This paper is a detailed report about the development of a rice destoner. Rice is a major food crop in the world; rice is also an important food crop in Nigeria. Rice is grown in Nigeria but imported rice is preferred to local rice due to the presence of stones in local rice. To solve the problem of destoning local rice a rice destoner was developed.
Destoning is a processing technique for removing stones and impurities from rice. The developed destoner was designed with Autodesk Inventor. The destoner was fabricated with cheaply available materials. The major components of the rice destoner are; the hopper which is the entry point of the rice in the machine, it has a sieve with opening to separate the rice from the stones larger than it and also a second sieve which separates smaller stones from rice. The destoner is powered with a 2.5 horsepower electric motor which is used to incite vibratory motion in the machine.
The developed destoner has an average efficiency of 88.09% and its average working capacity is 12.83 kg/hr. A better performance will be obtained by increasing the number of sieves and adding a vibrating container.
1.1 GENERAL OVERVIEW
Rice (Oryza sativa) is a cereal belonging to the Gramineae, a large monocotyledonous family of some 600 genera and around 10,000 species (Wibberley, 1989). Rice is one of the most important human food crops in the world, directly feeding more people than any other crop. Rice grows under varying climatic conditions, from the wettest areas in the world to the driest deserts. It is produced along Myanmar’s Arakan Coast, where the growing season records an average of more than 5,100 mm of rainfall, and at Al Hasa oasis in Saudi Arabia, where annual rainfall is less than 100 mm (CGIAR, 2018). In the upper Sind in Pakistan, the rice season averages 33 °C; in Otaru, Japan, the mean temperature for the growing season is 17 °C. The crop is produced at sea level on coastal plains and in delta regions throughout Asia, and to a height of 2,600 m on the slopes of Nepal’s mountains (CGIAR, 2018). The two most widely produced species of rice are Oryza sativa and Oryza glaberrima.
The world rice production and land area used in cultivation from 2008-2017 is shown in the figure below. In the year 2013 about 730 million tonnes of rice was produced. Rice production declined in 2014 and 2015 but increased progressively in 2016 and 2017. In 2016 rice production was 751.9 million tonnes (499.2 million tonnes, milled basis), more rice was produced in 2017 (FAO, 2017).
Figure 1: World rice production. Source: FAO
Most of the world’s rice is produced in Asia and includes countries such as China, India, Indonesia, Bangladesh, Vietnam, Thailand and Philippines.
In Africa, rice is majorly produced in the western part of the continent. The major rice producers in West Africa are Nigeria, Mali, Guinea, Sierra Leone, and Cote d’Ivoire. Nigeria is the largest producer of rice in West Africa, Nigeria is the largest importer of rice and also the largest consumer of rice in Africa (FAO, 2017).
1.1 BACKGROUND OF THE STUDY
There is no doubt that petroleum (crude oil) has contributed substantially to Nigeria’s revenue since its discovery in 1956 and more especially, since 1970 when its price was on the upward trend, it is a well-known fact that Nigeria's continuous large earnings or revenue from this sector will be impossible due to the reduction in oil price. Furthermore, it is a known fact across the globe that for a country to attain growth and development, such country’s economy has to be diversified. (Adams, 2016). Moreover, (Attah, 2012) expounds that food security has become an issue of global concern in recent time. Nigeria, with her huge endowed natural and human resources is not spared. Nigerian food crisis is a product of neglect of the peasant agriculture and food crops sub-sector as well as over reliance on the oil sector.As reported by the USDA, importation of rice did not follow a regular pattern but it is observed that rice importation was increasing from 2006 till 2011. The year 2011 gave the highest import with 3.2 million metric tons. After 2011, there have been decreasing rice imports till 2015. By the year 2016 rice imports increased slightly (USDA, 2018). This is shown in the figure below.
Figure 2: Rice importation in Nigeria. Source: USDA
From the above figure it can be calculated that Nigeria has imported 21 million tonnes of rice over the past eight years.
In the year 2016 alone, the demand for rice was 5.2 million tonnes while Nigeria imported 2.5 million tonnes. Nigeria spends $5million a day for rice shipments and rice accounted for 1.26% of the entire budget for 2017 (BBC, 2017).
Rice goes through a series of processes before finally reaching the table. Its production can generally be divided into the following stages: Seed selection, land preparation, crop establishment, water management, Nutrient management, Crop health, Harvesting, and Postharvest. (CGIAR, 2018)
1.1 STATEMENT OF THE PROBLEM
Local rice varieties are sweeter, have better smell and fresher than imported rice but faces competition from imported rice (which is favoured for its clean, stone free grains). Some people claim indigenous rice is hazardous to human health due to the presence of stones particles and pebbles. The preference of imported rice is due to low processing technology of indigenous rice that introduces stone particles and pebbles.
There are available destoners but they are very expensive for local rice farmers to purchase.
Eliminating stones from Nigerian rice, by using a destoner with locally available materials at low cost compared to expensive imported ones, would allow Nigerian locally produced rice varieties to be appreciated better than imported varieties. Improvement of the quality of local rice will discourage rice importation, which will boost production of local rice and consequently improve the economy of the country.
1.3 AIM OF THE PROJECT
The aim of the project is to develop a rice destoner.
1.4 OBJECTIVES OF THE PROJECT
In order to achieve the above aim the objectives carried out are:
a. to investigate traditional ways of removing stone from rice.
b. to adapt the method in (a) to design machine components.
c. to fabricate the machine using results from design calculations.
d. to evaluate the performance of the fabricated machine.
1.5 CONTRIBUTION OF RESEARCH TO KNOWLWDGE
The contribution of research to knowledge are:
1. The development of rice destoner will increase the quality of local rice productivity.
2. The development of rice destoner will increase the demand of local rice.
3. The development of rice destoner will reduce rice import which will increase the Gross domestic product (GDP) of the country.
1.6 SCOPE OF RESEARCH
The research focuses on local rice within Nigeria, most especially the South-Western part of the country.
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