One of the basic activities of a refinery is desulfurization which involves removal of sulfur compounds largely H2S but probably also alkylthiols (R-S-H). In some countries,these compounds are oxidized into SO2 gas, and the latter is converted into SO3 which is transformed into sulfuric acid.The method of choice to get a fertilizer is to react  the acid with ammonia: 2 NH3 + H2SO4 ----> (NH4)2SO4 .  Ammonium sulfate is relatively cheap fertilizer & it provides the soil with the essential element (nitrogen) plus the additional important element (sulfur). It is also, as you rightly said, useful for alkaline soil because ammonium sulfate is an acidic salt "it came from strong acid & a weak base".

Refinery ( petroleum) S is largely created as molten elemental sulfur by reacting H2S and air at steam heat to get intermediate SO2 and H2S reacting to S and H2O.  It is usually transported molten away from the refinery in special train cars. For fertilizer it is prilled by cooling molten sulfur in spray towers, and this is effective for slow release incorporation in soils. Highly alkaline soils may not have the requisite populations of S oxidizing bacteria, so ammonium thiosulfate is preferred. This generates H+ from both the N and S oxidations and the requisite bacteria are usually present in these soils.

Where there is an anhydrous NH3 factory near a petroleum refinery, the reactions of the H2S and air can be scrubbed into NH3 to make solutions of ammonium thiosulfate.

The organic S component described in S cycles is not related to the petrochemical S, as it is microbially bound ( labile upon death of microbe) and bound by sulfate bonds to phenolic components in humin( recalcitrant) as well as chemisorbed Fe in humic networks.  Only the reduced S species will be useful for H+ during oxidative mineralization, and mellow alkaline soils. Better approach as I pointed to in earlier answer is ammonium thiosulfate, not organic, but effective.

In my opinion from an industrial point of view, it will be best to oxidise S by burning it an incinerator and to absorb the SO2 gas in an alkaline scrubber such as ammonia solution/lime water to produce either ammonium sulphate  or calcium sulphate, these can thus be used as Sulfate source for the alkaline soil

My Dear Matar, Nelson and Paul

I sincerely thank you for guiding me. I will run a batch with ammonium thiosulfate first and let you know the results.

Thank you all again.

Truly yours

karbassi

The difference with using ammonium thiosulfate or dithionate is the production of extra H+ through the oxidation of the reduced S bound in the molecule. What you have described industrially produces a sulfite solution, unless the SO2 is further oxidized  to form SO3 and consequently sulfates, the fuming sulfuric acid processes. In the town I lived in Texas our petroleum refinery made liquid sulfur internally through the partial oxidation of  H2S in a large underground reactor, the process described above. At other factories across town was a large carbon black plant making carbon and H2 from natural gas or gasoil( two very differently configured reactors depending on feedstock). The H2 was piped to a third factory nearby that made Haber Process anhydrous ammonia. A fourth factory used some of this ammonium stream and an H2S stream and oxidation with SO2 intermediate to make ammonium thiosulfate. It involved a scrubbing process so the hot solution could be cooled and crystallized for high purity sales, with some mother liquors being made into liquid fertilizers.  

There is nothing wrong usually to use ammonium or calcium sulfates for acidizing soils since they can have an immediate effect of neutralizing alkaline carbonates and some residual acidizing through amphoteric ion exchange. Ammoniun in principle will oxidize to nitrate and give additional H+, but will require active carbon residue microbial oxidation to accomplish this mineralization.  On highly alkaline soils it is not unheard of to use the H2SO4 directly, since it has immediate neutralizing capability, and is the source chemical for the sulfate fertilizers.

Dear Nelson

Thank you again for your very descriptive discussion. I got the point. In Iran, granular S is being produced in refineries (Something around 10 million tons of S per year). I will try out the method discussed by you and let you know about the results. I am now sure that we will produce sulfate fertilizers very effectively.

karbassi 

Why don't you mix the sulphur source with organic materials (with a cooling period of 15-20 days) to get the desired sulphate compost? It may be called as sulpho compost! Some people produce sulpho nitro compost too.

Dear Ramesh

Thank you for your suggestion. The amount of granular S is about 10 million tons and therefore we have to have enough organic material (for instance compost) and ample space to mix them up.

Truly yours

Don't forget need for water and air. It is often lack of water that is responsible for ClORPT genesis of alkaline soil profiles in dry climes like Iran and southwestern USA  Composting is accomplished best by adhering to Leibigs' law of minimums, and Redfield Ratios for microbial immobilization.

Dear Karbassi,

I understand. This may be given as a masters thesis work to any student to find out the best possible way to utilize the organic waste, for eg even weed biomass (available at cheap cost) in your country (instead of relying on  animal manures, which is commonly used as compost manure in many countries) for sulpho compost. You can share the results with us in future.

Dear Ramesh

Yes, I will post out the results of experiments to you and other people who helped me in this way.

Truly yours

Dear Dr. Nelson

Thank you very much for your fruitful suggestions. We have started the laboratory works and once we come up with good results; we surely take care of Redfield ratios for microbial immobilization.

Truly yours

Dear Karbassi

Conversion of organic S into sulphate-S will be mediated by biotic or abiotic processes. I am assuming you are interested in converting organic S into plant available S when you apply such material onto soil.  Mineralisation of organic S will be the best possible pathway for this. You will have to look at the C:S ratio and ways to improve enzymatic activities e.g arylsulphatase.

Regards

Anwar Ghani

Dear Ghani

Thank you for your guidance.

Truly yours

karbassi

Dear Anwar

Please send me some information on the methods of converting organic S into plant available S. What is the optimum C:S ratio?

I see the conversation is drifting away from the S speciation, in your last question. The microbial path of inorganic S ( elemental granules) is to be oxidised to inorganic SO4=; this is pathway for energy transfer to the microbe to assimilate and grow from organics in appropriate C,N, & P ratios. Air,and moisture and a sink for the protons( acid) generated by this process will keep it going. Some S will be incorporated into the microbes as organic essential cellular components but most will be immediately plant available, subject to inorganic precipitation reactions, or leached to lower levels of soil where redox reactions can revert it to sulfide ( this is also microbially mediated ). 

I think moisture will be your limiting nutrient, and limiting reagent of change. Alkaline soils will also have issues with P availabilty since Ca and OH  will limit its solubility, but this will change as acid is generated from organic C to CO2,and S to SO4= ,microbially mediated during composting.

Dear Nelson

Thank you very much for the fruitful discussion of past 45 days. Now, we have produced Ammonium Thiosulphate (liquid). We are getting the test of quality. It is almost 98% pure and we are waiting for the other tests such as C and N contents. Since the final product is liquid that will be mixed by agricultural water, ample moisture content might be gained. I will send you the tests results very soon.

Truly yours

karbassi

Thank you... please check with some engineers for corrosion/ material handling  of liquid especially if it to be applied with center pivot; I seem to recall that it mildly corrosive and can swell some elastomers used for seals; this will be lesser since it is dosed at dilution, and I think passivated Aluminum piping is fine. 

Dear Nelson

The usual practice in Iran include pumping water into a pool. The pool is having many outlets that ends up to the natural channels. Thus, nothing is on the way to be corroded. In some parts, we used PVC pipes. 

I thank you once again.

karbassi