINERY
4.      FIXED CAPITAL INVESTMENT
5.      RAW MATERIAL
6.      SALARY AND WAGES
7.      UTILITIES AND OVERHEADS
8.      TOTAL WORKING CAPITAL
9.      COST OF PRODUCTION
10.      PROFITABILITY ANALYSIS
11.      BREAK EVEN POINT
12.      RESOURCES OF FINANCE
13.      INTEREST CHART
14.      DEPRECIATION CHART
15.      CASH FLOW STATEMENT
16.      PROJECTED BALANCE SHEET