The manufacture of phosphoric acid from phosphate rock by wet process has been studied. The pilot plant consists of two systems, digestion system(I) and filtration system (II) . In(I),five reaction tanks are arranged in series. The ground phosphate rock is fed into the first tank. Sulfuric acid mixed with weak phosphoric acid returned from (II) is fed into the second one. The digested slurry from the last tank is pumped to a vacuum flash cooler, where most of heat is removed. The cooled slurry flows back into the first tank with a circulating ratio of 13~15:1. In (II), a continuous horizontal tilting-pan type filter is used, which comprises 15 seperate filter pans having a total filtering area of 1.5 square meters. The pans can be filled automatically. The filter cake, which is subjected to two counter-current washes, can be unloaded by automatically overturning the pans. The recovery of soluble P2O5 from filtration is >99% . The maximum capacity of the filter is 800 kg. dry cake/M2-hr.. The acid produced (from the first filtrate) is 30~32%P2O5.

This is to introduce a process for making diammonium phosphate fertilizer of 18-46 in which the raw materials used are dilute wet-process phosphoric acid and ammonia. The authors have studied the degree of neutralization of phosphoric acid with ammonia in relation to the ratio between N and P2O5 in product, the ratio between the liquid and solid phases in paste, the amount of water and ammonia evaporated from paste, etc.. At the same time, the authors have also studied the pelletizing and drying of the product, the recovery of dust from the tail gas, as well as the construction of various equipments. From their studies, they have found the following results. I. The optimum conditions for making diammonium phosphate fertilizer of 18-46 grade are as follows. a. The optimum concentration of phosphoric acid is 32% P2O5, b. the proper degree of neutralization of phosphoric acid with ammonia is at 1.78, and c. in pelletization, the recycling material which is 40% -6 to +12 mesh, 60% -12 mesh, and the quantity ratio is about 11 times of the product. II. They have also determined the construction and the materials for making the reactor, the pelletizer of horizontal type with double axis, the rotary dryer, and the scrubber of impingement type, etc..

The relation between the oxygen absorption and the composition of oxidized wax in the course of liquid-phase deep oxidation of paraffin wax has been studied. The experimental results show that the oxidized wax is almost composed of acids with different functional groups, of which carboxyl group predominates, ester group is the next (about one half the quantity of carboxyl), then comes the carbonyl group, but the hydroxyl group is almost zero. When the acid value of oxidized wax amounts to about 250mg.KOH/g., an appreciable amount of C4-C10 dibasic acids commencos to be produced, and their yield will be rapidly increased as the oxidation proceeds more deeply. With a suitable catalyst and better contact between the gas and the liquid, the rate and selectivity of the deep oxidation reaction of paraffin wax are dependent on the reaction temperature and the partial pressure of oxygen used, so that the oxidation should be carried out as much as possible under chemical kinetic conditions to reduce the effect of diffusion. Furthermore, the experimental results show that the ratio between the ester value and acid value may be considered as an index to show whether the diffusion rate of oxygen meets the requirements of the kinetic velocity of oxidation or not. This ratio may also be used to estimate the maximum acid value that oxidation can produce. The variation of the product yields in the oxidation reaction indicates the rapid decrease of oxidized wax in the final reaction stage due to the very high velocity of formation of CO2 and condensed water phase. When acid value exceeds 400, the yield of C4-C10 dibasic acids up to 40% will result. By chromatographic analysis, it is found that the yield of succinic acid in general is the highest, glutaric acid the next and that of C4-C5 and C6-C10 dibasic acids in about equal quantities.

The present work deals with preparation of two groups of compounds represented by the general formulae: where R represents one of the following aliphatic groups. and Ar, one ot the lollowing aromatic groups. These compounds have been prepared by dehydrating tributyltin oxide with an organic acid, or by the condensation of tributyltin chloride with an organic sodium salt. It has been found that the reaction proceeded smoothly with yield up to 90% . Some physical constants of these compounds have been also determined. The preliminary biological screening test shows that compounds OTQ02, OT003 and OTQ07 exhibited remarkably high fungicidal effects on hypochnus sasakii shirai.

In the present work, several tri-butyl~(alkylthio) tin type compounds have been prepared from bis-(tributyltin) oxide and mercaptan. Preliminary biological screening tests show that compound OT029 exhibits re~ markably high fungicidal effects on hypochnus sasakii shirai. It has been found that the enhanced fungicidal effects may be attributed to the introduction of ethylenic linkage into the structure of this compound.

In the present paper, as a second part of the previous paper published in this journal (No.1, 16-23, 1958), the authors made further experimental studies on single slots of different shapes and dimensions to correlate slot opening with air flow rate. Considering the vapor velocity in the annular space between the riser and the bubble cap in operation, which had been neglected in the single slot studies, the authors presented a new approach to evaluate the slot opening, which was tested experimentally. (1) For single slot studies, experimental conditions were extended as follows. Slot dimensions, rectangular slots, 6=2.27-25.28mm; triangular slots, B/H=0.255-1.40; trapezoidal slots, (B2-B1)/H=0.072 -0.796. Air flow rates. Vs≤357×102litres/hr. Immersed depth. 30mm. The results shows that the value of the discharge coefficient u in the Rogers-Thiele formula is not a constant but a function of Reynolds number as well as slot dimensions. For definite slot dimensions, the value of u will be a constant only when the air flow Reynolds number is high. ( 2 ) With the effects of the annular space vapor velocity considered, the authors proposed the following formulas as a modification of those of Rogers and Thiele. Rectangular slots. Triangular slots. Trapezoidal slots. It is apparent that the Rogers-Thiele formulas are only special forms of the above with a= 0.( 3 ) Formula (6) was tested experimentally in a single bubble cap, with the following experimental conditions. Bubble cap shape and dimensions. Circular cap with 40 rectangular slots; Cap I.D., 100mm; Riser O.D., 68mm; Slot width, 4mm; Slot height, 25mm. System. Air-water. Operating conditions. Static immersed depth, 15mm; Air flow rates,V = 22.1-111.0 cubic metres/hr. The results point out that the formulas proposed in the previous paper can be applied to bubble caps at Re≥2600 without appreciable error. The experimental data were compared with the calculated values of slot opening from the Rogers-Thiele formula, the Cross-Ryder formula, the formulas in the previous paper,and formula (6 ) in this paper. It has been found that when Re≥2000, the maximum deviation for formula (6 ) was 3%, while that for the other formulas were 17.5%, 9.2% and 8.5% respectively. After making a theoretical analysis, the authors are of the opinion that the formulas proposed can represent to a certain extent the operating conditions of a bubble cap. Similar results could be anticipated from a bubble cap with triangular or trapezoidal slots, but further experimental studies will be needed.