Urea briquette applicator for transplanted rice

A plunger-type, completely hand-operated applicator prototype, made of polyvinyl chloride (PVC), for deep placement of urea briquettes (UB), i.e., pillow-shaped urea supergranules with edges, in line transplanted rice has been developed for use by small-scale rice farmers. The field evaluation of the applicator was conducted in the Philippines during the 1989 dry season. The applicator consistently placed UB at proper depth (7 to 8 cm), which resulted in low concentrations of urea N (<7 ppm) in about 4 cm of floodwater 1 day after placement. These findings indicated that the prototype worked properly. Average work output of the applicator was 0.20 ha workday^–1 and may increase with practice. The yields of irrigated transplanted rice in the field trials show that agronomic efficiencies of hand-placed UB and applicator-placed UB were equal and were superior to those of split-applied prilled urea.     

煤与粘结剂的相互作用和型煤抗压强度的关系

煤的润湿性与型煤抗压强度相关。用于表征煤的润湿性方法有煤与淀粉粘结剂的接触角、粘合功、煤的润湿临界表面张力等。研究证明,随着煤化程度的升高,煤与淀粉粘结剂接触角变小,粘合功增加,粉煤的润湿性改善,型煤抗压强度得以提高。另外,煤的润湿临界表面张力越大,煤的润湿性越好,型煤抗压强度也就越高。     

纸浆黑液制气化型煤黏结剂研究

利用正交设计法研究纸浆黑液经化学改性制气化型煤黏结剂的工艺技术条件,结果表明:1 000mL纸浆黑液(固体质量分数45%)与80mL有机试剂A在80℃下恒温反应2h,然后升温至95℃,加入30mL有机试剂B,恒温反应1h;最后加入50g无机试剂M,充分搅拌0.5h,得到性能优良的纸浆黑液气化型煤黏结剂。用该黏结剂生产型煤,其抗压强度、落下强度、热稳定性分别为96kg/球、96%、95%,并具有良好的防水性能,完全达到了气化型煤的质量要求。     

Iron recovery from zinc mine tailings by magnetic separation followed by carbothermal reduction of self‐reducing briquettes

The volume of tailings produced by the extractive industry has been increasing due to the processing of the low‐grade ore. This issue can cause environmental accidents and require significant investment to control the disposal of tailings. Therefore, this study aims to recover iron from zinc mine tailings by wet magnetic separation followed by the carbothermal reduction of self‐reducing briquettes. Two magnetic separation routes were investigated to concentrate iron. Zinc mine tailings were processed by route I, in a rougher stage followed by a scavenger stage; and route II, in a rougher stage followed by a cleaner stage. The carbothermal reductions were performed using self‐reducing briquettes composed of Fe concentrate from the route with high Fe content and charcoal. The products were analyzed by scanning electron microscopy with energy dispersive spectroscopy (SEM‐EDS), x‐ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP‐OES), and volumetric chemical analysis. Magnetic separation route II provided the highest‐grade Fe concentrate, 52% Fe, while route I provided 33% Fe. In the carbothermal reductions, a metallization degree of 98% in the Fe concentrate briquette, 97% in the briquette with a 10% replacement of its raw material by Fe concentrate, and 99% in the hematite briquette was reached. The replacement of raw material by Fe concentrate showed no significant change in Fe recovery. Considering the whole process, magnetic separation and carbothermal reduction, the recovery of Fe from the zinc mine tailings was 67%. Therefore, the process route suggested in this study will not only reduce tailings disposal and consequently the risk of environmental accidents, but it will also provide profitable raw material for the steel industry.     

无烟煤工业型煤在生活锅炉上的燃烧试验研究

在一台ＳＱ４００－Ｑ型生活锅炉上对无烟煤原煤和工业型煤进行对比燃烧试验,结果表明：燃用工业型煤比燃用原煤热效率提高２１８３％,节煤率为１９４５％,固硫率提高５００５％,烟尘排放浓度降低４７５０％,烟色降至林格曼０５级以下,具有明显的经济效益和环保效益．     

Basic properties of steel plant dust and technological properties of direct reduction

Basic physicochemical properties of the dust from Laiwu Iron and Steel Co. Ltd. were studied. It is found that C, Zn, K, Na, etc. exist in the fabric filter dust, off gas (OG) sludge, fine ash in converter, and electrical field dust in sinter. Among these, OG sludge gives the finest particle, more than 90% of which is less than 2.51 mm. The dust can lead to a serious negative influence on the production of sintering and blast furnaces (BF) if it is recycled in sintering. The briquette and reduction experime...     

Phenolic resin binder for the production of metallurgical quality briquettes from coke breeze: Part II the effect of the type of the basic catalyst used in the resol production on the tensile strength of the formed coke briquettes

In order to develop a new and cost effective formed coke production process which does not require higher temperature carbonization stage, coke breeze was briquetted with resol binders and the change in the tensile strength of the briquettes with the amount and the type of the alkaline metal hydroxides, alkaline earth metal oxides, their carbonates and amine catalysts were studied. It was recognized that carbonates of alkaline or alkaline earth metals have a modifying effect on the properties of resol binders which results in briquettes of higher tensile strength than the resol produced with hydroxide or oxides of these metals. The average tensile strength of the briquettes was found to be much higher with the sodium carbonates catalyzed resol used as binder comparing with sodium hydroxide catalyzed resoles. The former was 45.40 MPa while the latter was 33.72 MPa. Although triethanolamine catalyzed resol, resulted in the briquettes of the highest tensile strength (53.43 MPa), among the catalyst studied in this work, due to flammability caused by triethanolamine, it was found unsuitable for this purpose.     

无黏结剂型煤块配煤炼焦试验研究

利用煤压机压制的无黏结剂型煤块进行炼焦试验,结果表明,随着型煤配量从0到10%、15%、再到20%,焦炭冷热态指标整体呈改善趋势。当型煤配量达到20%时,与型煤配量为0时相比,焦炭的M30改善2.8%、M10改善2.5%,入炉煤多装约3%。在保持焦炭强度不变的基础上,可以通过配用型煤减少价格高的主焦煤配量,达到降低配煤成本的目的。